Transfers / desalination – Pen and paper
Miguel Ángel Ródenas Cañada and Juan Guillamón Álvarez
DESCRIPTORS
HYDROLOGICAL WORKS WATER DESALINATION WATER MANAGEMENT ENVIRONMENT MEDITERRANEAN ARCH CALIFORNIA
I are not convinced that a desalination plant
is a viable long-term way to ensure London has an adequate supply, of water"
(Ken Livingstone, Mayor of London)
This article intends to give a grounded analysis comparing two very different ways of approaching the solution for the water problems in the southeastern area of peninsular Spain: on one hand that of the repealed NHP (National Hydrological Plan) (2001), whose most prominent measure is the water transfer from the river Ebro, and the other what is known as the A.G.U.A. Programme (2004), whose main feature is desalination.
The salient feature of the Segura basin is its shortage of available water and a warm and bright climate. Its ancient culture as regards water management can be seen in the extensive development of hydraulic infrastructures and in the best practices of efficiency in its use, both in the general public supply and in irrigation.
The supply to towns and cities is basically run by the Mancomunidad de Canales del Taibilla (Fig. 1). This is a general intercommunity system supplying drinking water to a maximum population of around three million in the Segura and part of the Júcar basin. It involves around 500 kilometres of main canals and a further 1000 kilometres of pipelines. It uses resources from diverse origins: water from the Tajo, water from the Taibilla, underground water and in extraordinary situations, water from the Segura and the Júcar. What is more, recently desalted waters are being used. The diversity of its sources and the extension of its infrastructures means that it provides a good guarantee of supply. It is a good model of rationality and interterritorial cohesion. The official “single” price rate for this supply is high: 0.31 euros/m3.
The Segura basin has around 266,000 hectares of irrigated land, mainly fruit trees and vegetables, which constitute a basic economic activity in the territory and produce positive effects on the Spanish economy. A very large part of the irrigation water comes from the Tajo-Segura transfer (Fig. 2). The corresponding irrigable zones have modern pressurised irrigation infrastructures, in many cases computer-managed, which give effective control over the use of the water. The modernisation of irrigation systems in very many cases goes as far as the application of water to the plant itself, with localised irrigation. An average guideline price for water, at the plot itself, is around 0.14 euros/m3, although there are extreme situations.
The hydrological planning of the Segura basin (1998) has the following objectives (Chart 1): 1) Guaranteeing the present and future urban supply, as a basic premise for the socio-economic and territorial premise. 2) Maintaining the existing irrigated land and thus the economic activity created 3) Regenerating the water environment (recovery of overexploited aquifers, riverbeds and wetlands).
The quantification of the scenario for planning (Chart 2) is materialised in a demand for 2,000 hm3/year (in the hypothesis of integral optimisation of the management measures) with the greatest consumption stemming from irrigation. On the supply side, the internal resources of the basin can at present be evaluated as around 800 hm3/year, including reuse.
Hence the annual water balance of the Segura basin displays an internal deficit in the best optimisation conditions, of 1,200 hm3. This serious imbalance is remedied with the net flows from the Tajo-Segura transfer of 540 hm3, with desalination flows (at present around 40 hm3), and with intensive usage of subterranean waters which goes beyond sustainable use (overexploitation of aquifers).
In these conditions it is impossible to cater for the demands with any guarantee, those for public supply being very tight, and unsustainable for irrigation (lower irrigated surface area than the nominal one, under-endowed irrigated land or with bad quality waters). An extreme environmental situation also stems from this, with overexploitation of aquifers, reduction of environmental flows, loss of quality of waters, salinisation of the soil and an alarming desertification process - in short an undesirable situation, to be solved by the NHP.
The Segura basin has experience in transfers and desalination. Two significant measures are respectively going to be considered for this study: the Tajo-Segura transfer (1979) and the desalination plant of the Alicante Canal of the Taibilla (2004).
The Tajo-Segura Aqueduct (TSA) is an infrastructure with a simple operating scheme: pumping at the starting point (Fig. 3) and a transport canal (Fig. 4) of roughly 300 kilometres as far as the Segura basin. The transport energy of the canal ranges, depending on the section, from 0.1 to 0.4 m/km, there also being several drops for potential energy use. It delivers the waters in the Segura at a coordinate of 650 m snm. The waters are distributed partially using the natural watercourses of the Segura and the post-transfer canals, with which it reaches the Almanzora basin in Almería. The system requires complementary partial elevations in its distribution. The average weighted energy consumption is around 1 kWh/m3.
The users of the TSA assume all the costs: the waters transferred to the South-east have a single rate for irrigation and another for household supply, with a slight discrimination of this as opposed to irrigation, working out with a weighted average price of 0.10 euros, which includes the amortisation of the works (Chart 3). The experience given by 26 years’ operation reveals a technically simple operating system. The nominal maximum flow is 600 hm3/year and the average flow transferred over the last eight years has been 519 hm3, according to the requests of the users and the water available at the head of the Tajo. There is an environmental safeguard to maintain an ecological flow of 6 m3/s in Aranjuez and an economic compensation is given to the Autonomous Communities of the Tajo basin.'
The desalination plant for seawater of the Alicante Canal of the Taibilla has a capacity of 50,000 m3/day (18 hm3/year). It is a modern inverse osmosis desalination plant, equipped with energy recovery with Pelton turbines. The facilities include pumping up to a regulation deposit. Chart 4 shows the main economic data for these facilities. The total power consumption is around 5 kWh/m3, 3.3 kWh/m3 of which correspond to the osmosis process. It gives a desalination cost of 0.70 euros/m3 without a subsidy and 0.60 euros/m3 if the subsidy is considered5 (a figure that is six times higher than that of the water transferred from the Tajo –0.10 €/m3-). The water from the desalination plant pours into the Alicante Canal of the general Taibilla system, to which it contributes 8 % of its total resources as a complementary source of provision.
The White Paper on Water (WPW), qualifies the situation of the Segura basin as one of "structural deficit'; being characterised because in spite of using all its water resources, of making use of all the possible hydraulic works possible and achieving optimum management of water, it is not viable to solve its problems "by itself ", external flows having to be contributed.
The WPW formulates a new approach to the water policy, which is the basis of the NHP. It thus discards the old idea of the regenerationists of considering the supply of water as fostering income, at the same time as recognising that the lack of water should under no circumstances entail a limit to the legitimate development of the different territories of Spain, with no detriment to the conservation policy of the water environment. The WPW considers savings and proper usage measures (which are known as “policies for demand management") as priorities, to be implemented internally in the basins, such as modernisation of irrigation systems, waste water purifiers, reuse, renewal and modernisation of conduits, amongst others. All these measures constitute the fundamental body of the NHP, stated in its articles and very specifically in Appendix II of the NHP.
Furthermore, Appendix II of the NHP included other hydraulic infrastructures to provide new resources in the different basins, such as regulating dams, conduits and desalination, giving priority to carrying out these works in the most problematic basins (Art. 36).
When all the foregoing is not sufficient, the approach of the WPW is to resort where applicable to transfer, which though being an exceptional means to solve a shortage which cannot reasonably be solved any other way, is also a valid instrument for water management: always under the basic premises of not limiting the development, not harming the transferring basin, nor causing unsustainable impacts on the environment.
Hence the NHP looked into the way to deal with the problem of the Segura basin, along with the situation of other basins in the Mediterranean arch which as a whole support an overall water deficit of 1,000 hm3/year. The size of this figure meant that widespread desalination had to be discarded as a general procedure due to its technical, economic and environmental disadvantages. Nevertheless, the viability of solving this deficit by means of a transfer was appreciated, taking into account the availabilities and possibilities of use provided by the flows of Spanish rivers, with contributions of 110,000 hm3/year for a total consumption of 20,000 hm3 (18%), and since correcting the whole deficit of the Mediterranean arch means less than 1 % of peninsular runoff.
The Preliminary Project of the National Hydrological Plan put to the National Water Board (NWB) included a study of the technical, economic and environmental feasibility of possible transfers from some basins to others. It was the NWB itself which, when looking into the different options and combinations of possible transfers, concluded that the ideal option to solve the shortage in the Mediterranean arch was the annual maximum transfer of 1,050 hm3 from the mouth of the Ebro to the internal basins of Catalonia, and wings of the Júcar, Se¬gura and Almería; a feasible transfer from the hydrological standpoints (sufficient water), technical and environmental, and also the most economical of the options.
The Segura basin is allotted 450 hm3. Apart from this transfer, which constitutes its main scheme, and from the other measures for improving management (consolidation of the Tajo Segura and others), the NHP envisages seven desalination plants, completing the guarantee of water supply to the Segura with a maximum estimated flow of about 200 hm3/year (approximately 10 % of the demand). The NHP thus provides a reasonable correction of the water shortage in the Segura basin.
The NHP was definitively approved in 2001 and was integrated in the 2000-2006 budget scenario of the European Union, to benefit from its subsidies. It was also coordinated with other territorial and sectorial measures and basically with the National Irrigation Plan (2002), given the importance of these in the usage of water in Spain (80%).
The NHP was a State project which marked the culmination of a whole integral planning process established in the Water Law of 1985; hard work involving over 20 years of information and studies carried out by the different administrations and subject to public participation and debate as had never been done before by any infrastructure plan in the history of Spain; a strategy whose approaches may meet more or less approval, but which stems from a technical and environmental maturity making it reliable.
The infrastructure of the Ebro transfer provides a guarantee of continuous water supply in the territory, over the 900 kilometres of its route, contributing to the socio-economic development of the territory in the short, medium and long term. It affects a prosperous corridor inhabited by over 10 million inhabitants with a major tourist influx and competitive agriculture. The river Ebro basin has a surface area of 85,000 km2 (18% of Spain), belonging to nine Autonomous Communities. It has resources of roughly 18,000 hm3/year, of which the transfer envisages a drawoff of 6% After deducting the losses in transport (5%), the net use of 1,000 hm3 was envisaged: 439 hm3 (44%) for public supply and 561 hm3 (56%) for consolidation of irrigation systems and water recovery (mainly overexploitation of aquifers).
The drawoff point was located downstream of the Cherta dam, which is the last point where the river is exploited (Fig. 7), going by the criterion of giving priority to the uses of the delivering basin (Chart 6).
A study has been made with the real flows poured into the sea over the last 12 months (Fig. 8) from which the conclusion drawn is that in spite of the present drought 1,050 cubic hectometers could have been transferred.
A project for transfer from the Ebro is conceived to be financed by the users at a single price rate, regardless of the point of supply. This is a model similar to that of water supply (Taibilla, Isabel II Canal), to the electricity, gas or telephony supply, where all the users contribute with the same price to paying for the project and exploiting this. This is a joint endeavour where mutual cooperation, cohesion and solidarity are the main values. This premise comes into the State project category in the most basic sense, which also refers to supplying a natural resource, in the public domain, vital for economic activity and for life itself. Failing to see it as such brings in negative factors to convergence of regional economies, when the most distant ones from the Ebro are also the ones with least wealth.
Under this premise of independent rates in respect of the point of supply, the breakdown of the average price of the waters transferred has been made (Chart 7) according to the conventional method of studying the economic viability of infrastructures.
The investment envisaged is 4,200 million euros, according to the planned route at 1:25.000 scale. The repayment of the works has been done considering the French formula of constant annual quotas, with a reasonable write-off time of 50 years (the Tajo-Segura has been in good use for 25 years.)
The calculation of power consumption is the one obtained from the longitudinal profile of the initial project for the layout, improved with studies of power efficiency made later to define the construction projects with greater accuracy. The total pumping power is around 2,500 GWh and the use made of power (turbining at the trunk and transversal pumping) is around 500 GWh, meaning that the weighted average net consumption is around 2 kWh/m3.
The economic calculation also includes annual compensation dues of 30 million eu¬ros (0.03 €/m3) for the delivering basin.
The final price comes to 0.36 euros/m3, which drops to 0.30 euros/m3 considering the European aid foreseen.
If a calculation of rates with discrimination by uses is established (Chart 8), starting from a maximum assumable price for irrigation of 0.15 euros/m3, this would lead to an urban public supply of 0.49 euros/m3 - a very attractive price for this usage which would still be far under the cost of desalinated water.
One of the greatest benefits of the Ebro transfer stems from its layout in the territory in corridor form. The linear arrangement of the transfer at a high altitude enables creating a “continuous” supply over the whole length of the infrastructure and also at the appropriate coordinate so as not to have to raise this later on; quite a different matter from the desalination alternative, which would require conduits and complementary elevations from the coast to the point of application.
In the Segura basin, the transfer intended to come in at coordinate 500 m snm, running close to irrigable zones (Fig. 9) and at an ideal height; it partially takes advantage of the infrastructure of the Tajo-Segura transfer and is complemented with this; it is also compatible with the main irrigation and public supply conduits. There is a possibility of dealing with the internal distribution of the Seguro using the existing hydrographic network or not, as appropriate, and with the option of providing ecological flows in its basins.
All the irrigable zones which would be supplied in the Segura basin by the Ebro transfer are in a precarious situation through the lack of a guaranteed supply, since these are supplied by overexploited aquifers. Replacing flows of waters from overexploited sources by transferred waters would enable this undesirable practice to be discarded, with the benefit meant by the natural recovery of the phreatic levels, in a slow process of natural replenishment. The final result would be the re-emergence of springs and sources and the corresponding regeneration of watercourses, brooks and rivers. The Ebro transfer thus constitutes a genuine project of environmental regeneration for the Segura basin, as put forward by the Water Framework Directive.
This possibility of environmental regeneration of the water environment of the Mediterranean coastline provided by the transfer is particularly stressed by the Berkeley report.° Said report, which gives an in-depth analysis of the hydrology and water resources of the river Ebro minimises the significances of the effects that transfer’s drawoff flows may have on the Delta precisely through their low quantity in relation to the flows of the river. What is more, this report stresses that the transfer project, with its corrective and compensation measures, is a good chance to improve the situation of the Delta (Fig. 10).
The linear layout and continuity of the transfer forming a corridor 900 kilometres long will allow the location of long-distance infrastructures, complementary or not, of power, communications and others, which may be of great strategic interest, with an environmental impact already recouped.
The route planned takes advantage to a great extent of hydraulic infrastructures already existing, minimising its impact. The effects on the Natura 2000 network are the very minimum (three crossovers of rivers and a marginal anthropised area). The project for the Ebro transfer was submitted for public information and Environmental Impact Assessment, obtaining the compulsory favourable Declaration.
The Ebro transfer is a strategic element for the supply and distribution of water in Spain and this has repeatedly been considered as such in all the strictest hydraulic studies and plans made over history. In all these earlier plans, the proposals for flows to be drawn off from the Ebro were higher than the ones considered in the NHP-2001. We could stress, amongst others, that of Félix de los Ríos (1937) and that of the Hydrographic Study Centre10 (1967). More recently it was also considered a key part of the Preliminary Project " of the NHP-1993. The project for the Ebro transfer also meets Community regulations 12 and in particular the Structural Water Framework; s whose compliance is precisely one of its aims.
The NHP discarded the widespread desalination of seawater as an instrument for providing large volumes. Certain considerations in this respect have already been put forward. Others will now be given.
The only advantage offered by desalination is that the raw material is inexhaustible and is not subject to rainfall. What some politicians consider as a great advantage of desalination, its "independence'; is not actually so, since values and practice of cooperation and solidarity are necessary in a nation
The desalination of seawater through inverse osmosis, which is the one at present being considered in Spain, is complex and requires a lot of technology. The membranes are covered by patents and depend on external technology. There have been great disappointments with desalination even in technologically advanced countries. Many examples have been seen in which the fast clogging of the inverse osmosis membranes has made the planned operating costs soar to extreme limits, as occurred with the desalination plant in Tampa'^ in Florida (United States). On the Andalusian coast there have also been major problems and a bad track record through technical, economic or management difficulties in large seawater desalination plants, as is the case of those of Costa del Sol, Carboneras, Almería and others." Consequently, the secure water supply that is in theory provided by desalination, may actually not be such if one considers the greater likelihood of failure, technical or management shortcomings, as is shown by experience.
The high power consumption of desalination, 2.5 times greater than transfer (to which one must add, where applicable, that of the relevant pumping operations) may lead to an uncertain economic situation, in the present scenario of absolutely unforeseeable, though always rising, power prices. Large-scale desalination is prejudicial for national power policy, as it contributes to the imbalance of our balance of payments, and also has a negative effect on environmental policies, making it difficult to comply with the Kyoto protocol.
The waters from desalination are chemically unbalanced, with high acidity and presence of some harmful elements, such as boron, both for the supply of towns and for crops, especially citrus fruit'° They need to be mixed with other water or more complex and costly treatments. In towns such as Las Palmas, with a high percentage of desalinated waters, the people do not drink tap water through its unpleasant taste.
The brine rejected from desalination constitutes a contaminating element through its salt concentration and its content in chemicals from prior treatment. Its pouring into the sea in large quantities as waste from large desalination plants requires a special study on impact for the environment. The increase in salinity from seawater as a result of dumping brine decisively affects some highly valuable species of the Mediterranean sea, such as the posidonia oceanica" (Fig. 1 1), very common on our coasts (Fig. 12).
The location of large-scale desalination facilities close to the coast also involves two major disadvantages. On one hand, the difficulty of locating large regulation dams as required by irrigation, if this were to be with desalinated water, and on the other, the actual territorial environmental impact of locating the plant on land with higher value such as the coast, an impact which would be considerably heightened with the need for high voltage electricity lines and transformation substations for high power.
Although it is very difficult to establish a comparative process between transfer and desalination, chart 9 shows a summary of different aspects treated.
In spite of what is stated above, major progress has doubtlessly been made in desalination technology, though still not enough for the annual provision of 1 km3 of water. In this respect the NHP considered that desalination is necessary and can solve some specific and particular problems for reinforcing supply, with a transitory nature, for periods of drought and in general to help to give a more complete guarantee, but always as a complement. Appendix II of the NHP thus included the relevant figure of 38 desalination facilities in the Mediterranean area, the islands and Melilla.
California has characteristics very similar to Spain in some aspects as regards the geography, climate, availability and uses of water (Chart 10).
In California, as in Spain, there is an imbalance between the supply and demand for resources (Fig. 13). There, these are corrected with water transfers: transfers supply 18,800 hm3/year, which represents 32 % of the total supply. Figu¬re 14 represents the main transfer plans in California, which are used both for supplying the public and for agriculture.
Desalination in California, which has a supply capacity of 13 hm3/year (representing 0.01 % of the total supplies), is done by means of 12 plants, located mainly in the south, mostly operating sporadically or inactive. Today other desalination plants are proposed in California to serve mainly coastal communities. If all the plants proposed were finally built the total supply would be about 320 hm3. That is, about 0.3 % of the total.
The case of the city of Santa Barbara is highly significant: this was traditionally supplied by surface waters, subsurface waters and reuse. From 1986 to 1991 they underwent a serious drought, which led them to build a desalination plant as a temporary emergency source and a transfer of water from the north.'9 The desalination plant was completed in 1992 and since that time (the end of the drought period) it has been on standby status. The transfer was completed in 1997 and has been running ever since. The water costs are given in chart 11.
In 2005 in California, Stokes and Horvath20 drew up a comparative study between transfers and desalination with an analysis of the integral life cycle. Charts 12 and 13 respectively give the results referring to water consumption and the emissions of greenhouse effect gases and other atmospheric contaminants. Charge 14 also shows the comparative operating costs with further data from other sources.
California’s experience comes down to the following: 1) water transfers represent the main source of water supply, 2) desalination acts as a complementary and back-up source, and 3) water transfers involve lower power consumption, lower emissions and lower associated costs than desalination.
After the execution of the NHP had started (February 2004), the new Spanish government decreed a substantial modification of this (RDL 2/2004), repealing the Ebro transfer. This was known as the A.G.U.A. programme. This extremely rushed (plan-reversing) measure was carried out without any alternative hydrological plan and with no further documentation than the five sheets of the State Gazette taken up by the relevant Decree Law, apart from two short reports, in a process utterly out of proportion with the scale of the previous planning and thus casting doubt on the technical thoroughness and correctness of what it puts forward.
To fill in the vast gap entailed by this step and justify the repeal of the Ebro transfer, the A.G.U.A. programme starts by invoking a "new water culture" (actually merely obvious principles of good management of demand and protection of the environment already envisaged in the NHP, which are now made radical with a visceral rejection of hydraulic works). Secondly, it puts all the emphasis on desalination of seawater as main source of water resource supply; that is, the main aspect of the NHP (the Ebro transfer) is scrapped, and what was only a complement in this (desalination) is now given the nature of single and main solution.
As regards the River Segura basin, the A.G.U.A. programme envisages a list (Appendix IV of priority and urgent measures) with 32 measures, which is the result of selecting 22 of the 71 measures included in the former Appendix II of the NHP, to which 10 new ones are now added (Appendix III). Two new desalination plants and action known literally as "urgent measures for supplying resources to the Al¬tiplano and Alto Guadalentín", which have not to date been defined, are worthy of mention, in the part newly added.
It should be stressed that this A.G.U.A. programme approved in Parliament has not been officially submitted for any strategic environmental assessment,2 quite contrary to its apparent environment-friendly basis. In April 2005 a report on Environmental Sustainability was presented attempting to justify the environmental correctness of the decisions made in 2004 a posteriori and officially getting the aforementioned assessment under way.
Barely one year later a second modification of the NHP has already gone through Parliament (Act 1 1 /2005), which is basically the previous Decree-Law with small alterations and a partial reform of the Water Law. In the Segura basin, this second modification introduces a new item of concern in addition to the repeal of the Ebro transfer, a reduction of the Tajo-Segura" transfer; it also adds five new measures in Appendix IV, but without any significant repercussion as regards new resources.
Figure 15 shows a comparative view of the external water resources planned in the National Hydrological Plan and the A.G.U.A. programme, which also reflects the unitary average prices for the different sources, according to what is justified herein. The conclusion drawn from this is that the forecasts for water supply in the Segura basin are considerably lower and the costs of water clearly higher by reducing precisely the cheapest sources.
With the A.G.U.A. programme the shortfall comes to about 600 hm3/year, that is 30% of the demands of the Segura: an unsustainable situation leading to undesirable confusion in water matters, progressive deterioration of the environment and a loss in guarantees endangering about 40% of the irrigable surface area, about 100,000 hectares of irrigated land.
It only provides solutions for the supply of Taibilla, thanks to its nature as a general system, though it introduces an increase in water prices with a drop in competitiveness and unfavourable socio-economic effects for regional development. As for irrigated land, the high prices of desalination only make it viable as a complementary resource (mixed waters) and also in locations close to the coast. The recovery of overexploited aquifers and other environmental regeneration measures are non-viable with desalination waters.
Chart 15 shows all the considerations in this study and reveals that the A.G.U.A. programme is insufficient and only represents a partial solution for the Segura basin.
Apart from constituting a partial solution and increasing the price of water, its application is highly likely to be delayed (the Ebro transfer was planned to come into operation in 2008). The new measures whose planning is now being attempted require definition times and technical design and administrative periods for authorisations, expropriations and public tenders which entail a delay in providing results and involve the danger of forfeiting European financing.
The Ebro transfer constitutes a key measure for hydrological planning in Spain. It is the ideal infrastructure in the short, medium and long term for catering for the large demands of water spread linearly down the Mediterranean arch. This is a technically and economically feasible project and also (an important matter) compatible with the environment. This is a project able to be extended in the future with new sources, such as water banks, the water of the Rhone25 or others. Its repeal was the greatest error in hydraulic policy in the history of Spain. The execution of this project should recommence as soon as possible.
Highly prosperous countries which have arid zones and sufficient water in other parts such as California solve their water shortages with general large capacity water supply systems, founded on conventional hydraulic works, such as dams, conduits and transfers, handled according to widely accepted criteria on which sustainable development is sustained.
Plans based on widespread desalination do not constitute an alternative to the general system of transfers due to their high economic and environmental cost. A relevant decision in this respect was recently (1995) made in London, a city in which there has been a marked change of plan ruling out large-scale desalination. Desalination may however play a complementary role in hydrological planning, if implemented in moderation and in uses for which the prices of water does not mean a decisive factor.
With a little use of pen and paper, the concepts mentioned can doubtlessly be explained quite clearly, not only from the technical and environmental standpoint, but also with pure and simple common sense, which is, with certain exceptions, within everyone’s reach.
Miguel Ángel Ródenas Cañada and Juan Guillamón Álvarez
Civil Engineers
Notes
1. Water available from the Segura. The water available from the Segura basin is under 1,000 m3/inhab/year. This marks the threshold of a “catastrophic” situation according to the report The development of water resources in the world. Water for people. Water for life, UN, Kyoto, March 2003.
2 Trade balance. The production of fruit and vegetables in the Mediterranean arch is a positive item in Spain’s trade balance. Only the Region of Murcia, with 3% of Spain’s population, represents 20% of Spain’s exports, with two million tons and 1,313 million euros (Source: FE¬12004). This is a competitive business, which does not depend on CAP subsidies, and is commercially sustainable. The main threat to it is the lack of water.
3. Limitation of extension of irrigable zones. The Segura Basin Plan considers it vital to maintain the economic and commercial structure created by the irrigated land existing at present: highly competitive irrigated farmland, necessary for EU food supply and with a territorial and environmental impact that has already been recouped. In a scenario with a serious water shortage, this premise has more guarantees of being attained with an absolute limitation of irrigable areas: the Segura Basin Plan thus imposed this very strict condition. The possibilities of fostering this activity are thus restricted to greater productivity without increasing the irrigated surface areas.
4. Economic transfers from the Tajo-Segura. One singularity of the economic-financial system of the Tajo-Segura is that the quotas received for amortization of the work are used for carrying out hydraulic works in the Autonomous Communities of the delivering basin, as compensation. From 1979 to 2004 188 million euros have been transferred for this item.
5. Financing of hydraulic works. As a general rule, for the 2000-2006 period, hydraulic works in Spain qualify for aid from the EU: Cohesion Funds in the whole national territory and ERDF funds depending on categories of regional income. For the 2007-2013 period the situation changes for Spain due to the extension of the EU. It loses the right to Cohesion Funds and aid is also drastically reduced in the Murcia and Valencia regions, which are disqualified as Objective 1 areas through exceeding 75% of the GDP/pc. To enable a uniform comparative study, this article has used the aid figures expected by the Ministry of the Environment in 2003 for the main infrastructure of the NHP, the Ebro transfer (1/3 of the investment).
6. “Libro Blanco del Agua in Spain” published by the Ministry of the Environment (1998). This is possibly the best compilation in the world on the situation of a State’s water resources. This is a real “hydraulic” photo of Spain with a "pixel" of 1 Km. x 1 km. It was drawn up from the huge amount of information prepared for the hydrological plans for the basins and updated with specific information. With widespread dissemination, it acted as a document for analysis and debate to formulate the bases of the NHP.
7. Economic optimisation of transfers. In the preliminary project of the NHP combinations of possible transfers are analysed. The optimum flow from an economic standpoint is the option chosen of the Ebro transfer, with values around 0.30 €/m', as opposed to values over 0.40 euros/m represented by other possible combinations of Ebro+Duero+Tajo.
8. Spanish Constitution. Article 45.2: "Public authorities will safeguard the rational use of all natural resources, in order to protect and improve the quality of life and defend and restore the environment, supported by essential group solidarity ".
9. Berkeley Report. A Technical Review of the Spanish National Hydrological Plan (Ebro River Out-Of-Basin Diversion) (January 2003). An independent report on the NHP and the Ebro transfer, commissioned at the request of the European Union Commission. The editing committee was selected by the EU Research Centre of the EU in Ispra (Italy). The authors are: Alexander J. Horne, John Dracup and Michael Ha¬nemann (University of California, Berkeley) l Ignacio Rodríguez-Iturbe, Princeton University 1 Edward Means, McGuire Environmental Consultants Inc., Santa Moni¬ca, California 1 James C. Roth, Private Consultant, San Francisco.
This report is a vital reference for proper knowledge of the Ebro transfer project, analysing with a thorough and wide-ranging multidisciplinary view (engineering, hydrology, ecology and economy). Its conclusion is the viability, appropriateness and usefulness of the project for solving problems of water supply and environmental problems in the Mediterranean arch. There is no substantial criticism of the project, though it does establish recommendations and measures to be performed in its implementation and method improvements on details.
10. Background to the Ebro transfer. In 1937 Félix de los Ríos, Director of the Ebro Confederation drew up a plan (with great vision and sense of the general interest) covering the transfer of 1,260 hm year of water from the Ebro for improving and extending irrigated land from Tarragona to the river Almanzora. Similarly, in 1967, the Centre for Hydrographic Studies considered the transfer of 2,800 hm3/year of water from the Ebro to the Mediterranean arch as part of a master plan for correction of the national hydraulic unbalance included in the General Preliminary Project for the Joint Exploitation of the Hydraulic Resources of the Centre and Southeast of Spain -ATS.
11. Preliminary Project NHP-1993 (Borrell Plan). What was also known as the Integrated System for National Hydraulic Balance (SIEHNA) obtained a favourable report from the National Water Board (July 1994). The synthesis of the report then sustained that "large-scale transfers (…) are vital, regardless of what the future evolution of the demands may be". This was an approach on a much larger scale than the PHN¬2001 and a real development plan (600,000 hectares of new irrigated land) rather than a sustainability project like the PHN-2001. This spread out greater pressure over the Peninsula’s water resources, mobilising two large systems, North-Duero-Tajo and Ebro. It also covered over a dozen water transfers: the overall maximum volume of the transfers envisaged was 3,353 hm' and the maximum amount to be reduced from the Ebro basin was 1,642 hm.
12. Transfer and European Union. The rumour that the EU Commission had rejected the Ebro transfer has been spread: this is false; the competence for approving the Ebro transfer rests only with the Spanish State, although the project must obviously adapt to European legislation, a question on which the EU did not make any official declaration. In December 2003 the Spanish government asked the Commission for Community financial aid for building the transfer. The Commission did not make an official statement on this matter either, since while the application was still being analysed the transfer was repealed and the relevant financing application withdrawn (2004).
13. Transfer and Water Framework Directive. It has been said that the WFD prohibited transfers. This is a falsity which furthermore reveals the absolute ignorance of its content and aims, which are quite simply the protection and recovery of the water environment. In the WFD it only mentions transfers once and not even in its articles, but in Appendix ti, section 1.4 Identification of pressures, where it states that the Member states must identify significant anthropogenic pressures, including transfers, in a long list. This is obvious and does not involve any pronouncement nor position of the Directive in favour or against these. Transfers, water supplies, irrigation systems, dams, canals, desalinisation plants and so many measures that it would be impossible to list would be on the same plane as transfers or diversions.
14. Tampa Bay Desalinisation plant. A facility promoted by Tampa Bay Water (public water agency of Florida State) to supply 10% of the water for supply in the region, which is at present supplied by surface and subterranean waters. This is the largest capacity inverse osmosis seawater desalinisation plant in the USA, with a volume of 40 hm3/ year and an investment of 110 million dollars. Its building was started in August 2001 and it has not actually started running due to serious problems in its operation. Recently (2004) a competitive tender was issued for its full alteration. (Source: "St. Petersburg Times", 2nd August 2003).
15. Large seawater desalinisation plants in Andalusia. The desalination of seawater on the Andalusia coast has involved a lot of absurd situations and failures. 1) The Marbella desalinisation plant, with a capacity for 20 hm3/year, was built in 1997 and has not yet supplied even a single hm3 as of June 2005; it is intended to go into operation in July 2005. 2) The Carboneras desalination plant, the largest desalinisation plant for seawater in Europe, with 42 hm3/year, was completed in 2002 and has only worked at 8% of its capacity. 3) The Almería desalination plant, with a capacity for 18 hm3/year, has been inactive until now although its building started in 1999; its partial start-up would seem to be planned for late 2005.
16. Chemical unbalance. The waters released by inverse osmosis, though having low conductivity, have great chemical imbalance as regards natural waters. The high boron content in desalted water is important (values over 1 mg/I), since today’s membranes still have great permeability to this element. Directive 98/83/CE (transposed by RD 140/2003) on quality criteria of water for human consumption does not allow such levels of over 1 mg/l. In farming, the main Mediterranean crop, citrus fruit, and in particular lemons, do not tolerate values over 0.5 mg/l. One should also stress the high acidity and ensuing corrosion caused by pure desalted waters: there are also other undesirable chemical unbalances for crops, such as the high sodium/calcium ratio and others.
17. Salinity Mediterranean waters have a salinity of 37.5 g/l. The brine product rejected concentrates approximately twice the salt content. The great increase in salinity causes the dehydration of the cells of the marine micro-organisms affected. Recent studies made jointly by several Spanish bodies cast doubts on the consequences that large-scale desalination would have for the seabed. These studies show that from 38.4 g/l the meadows of Posidonia oceanica would be affected, i.e., they do not tolerate variations in salinity entailing an increase over 1 g/l. The problem takes on greater relevance through the large size of the desalination plants envisaged, in which the dumping implies a volume similar to that of the water product. The meadows of posidonia form the most important ecosystem in the Mediterranean, the home of 400 plant species and over 1,000 animal species. There are 10,000 hectares of these underwater forests only in the seawater of Murcia region.
18. John A. Dracup. The experiments mentioned from California were drawn from the conference entitled "Comparison of the project for transfers from the Ebro and the A.G.U.A. Programme in the light of the experience in California", held on 5th May 2005 in Alicante and 7th May 2005 at the Royal Economic Society of Friends of Murcia, given by John A. Dracup, professor in Civil and Environmental Engineering of California University, Berkeley.
19. Santa Barbara. A city with 1.5 million inhabitants located to the northwest of Los Angeles. The water transfer supplies 48 hm3 for the county area and 3.7 hm' for the city. The desalination plant has a capacity of 3.7 hm3 and in 2000 it was the largest inverse osmosis desalination plant in the USA.
20. Stokes and Horvath, 2005. Authors of the thesis "Life-cycle Energy Assessment of Alternative Water Supply Systems". Accepted for publication in the "International Journal of LCA". The study was written on two counties in California which have desalination, transferred waters and reuse as sources of water.
21, Hydrological planning. Hydrological planning has characteristics that are highly different to other infrastructure plans. In Spain the 1985 Water Law established a full participative process, prepared from top to bottom, with the Basin Hydrological Plans by the Basin Water Boards, and the National Hydrological Plan, in which the National Water Board also played a fundamental role of coordination and participation in sectorial territorial policies, before its respective approval by the Government or Parliament. Due to its very nature, hydrological planning cannot be improvised nor even less replaced by simple legislative action. Hydrological planning constitutes the rational method to ensure general interest in the field of water. As regards the planning dictated by the Government, there may be doubts as regards how correct its aims are.
22. Environmental impact. From 21st July 2004 Directive 2001/42/CE on the assessment of the effects of certain plans and schemes on the environment must compulsorily be applied. This Directive requires environmental assessment and taking into account authorities’ and citizens’ opinions prior to approval or presentation for legislative procedure of the plan or scheme. The plans or schemes for management of water resources are subject to this rule. At present this Directive has not been transposed to the Spanish State.
23. Modification of the Tajo-Segura. The following text is inserted in the second modification of the NHP (Act 11/2005, additional provision one): "the volume transferable from the head of the Tajo will be reviewed in the future, after hearing the Autonomous Communities affected, as the government makes the investments required to meet the needs of the Segura basin.”
24. Transfer and Water Banks. Experience has shown that the instruments of the Water Law on assignment of rights to use of water and centres for exchange of water usage rights (the so-called public water banks) are useless in the internal domain of a basin with a deficit such as that of the Segura. To make these feasible there have to be connection infrastructures between basins which allow access to major “deposits” of water which may be assigned with the agreed economic consideration. The infrastructure of the Ebro transfer is the only way to make this highly interesting instrument for water management feasible, as the Ebro basin is the greatest potential "depositor' in Spain (5,500 hm3/ year total consumption, with 800,000 hectares of irrigated land which may obtain important savings through their modernisation) and the Mediterranean arch is the main demander. In practice, the repeal of the Ebro transfer strips the policy of water banks in Spain of any content.
25. Other transfers. The NHP -2001 envisaged making studies for incorporating other transfers already mentioned in the preliminary plan itself in the Spanish hydrological system to obtain new water resources in the longer term (additional provision nine of the NHP). The existence of the Ebro transfer infrastructure gives enormous encouragement to this possibility. Hence, one highly interesting example is the Rhone (a fluvial system tripling that of the river Ebro) transfer to Catalonia, where the existence of the Ebro transfer will enable increasing the guarantee or even catering for future additional demands in the southern Mediterranean arch (Valencia, Murcia and Andalusia). The repeal of the Ebro transfer ruins this possibility.
26. London desalination plants. Facilities planned in May 2004 to complement the supply for London. It was going to be the first inverse osmosis plant in the United Kingdom and would collect salt water taken at low tide in the Thames estuary. Capacity: 50 hm3/year (150,000 m3/day); budget: 326 million euros. In April 2005, the project was dropped through an excessive consumption of power, due to its cost and its impact on marine habitats. Ken Livingstone, mayor of London, declared: "l am not convinced that a desalination plant is a viable long-term way to ensure London has an adequate supply of water". It is intended to build a new dam on the upstream Thames, close to Oxford, to store the river’s winter flows; a large-scale plan for pipeline replacement has been arranged to reduce losses. (Source: www.news.bbc.co.uk).
Miguel Ángel Ródenas Cañada and Juan Guillamón Álvarez
DESCRIPTORS
HYDROLOGICAL WORKS WATER DESALINATION WATER MANAGEMENT ENVIRONMENT MEDITERRANEAN ARCH CALIFORNIA
I are not convinced that a desalination plant
is a viable long-term way to ensure London has an adequate supply, of water"
(Ken Livingstone, Mayor of London)
This article intends to give a grounded analysis comparing two very different ways of approaching the solution for the water problems in the southeastern area of peninsular Spain: on one hand that of the repealed NHP (National Hydrological Plan) (2001), whose most prominent measure is the water transfer from the river Ebro, and the other what is known as the A.G.U.A. Programme (2004), whose main feature is desalination.
The salient feature of the Segura basin is its shortage of available water and a warm and bright climate. Its ancient culture as regards water management can be seen in the extensive development of hydraulic infrastructures and in the best practices of efficiency in its use, both in the general public supply and in irrigation.
The supply to towns and cities is basically run by the Mancomunidad de Canales del Taibilla (Fig. 1). This is a general intercommunity system supplying drinking water to a maximum population of around three million in the Segura and part of the Júcar basin. It involves around 500 kilometres of main canals and a further 1000 kilometres of pipelines. It uses resources from diverse origins: water from the Tajo, water from the Taibilla, underground water and in extraordinary situations, water from the Segura and the Júcar. What is more, recently desalted waters are being used. The diversity of its sources and the extension of its infrastructures means that it provides a good guarantee of supply. It is a good model of rationality and interterritorial cohesion. The official “single” price rate for this supply is high: 0.31 euros/m3.
The Segura basin has around 266,000 hectares of irrigated land, mainly fruit trees and vegetables, which constitute a basic economic activity in the territory and produce positive effects on the Spanish economy. A very large part of the irrigation water comes from the Tajo-Segura transfer (Fig. 2). The corresponding irrigable zones have modern pressurised irrigation infrastructures, in many cases computer-managed, which give effective control over the use of the water. The modernisation of irrigation systems in very many cases goes as far as the application of water to the plant itself, with localised irrigation. An average guideline price for water, at the plot itself, is around 0.14 euros/m3, although there are extreme situations.
The hydrological planning of the Segura basin (1998) has the following objectives (Chart 1): 1) Guaranteeing the present and future urban supply, as a basic premise for the socio-economic and territorial premise. 2) Maintaining the existing irrigated land and thus the economic activity created 3) Regenerating the water environment (recovery of overexploited aquifers, riverbeds and wetlands).
The quantification of the scenario for planning (Chart 2) is materialised in a demand for 2,000 hm3/year (in the hypothesis of integral optimisation of the management measures) with the greatest consumption stemming from irrigation. On the supply side, the internal resources of the basin can at present be evaluated as around 800 hm3/year, including reuse.
Hence the annual water balance of the Segura basin displays an internal deficit in the best optimisation conditions, of 1,200 hm3. This serious imbalance is remedied with the net flows from the Tajo-Segura transfer of 540 hm3, with desalination flows (at present around 40 hm3), and with intensive usage of subterranean waters which goes beyond sustainable use (overexploitation of aquifers).
In these conditions it is impossible to cater for the demands with any guarantee, those for public supply being very tight, and unsustainable for irrigation (lower irrigated surface area than the nominal one, under-endowed irrigated land or with bad quality waters). An extreme environmental situation also stems from this, with overexploitation of aquifers, reduction of environmental flows, loss of quality of waters, salinisation of the soil and an alarming desertification process - in short an undesirable situation, to be solved by the NHP.
The Segura basin has experience in transfers and desalination. Two significant measures are respectively going to be considered for this study: the Tajo-Segura transfer (1979) and the desalination plant of the Alicante Canal of the Taibilla (2004).
The Tajo-Segura Aqueduct (TSA) is an infrastructure with a simple operating scheme: pumping at the starting point (Fig. 3) and a transport canal (Fig. 4) of roughly 300 kilometres as far as the Segura basin. The transport energy of the canal ranges, depending on the section, from 0.1 to 0.4 m/km, there also being several drops for potential energy use. It delivers the waters in the Segura at a coordinate of 650 m snm. The waters are distributed partially using the natural watercourses of the Segura and the post-transfer canals, with which it reaches the Almanzora basin in Almería. The system requires complementary partial elevations in its distribution. The average weighted energy consumption is around 1 kWh/m3.
The users of the TSA assume all the costs: the waters transferred to the South-east have a single rate for irrigation and another for household supply, with a slight discrimination of this as opposed to irrigation, working out with a weighted average price of 0.10 euros, which includes the amortisation of the works (Chart 3). The experience given by 26 years’ operation reveals a technically simple operating system. The nominal maximum flow is 600 hm3/year and the average flow transferred over the last eight years has been 519 hm3, according to the requests of the users and the water available at the head of the Tajo. There is an environmental safeguard to maintain an ecological flow of 6 m3/s in Aranjuez and an economic compensation is given to the Autonomous Communities of the Tajo basin.'
The desalination plant for seawater of the Alicante Canal of the Taibilla has a capacity of 50,000 m3/day (18 hm3/year). It is a modern inverse osmosis desalination plant, equipped with energy recovery with Pelton turbines. The facilities include pumping up to a regulation deposit. Chart 4 shows the main economic data for these facilities. The total power consumption is around 5 kWh/m3, 3.3 kWh/m3 of which correspond to the osmosis process. It gives a desalination cost of 0.70 euros/m3 without a subsidy and 0.60 euros/m3 if the subsidy is considered5 (a figure that is six times higher than that of the water transferred from the Tajo –0.10 €/m3-). The water from the desalination plant pours into the Alicante Canal of the general Taibilla system, to which it contributes 8 % of its total resources as a complementary source of provision.
The White Paper on Water (WPW), qualifies the situation of the Segura basin as one of "structural deficit'; being characterised because in spite of using all its water resources, of making use of all the possible hydraulic works possible and achieving optimum management of water, it is not viable to solve its problems "by itself ", external flows having to be contributed.
The WPW formulates a new approach to the water policy, which is the basis of the NHP. It thus discards the old idea of the regenerationists of considering the supply of water as fostering income, at the same time as recognising that the lack of water should under no circumstances entail a limit to the legitimate development of the different territories of Spain, with no detriment to the conservation policy of the water environment. The WPW considers savings and proper usage measures (which are known as “policies for demand management") as priorities, to be implemented internally in the basins, such as modernisation of irrigation systems, waste water purifiers, reuse, renewal and modernisation of conduits, amongst others. All these measures constitute the fundamental body of the NHP, stated in its articles and very specifically in Appendix II of the NHP.
Furthermore, Appendix II of the NHP included other hydraulic infrastructures to provide new resources in the different basins, such as regulating dams, conduits and desalination, giving priority to carrying out these works in the most problematic basins (Art. 36).
When all the foregoing is not sufficient, the approach of the WPW is to resort where applicable to transfer, which though being an exceptional means to solve a shortage which cannot reasonably be solved any other way, is also a valid instrument for water management: always under the basic premises of not limiting the development, not harming the transferring basin, nor causing unsustainable impacts on the environment.
Hence the NHP looked into the way to deal with the problem of the Segura basin, along with the situation of other basins in the Mediterranean arch which as a whole support an overall water deficit of 1,000 hm3/year. The size of this figure meant that widespread desalination had to be discarded as a general procedure due to its technical, economic and environmental disadvantages. Nevertheless, the viability of solving this deficit by means of a transfer was appreciated, taking into account the availabilities and possibilities of use provided by the flows of Spanish rivers, with contributions of 110,000 hm3/year for a total consumption of 20,000 hm3 (18%), and since correcting the whole deficit of the Mediterranean arch means less than 1 % of peninsular runoff.
The Preliminary Project of the National Hydrological Plan put to the National Water Board (NWB) included a study of the technical, economic and environmental feasibility of possible transfers from some basins to others. It was the NWB itself which, when looking into the different options and combinations of possible transfers, concluded that the ideal option to solve the shortage in the Mediterranean arch was the annual maximum transfer of 1,050 hm3 from the mouth of the Ebro to the internal basins of Catalonia, and wings of the Júcar, Se¬gura and Almería; a feasible transfer from the hydrological standpoints (sufficient water), technical and environmental, and also the most economical of the options.
The Segura basin is allotted 450 hm3. Apart from this transfer, which constitutes its main scheme, and from the other measures for improving management (consolidation of the Tajo Segura and others), the NHP envisages seven desalination plants, completing the guarantee of water supply to the Segura with a maximum estimated flow of about 200 hm3/year (approximately 10 % of the demand). The NHP thus provides a reasonable correction of the water shortage in the Segura basin.
The NHP was definitively approved in 2001 and was integrated in the 2000-2006 budget scenario of the European Union, to benefit from its subsidies. It was also coordinated with other territorial and sectorial measures and basically with the National Irrigation Plan (2002), given the importance of these in the usage of water in Spain (80%).
The NHP was a State project which marked the culmination of a whole integral planning process established in the Water Law of 1985; hard work involving over 20 years of information and studies carried out by the different administrations and subject to public participation and debate as had never been done before by any infrastructure plan in the history of Spain; a strategy whose approaches may meet more or less approval, but which stems from a technical and environmental maturity making it reliable.
The infrastructure of the Ebro transfer provides a guarantee of continuous water supply in the territory, over the 900 kilometres of its route, contributing to the socio-economic development of the territory in the short, medium and long term. It affects a prosperous corridor inhabited by over 10 million inhabitants with a major tourist influx and competitive agriculture. The river Ebro basin has a surface area of 85,000 km2 (18% of Spain), belonging to nine Autonomous Communities. It has resources of roughly 18,000 hm3/year, of which the transfer envisages a drawoff of 6% After deducting the losses in transport (5%), the net use of 1,000 hm3 was envisaged: 439 hm3 (44%) for public supply and 561 hm3 (56%) for consolidation of irrigation systems and water recovery (mainly overexploitation of aquifers).
The drawoff point was located downstream of the Cherta dam, which is the last point where the river is exploited (Fig. 7), going by the criterion of giving priority to the uses of the delivering basin (Chart 6).
A study has been made with the real flows poured into the sea over the last 12 months (Fig. 8) from which the conclusion drawn is that in spite of the present drought 1,050 cubic hectometers could have been transferred.
A project for transfer from the Ebro is conceived to be financed by the users at a single price rate, regardless of the point of supply. This is a model similar to that of water supply (Taibilla, Isabel II Canal), to the electricity, gas or telephony supply, where all the users contribute with the same price to paying for the project and exploiting this. This is a joint endeavour where mutual cooperation, cohesion and solidarity are the main values. This premise comes into the State project category in the most basic sense, which also refers to supplying a natural resource, in the public domain, vital for economic activity and for life itself. Failing to see it as such brings in negative factors to convergence of regional economies, when the most distant ones from the Ebro are also the ones with least wealth.
Under this premise of independent rates in respect of the point of supply, the breakdown of the average price of the waters transferred has been made (Chart 7) according to the conventional method of studying the economic viability of infrastructures.
The investment envisaged is 4,200 million euros, according to the planned route at 1:25.000 scale. The repayment of the works has been done considering the French formula of constant annual quotas, with a reasonable write-off time of 50 years (the Tajo-Segura has been in good use for 25 years.)
The calculation of power consumption is the one obtained from the longitudinal profile of the initial project for the layout, improved with studies of power efficiency made later to define the construction projects with greater accuracy. The total pumping power is around 2,500 GWh and the use made of power (turbining at the trunk and transversal pumping) is around 500 GWh, meaning that the weighted average net consumption is around 2 kWh/m3.
The economic calculation also includes annual compensation dues of 30 million eu¬ros (0.03 €/m3) for the delivering basin.
The final price comes to 0.36 euros/m3, which drops to 0.30 euros/m3 considering the European aid foreseen.
If a calculation of rates with discrimination by uses is established (Chart 8), starting from a maximum assumable price for irrigation of 0.15 euros/m3, this would lead to an urban public supply of 0.49 euros/m3 - a very attractive price for this usage which would still be far under the cost of desalinated water.
One of the greatest benefits of the Ebro transfer stems from its layout in the territory in corridor form. The linear arrangement of the transfer at a high altitude enables creating a “continuous” supply over the whole length of the infrastructure and also at the appropriate coordinate so as not to have to raise this later on; quite a different matter from the desalination alternative, which would require conduits and complementary elevations from the coast to the point of application.
In the Segura basin, the transfer intended to come in at coordinate 500 m snm, running close to irrigable zones (Fig. 9) and at an ideal height; it partially takes advantage of the infrastructure of the Tajo-Segura transfer and is complemented with this; it is also compatible with the main irrigation and public supply conduits. There is a possibility of dealing with the internal distribution of the Seguro using the existing hydrographic network or not, as appropriate, and with the option of providing ecological flows in its basins.
All the irrigable zones which would be supplied in the Segura basin by the Ebro transfer are in a precarious situation through the lack of a guaranteed supply, since these are supplied by overexploited aquifers. Replacing flows of waters from overexploited sources by transferred waters would enable this undesirable practice to be discarded, with the benefit meant by the natural recovery of the phreatic levels, in a slow process of natural replenishment. The final result would be the re-emergence of springs and sources and the corresponding regeneration of watercourses, brooks and rivers. The Ebro transfer thus constitutes a genuine project of environmental regeneration for the Segura basin, as put forward by the Water Framework Directive.
This possibility of environmental regeneration of the water environment of the Mediterranean coastline provided by the transfer is particularly stressed by the Berkeley report.° Said report, which gives an in-depth analysis of the hydrology and water resources of the river Ebro minimises the significances of the effects that transfer’s drawoff flows may have on the Delta precisely through their low quantity in relation to the flows of the river. What is more, this report stresses that the transfer project, with its corrective and compensation measures, is a good chance to improve the situation of the Delta (Fig. 10).
The linear layout and continuity of the transfer forming a corridor 900 kilometres long will allow the location of long-distance infrastructures, complementary or not, of power, communications and others, which may be of great strategic interest, with an environmental impact already recouped.
The route planned takes advantage to a great extent of hydraulic infrastructures already existing, minimising its impact. The effects on the Natura 2000 network are the very minimum (three crossovers of rivers and a marginal anthropised area). The project for the Ebro transfer was submitted for public information and Environmental Impact Assessment, obtaining the compulsory favourable Declaration.
The Ebro transfer is a strategic element for the supply and distribution of water in Spain and this has repeatedly been considered as such in all the strictest hydraulic studies and plans made over history. In all these earlier plans, the proposals for flows to be drawn off from the Ebro were higher than the ones considered in the NHP-2001. We could stress, amongst others, that of Félix de los Ríos (1937) and that of the Hydrographic Study Centre10 (1967). More recently it was also considered a key part of the Preliminary Project " of the NHP-1993. The project for the Ebro transfer also meets Community regulations 12 and in particular the Structural Water Framework; s whose compliance is precisely one of its aims.
The NHP discarded the widespread desalination of seawater as an instrument for providing large volumes. Certain considerations in this respect have already been put forward. Others will now be given.
The only advantage offered by desalination is that the raw material is inexhaustible and is not subject to rainfall. What some politicians consider as a great advantage of desalination, its "independence'; is not actually so, since values and practice of cooperation and solidarity are necessary in a nation
The desalination of seawater through inverse osmosis, which is the one at present being considered in Spain, is complex and requires a lot of technology. The membranes are covered by patents and depend on external technology. There have been great disappointments with desalination even in technologically advanced countries. Many examples have been seen in which the fast clogging of the inverse osmosis membranes has made the planned operating costs soar to extreme limits, as occurred with the desalination plant in Tampa'^ in Florida (United States). On the Andalusian coast there have also been major problems and a bad track record through technical, economic or management difficulties in large seawater desalination plants, as is the case of those of Costa del Sol, Carboneras, Almería and others." Consequently, the secure water supply that is in theory provided by desalination, may actually not be such if one considers the greater likelihood of failure, technical or management shortcomings, as is shown by experience.
The high power consumption of desalination, 2.5 times greater than transfer (to which one must add, where applicable, that of the relevant pumping operations) may lead to an uncertain economic situation, in the present scenario of absolutely unforeseeable, though always rising, power prices. Large-scale desalination is prejudicial for national power policy, as it contributes to the imbalance of our balance of payments, and also has a negative effect on environmental policies, making it difficult to comply with the Kyoto protocol.
The waters from desalination are chemically unbalanced, with high acidity and presence of some harmful elements, such as boron, both for the supply of towns and for crops, especially citrus fruit'° They need to be mixed with other water or more complex and costly treatments. In towns such as Las Palmas, with a high percentage of desalinated waters, the people do not drink tap water through its unpleasant taste.
The brine rejected from desalination constitutes a contaminating element through its salt concentration and its content in chemicals from prior treatment. Its pouring into the sea in large quantities as waste from large desalination plants requires a special study on impact for the environment. The increase in salinity from seawater as a result of dumping brine decisively affects some highly valuable species of the Mediterranean sea, such as the posidonia oceanica" (Fig. 1 1), very common on our coasts (Fig. 12).
The location of large-scale desalination facilities close to the coast also involves two major disadvantages. On one hand, the difficulty of locating large regulation dams as required by irrigation, if this were to be with desalinated water, and on the other, the actual territorial environmental impact of locating the plant on land with higher value such as the coast, an impact which would be considerably heightened with the need for high voltage electricity lines and transformation substations for high power.
Although it is very difficult to establish a comparative process between transfer and desalination, chart 9 shows a summary of different aspects treated.
In spite of what is stated above, major progress has doubtlessly been made in desalination technology, though still not enough for the annual provision of 1 km3 of water. In this respect the NHP considered that desalination is necessary and can solve some specific and particular problems for reinforcing supply, with a transitory nature, for periods of drought and in general to help to give a more complete guarantee, but always as a complement. Appendix II of the NHP thus included the relevant figure of 38 desalination facilities in the Mediterranean area, the islands and Melilla.
California has characteristics very similar to Spain in some aspects as regards the geography, climate, availability and uses of water (Chart 10).
In California, as in Spain, there is an imbalance between the supply and demand for resources (Fig. 13). There, these are corrected with water transfers: transfers supply 18,800 hm3/year, which represents 32 % of the total supply. Figu¬re 14 represents the main transfer plans in California, which are used both for supplying the public and for agriculture.
Desalination in California, which has a supply capacity of 13 hm3/year (representing 0.01 % of the total supplies), is done by means of 12 plants, located mainly in the south, mostly operating sporadically or inactive. Today other desalination plants are proposed in California to serve mainly coastal communities. If all the plants proposed were finally built the total supply would be about 320 hm3. That is, about 0.3 % of the total.
The case of the city of Santa Barbara is highly significant: this was traditionally supplied by surface waters, subsurface waters and reuse. From 1986 to 1991 they underwent a serious drought, which led them to build a desalination plant as a temporary emergency source and a transfer of water from the north.'9 The desalination plant was completed in 1992 and since that time (the end of the drought period) it has been on standby status. The transfer was completed in 1997 and has been running ever since. The water costs are given in chart 11.
In 2005 in California, Stokes and Horvath20 drew up a comparative study between transfers and desalination with an analysis of the integral life cycle. Charts 12 and 13 respectively give the results referring to water consumption and the emissions of greenhouse effect gases and other atmospheric contaminants. Charge 14 also shows the comparative operating costs with further data from other sources.
California’s experience comes down to the following: 1) water transfers represent the main source of water supply, 2) desalination acts as a complementary and back-up source, and 3) water transfers involve lower power consumption, lower emissions and lower associated costs than desalination.
After the execution of the NHP had started (February 2004), the new Spanish government decreed a substantial modification of this (RDL 2/2004), repealing the Ebro transfer. This was known as the A.G.U.A. programme. This extremely rushed (plan-reversing) measure was carried out without any alternative hydrological plan and with no further documentation than the five sheets of the State Gazette taken up by the relevant Decree Law, apart from two short reports, in a process utterly out of proportion with the scale of the previous planning and thus casting doubt on the technical thoroughness and correctness of what it puts forward.
To fill in the vast gap entailed by this step and justify the repeal of the Ebro transfer, the A.G.U.A. programme starts by invoking a "new water culture" (actually merely obvious principles of good management of demand and protection of the environment already envisaged in the NHP, which are now made radical with a visceral rejection of hydraulic works). Secondly, it puts all the emphasis on desalination of seawater as main source of water resource supply; that is, the main aspect of the NHP (the Ebro transfer) is scrapped, and what was only a complement in this (desalination) is now given the nature of single and main solution.
As regards the River Segura basin, the A.G.U.A. programme envisages a list (Appendix IV of priority and urgent measures) with 32 measures, which is the result of selecting 22 of the 71 measures included in the former Appendix II of the NHP, to which 10 new ones are now added (Appendix III). Two new desalination plants and action known literally as "urgent measures for supplying resources to the Al¬tiplano and Alto Guadalentín", which have not to date been defined, are worthy of mention, in the part newly added.
It should be stressed that this A.G.U.A. programme approved in Parliament has not been officially submitted for any strategic environmental assessment,2 quite contrary to its apparent environment-friendly basis. In April 2005 a report on Environmental Sustainability was presented attempting to justify the environmental correctness of the decisions made in 2004 a posteriori and officially getting the aforementioned assessment under way.
Barely one year later a second modification of the NHP has already gone through Parliament (Act 1 1 /2005), which is basically the previous Decree-Law with small alterations and a partial reform of the Water Law. In the Segura basin, this second modification introduces a new item of concern in addition to the repeal of the Ebro transfer, a reduction of the Tajo-Segura" transfer; it also adds five new measures in Appendix IV, but without any significant repercussion as regards new resources.
Figure 15 shows a comparative view of the external water resources planned in the National Hydrological Plan and the A.G.U.A. programme, which also reflects the unitary average prices for the different sources, according to what is justified herein. The conclusion drawn from this is that the forecasts for water supply in the Segura basin are considerably lower and the costs of water clearly higher by reducing precisely the cheapest sources.
With the A.G.U.A. programme the shortfall comes to about 600 hm3/year, that is 30% of the demands of the Segura: an unsustainable situation leading to undesirable confusion in water matters, progressive deterioration of the environment and a loss in guarantees endangering about 40% of the irrigable surface area, about 100,000 hectares of irrigated land.
It only provides solutions for the supply of Taibilla, thanks to its nature as a general system, though it introduces an increase in water prices with a drop in competitiveness and unfavourable socio-economic effects for regional development. As for irrigated land, the high prices of desalination only make it viable as a complementary resource (mixed waters) and also in locations close to the coast. The recovery of overexploited aquifers and other environmental regeneration measures are non-viable with desalination waters.
Chart 15 shows all the considerations in this study and reveals that the A.G.U.A. programme is insufficient and only represents a partial solution for the Segura basin.
Apart from constituting a partial solution and increasing the price of water, its application is highly likely to be delayed (the Ebro transfer was planned to come into operation in 2008). The new measures whose planning is now being attempted require definition times and technical design and administrative periods for authorisations, expropriations and public tenders which entail a delay in providing results and involve the danger of forfeiting European financing.
The Ebro transfer constitutes a key measure for hydrological planning in Spain. It is the ideal infrastructure in the short, medium and long term for catering for the large demands of water spread linearly down the Mediterranean arch. This is a technically and economically feasible project and also (an important matter) compatible with the environment. This is a project able to be extended in the future with new sources, such as water banks, the water of the Rhone25 or others. Its repeal was the greatest error in hydraulic policy in the history of Spain. The execution of this project should recommence as soon as possible.
Highly prosperous countries which have arid zones and sufficient water in other parts such as California solve their water shortages with general large capacity water supply systems, founded on conventional hydraulic works, such as dams, conduits and transfers, handled according to widely accepted criteria on which sustainable development is sustained.
Plans based on widespread desalination do not constitute an alternative to the general system of transfers due to their high economic and environmental cost. A relevant decision in this respect was recently (1995) made in London, a city in which there has been a marked change of plan ruling out large-scale desalination. Desalination may however play a complementary role in hydrological planning, if implemented in moderation and in uses for which the prices of water does not mean a decisive factor.
With a little use of pen and paper, the concepts mentioned can doubtlessly be explained quite clearly, not only from the technical and environmental standpoint, but also with pure and simple common sense, which is, with certain exceptions, within everyone’s reach.
Miguel Ángel Ródenas Cañada and Juan Guillamón Álvarez
Civil Engineers
Notes
1. Water available from the Segura. The water available from the Segura basin is under 1,000 m3/inhab/year. This marks the threshold of a “catastrophic” situation according to the report The development of water resources in the world. Water for people. Water for life, UN, Kyoto, March 2003.
2 Trade balance. The production of fruit and vegetables in the Mediterranean arch is a positive item in Spain’s trade balance. Only the Region of Murcia, with 3% of Spain’s population, represents 20% of Spain’s exports, with two million tons and 1,313 million euros (Source: FE¬12004). This is a competitive business, which does not depend on CAP subsidies, and is commercially sustainable. The main threat to it is the lack of water.
3. Limitation of extension of irrigable zones. The Segura Basin Plan considers it vital to maintain the economic and commercial structure created by the irrigated land existing at present: highly competitive irrigated farmland, necessary for EU food supply and with a territorial and environmental impact that has already been recouped. In a scenario with a serious water shortage, this premise has more guarantees of being attained with an absolute limitation of irrigable areas: the Segura Basin Plan thus imposed this very strict condition. The possibilities of fostering this activity are thus restricted to greater productivity without increasing the irrigated surface areas.
4. Economic transfers from the Tajo-Segura. One singularity of the economic-financial system of the Tajo-Segura is that the quotas received for amortization of the work are used for carrying out hydraulic works in the Autonomous Communities of the delivering basin, as compensation. From 1979 to 2004 188 million euros have been transferred for this item.
5. Financing of hydraulic works. As a general rule, for the 2000-2006 period, hydraulic works in Spain qualify for aid from the EU: Cohesion Funds in the whole national territory and ERDF funds depending on categories of regional income. For the 2007-2013 period the situation changes for Spain due to the extension of the EU. It loses the right to Cohesion Funds and aid is also drastically reduced in the Murcia and Valencia regions, which are disqualified as Objective 1 areas through exceeding 75% of the GDP/pc. To enable a uniform comparative study, this article has used the aid figures expected by the Ministry of the Environment in 2003 for the main infrastructure of the NHP, the Ebro transfer (1/3 of the investment).
6. “Libro Blanco del Agua in Spain” published by the Ministry of the Environment (1998). This is possibly the best compilation in the world on the situation of a State’s water resources. This is a real “hydraulic” photo of Spain with a "pixel" of 1 Km. x 1 km. It was drawn up from the huge amount of information prepared for the hydrological plans for the basins and updated with specific information. With widespread dissemination, it acted as a document for analysis and debate to formulate the bases of the NHP.
7. Economic optimisation of transfers. In the preliminary project of the NHP combinations of possible transfers are analysed. The optimum flow from an economic standpoint is the option chosen of the Ebro transfer, with values around 0.30 €/m', as opposed to values over 0.40 euros/m represented by other possible combinations of Ebro+Duero+Tajo.
8. Spanish Constitution. Article 45.2: "Public authorities will safeguard the rational use of all natural resources, in order to protect and improve the quality of life and defend and restore the environment, supported by essential group solidarity ".
9. Berkeley Report. A Technical Review of the Spanish National Hydrological Plan (Ebro River Out-Of-Basin Diversion) (January 2003). An independent report on the NHP and the Ebro transfer, commissioned at the request of the European Union Commission. The editing committee was selected by the EU Research Centre of the EU in Ispra (Italy). The authors are: Alexander J. Horne, John Dracup and Michael Ha¬nemann (University of California, Berkeley) l Ignacio Rodríguez-Iturbe, Princeton University 1 Edward Means, McGuire Environmental Consultants Inc., Santa Moni¬ca, California 1 James C. Roth, Private Consultant, San Francisco.
This report is a vital reference for proper knowledge of the Ebro transfer project, analysing with a thorough and wide-ranging multidisciplinary view (engineering, hydrology, ecology and economy). Its conclusion is the viability, appropriateness and usefulness of the project for solving problems of water supply and environmental problems in the Mediterranean arch. There is no substantial criticism of the project, though it does establish recommendations and measures to be performed in its implementation and method improvements on details.
10. Background to the Ebro transfer. In 1937 Félix de los Ríos, Director of the Ebro Confederation drew up a plan (with great vision and sense of the general interest) covering the transfer of 1,260 hm year of water from the Ebro for improving and extending irrigated land from Tarragona to the river Almanzora. Similarly, in 1967, the Centre for Hydrographic Studies considered the transfer of 2,800 hm3/year of water from the Ebro to the Mediterranean arch as part of a master plan for correction of the national hydraulic unbalance included in the General Preliminary Project for the Joint Exploitation of the Hydraulic Resources of the Centre and Southeast of Spain -ATS.
11. Preliminary Project NHP-1993 (Borrell Plan). What was also known as the Integrated System for National Hydraulic Balance (SIEHNA) obtained a favourable report from the National Water Board (July 1994). The synthesis of the report then sustained that "large-scale transfers (…) are vital, regardless of what the future evolution of the demands may be". This was an approach on a much larger scale than the PHN¬2001 and a real development plan (600,000 hectares of new irrigated land) rather than a sustainability project like the PHN-2001. This spread out greater pressure over the Peninsula’s water resources, mobilising two large systems, North-Duero-Tajo and Ebro. It also covered over a dozen water transfers: the overall maximum volume of the transfers envisaged was 3,353 hm' and the maximum amount to be reduced from the Ebro basin was 1,642 hm.
12. Transfer and European Union. The rumour that the EU Commission had rejected the Ebro transfer has been spread: this is false; the competence for approving the Ebro transfer rests only with the Spanish State, although the project must obviously adapt to European legislation, a question on which the EU did not make any official declaration. In December 2003 the Spanish government asked the Commission for Community financial aid for building the transfer. The Commission did not make an official statement on this matter either, since while the application was still being analysed the transfer was repealed and the relevant financing application withdrawn (2004).
13. Transfer and Water Framework Directive. It has been said that the WFD prohibited transfers. This is a falsity which furthermore reveals the absolute ignorance of its content and aims, which are quite simply the protection and recovery of the water environment. In the WFD it only mentions transfers once and not even in its articles, but in Appendix ti, section 1.4 Identification of pressures, where it states that the Member states must identify significant anthropogenic pressures, including transfers, in a long list. This is obvious and does not involve any pronouncement nor position of the Directive in favour or against these. Transfers, water supplies, irrigation systems, dams, canals, desalinisation plants and so many measures that it would be impossible to list would be on the same plane as transfers or diversions.
14. Tampa Bay Desalinisation plant. A facility promoted by Tampa Bay Water (public water agency of Florida State) to supply 10% of the water for supply in the region, which is at present supplied by surface and subterranean waters. This is the largest capacity inverse osmosis seawater desalinisation plant in the USA, with a volume of 40 hm3/ year and an investment of 110 million dollars. Its building was started in August 2001 and it has not actually started running due to serious problems in its operation. Recently (2004) a competitive tender was issued for its full alteration. (Source: "St. Petersburg Times", 2nd August 2003).
15. Large seawater desalinisation plants in Andalusia. The desalination of seawater on the Andalusia coast has involved a lot of absurd situations and failures. 1) The Marbella desalinisation plant, with a capacity for 20 hm3/year, was built in 1997 and has not yet supplied even a single hm3 as of June 2005; it is intended to go into operation in July 2005. 2) The Carboneras desalination plant, the largest desalinisation plant for seawater in Europe, with 42 hm3/year, was completed in 2002 and has only worked at 8% of its capacity. 3) The Almería desalination plant, with a capacity for 18 hm3/year, has been inactive until now although its building started in 1999; its partial start-up would seem to be planned for late 2005.
16. Chemical unbalance. The waters released by inverse osmosis, though having low conductivity, have great chemical imbalance as regards natural waters. The high boron content in desalted water is important (values over 1 mg/I), since today’s membranes still have great permeability to this element. Directive 98/83/CE (transposed by RD 140/2003) on quality criteria of water for human consumption does not allow such levels of over 1 mg/l. In farming, the main Mediterranean crop, citrus fruit, and in particular lemons, do not tolerate values over 0.5 mg/l. One should also stress the high acidity and ensuing corrosion caused by pure desalted waters: there are also other undesirable chemical unbalances for crops, such as the high sodium/calcium ratio and others.
17. Salinity Mediterranean waters have a salinity of 37.5 g/l. The brine product rejected concentrates approximately twice the salt content. The great increase in salinity causes the dehydration of the cells of the marine micro-organisms affected. Recent studies made jointly by several Spanish bodies cast doubts on the consequences that large-scale desalination would have for the seabed. These studies show that from 38.4 g/l the meadows of Posidonia oceanica would be affected, i.e., they do not tolerate variations in salinity entailing an increase over 1 g/l. The problem takes on greater relevance through the large size of the desalination plants envisaged, in which the dumping implies a volume similar to that of the water product. The meadows of posidonia form the most important ecosystem in the Mediterranean, the home of 400 plant species and over 1,000 animal species. There are 10,000 hectares of these underwater forests only in the seawater of Murcia region.
18. John A. Dracup. The experiments mentioned from California were drawn from the conference entitled "Comparison of the project for transfers from the Ebro and the A.G.U.A. Programme in the light of the experience in California", held on 5th May 2005 in Alicante and 7th May 2005 at the Royal Economic Society of Friends of Murcia, given by John A. Dracup, professor in Civil and Environmental Engineering of California University, Berkeley.
19. Santa Barbara. A city with 1.5 million inhabitants located to the northwest of Los Angeles. The water transfer supplies 48 hm3 for the county area and 3.7 hm' for the city. The desalination plant has a capacity of 3.7 hm3 and in 2000 it was the largest inverse osmosis desalination plant in the USA.
20. Stokes and Horvath, 2005. Authors of the thesis "Life-cycle Energy Assessment of Alternative Water Supply Systems". Accepted for publication in the "International Journal of LCA". The study was written on two counties in California which have desalination, transferred waters and reuse as sources of water.
21, Hydrological planning. Hydrological planning has characteristics that are highly different to other infrastructure plans. In Spain the 1985 Water Law established a full participative process, prepared from top to bottom, with the Basin Hydrological Plans by the Basin Water Boards, and the National Hydrological Plan, in which the National Water Board also played a fundamental role of coordination and participation in sectorial territorial policies, before its respective approval by the Government or Parliament. Due to its very nature, hydrological planning cannot be improvised nor even less replaced by simple legislative action. Hydrological planning constitutes the rational method to ensure general interest in the field of water. As regards the planning dictated by the Government, there may be doubts as regards how correct its aims are.
22. Environmental impact. From 21st July 2004 Directive 2001/42/CE on the assessment of the effects of certain plans and schemes on the environment must compulsorily be applied. This Directive requires environmental assessment and taking into account authorities’ and citizens’ opinions prior to approval or presentation for legislative procedure of the plan or scheme. The plans or schemes for management of water resources are subject to this rule. At present this Directive has not been transposed to the Spanish State.
23. Modification of the Tajo-Segura. The following text is inserted in the second modification of the NHP (Act 11/2005, additional provision one): "the volume transferable from the head of the Tajo will be reviewed in the future, after hearing the Autonomous Communities affected, as the government makes the investments required to meet the needs of the Segura basin.”
24. Transfer and Water Banks. Experience has shown that the instruments of the Water Law on assignment of rights to use of water and centres for exchange of water usage rights (the so-called public water banks) are useless in the internal domain of a basin with a deficit such as that of the Segura. To make these feasible there have to be connection infrastructures between basins which allow access to major “deposits” of water which may be assigned with the agreed economic consideration. The infrastructure of the Ebro transfer is the only way to make this highly interesting instrument for water management feasible, as the Ebro basin is the greatest potential "depositor' in Spain (5,500 hm3/ year total consumption, with 800,000 hectares of irrigated land which may obtain important savings through their modernisation) and the Mediterranean arch is the main demander. In practice, the repeal of the Ebro transfer strips the policy of water banks in Spain of any content.
25. Other transfers. The NHP -2001 envisaged making studies for incorporating other transfers already mentioned in the preliminary plan itself in the Spanish hydrological system to obtain new water resources in the longer term (additional provision nine of the NHP). The existence of the Ebro transfer infrastructure gives enormous encouragement to this possibility. Hence, one highly interesting example is the Rhone (a fluvial system tripling that of the river Ebro) transfer to Catalonia, where the existence of the Ebro transfer will enable increasing the guarantee or even catering for future additional demands in the southern Mediterranean arch (Valencia, Murcia and Andalusia). The repeal of the Ebro transfer ruins this possibility.
26. London desalination plants. Facilities planned in May 2004 to complement the supply for London. It was going to be the first inverse osmosis plant in the United Kingdom and would collect salt water taken at low tide in the Thames estuary. Capacity: 50 hm3/year (150,000 m3/day); budget: 326 million euros. In April 2005, the project was dropped through an excessive consumption of power, due to its cost and its impact on marine habitats. Ken Livingstone, mayor of London, declared: "l am not convinced that a desalination plant is a viable long-term way to ensure London has an adequate supply of water". It is intended to build a new dam on the upstream Thames, close to Oxford, to store the river’s winter flows; a large-scale plan for pipeline replacement has been arranged to reduce losses. (Source: www.news.bbc.co.uk).
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