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Delta Blues

June 2004

Was Spain right to abandon its Ebro River development project?

Delta blues

Spain has abolished a controversial plan to dam and divert the Ebro River. Citing environmental and financial reasons for this change of heart, the Spanish government now aims to construct new coastal desalination plants, in an alternate effort to address growing water shortages.

Following a change of government earlier this year, controversial plans to radically modify the hydrology of the Ebro River have now been abandoned. The scheme – originally approved three years ago - aimed to build more than 100 new dams and hundreds of kilometres of irrigation channels to assist with the transfer of 100 billion litres of water per year from the northern reaches of the Ebro River to the more arid south-eastern regions of Spain.

Rising in the Cantabrian Mountains and flowing south for nearly one thousand kilometres into the Mediterranean Sea, the Ebro is the longest river in Spain, and has an extensive history of water management. Over the past 50 years, many dams have already been put in place, considerably reducing the level of silts carried by the river. Damage has been caused, in turn, to the Ebro Delta, a depositional landform that is dependent upon the continual arrival of new fluvial sediments.

The Delta is a valuable agricultural area, and a huge nature reserve of international importance (it is one of the main staging posts for migratory birds moving between northern Africa and western Europe). Conservationists are understandably delighted by the news that the controversial scheme has been cancelled, as many believed that it would have caused the delta to disappear altogether.

Delivering the Water Framework Directive

Deemed as being contrary to sustainable development objectives, numerous efforts had been made by many environmental and other NGOs to block European Union (EU) funding for the project, since it was first announced in 2001. Although the EU was supposed to finance 40% of total costs, the NHP arguably contradicted the new EU Water Framework Directive which calls for environmentally sensitive catchment management in all member states. (See 'It's only water: who cares?')

Why were so many dams planned along the Ebro?

Spain, in common with other Mediterranean countries, is characterised by its scarcity of water resources. Dam-building along the Ebro was to form the central plank of Spain’s proposed new National Hydroelectric Plan (NHP). Regulation of water resources was, quite simply, to be achieved by making transfers from those river catchments that have a water excess to those that experience an annual water deficit. Originally adopted by the Spanish government in June 2001, the highly controversial NHP called for the building of 120 new dams along the Ebro, from which huge water transfers could be made to the dry south-east of Spain. The HNP called for the transfer of 1,050 cubic hectometres of water per year to be made towards:

  • Catalonia (190 cubic hm)
  • Comunidad Valenciana (315 cubic hm)
  • Murcia (450 cubic hm)
  • Almeria (95 cubic hm)

190 cubic hm was also to be given to the urban area of Barcelona, with the remaining transferred volumes reserved for other agricultural areas with "irrigation rights" in the south-west of Spain. Now, however, these plans have all been abandoned (source: Water Net).

How would dam-building have impacted upon the physical environment of the Ebro River?

Changes to the flow of the river impact directly upon the Ebro Delta. This unique-looking, triangular-shaped landform covers 320 square kilometres, and is one of the most important wetlands in Europe, home to 350 species of bird. In 1983, it was even designated as a Natural Park, with the specific aim of preserving its ecosystem.

Delta facts

  • Deltas sometimes develop at the mouth of a river when the supply of river sediment is greater than the rate at which it is removed by marine processes such as longshore drift.
  • The process of flocculation aids the development of this landform. When fresh and salt water mix, clay particles become electrically charged and combine together, becoming heavy enough to fall out of suspension. In contrast, in fresh water, tiny clay particles remain in suspension even at very low discharge, as the Hjulstrom curve demonstrates.
  • Delta formation can be modelled using systems theory, with the delta itself functioning as a sediment store which is subject to inputs and outputs and exists in a state of dynamic equilibrium.

Located on the east coast of Spain, the delta has been created by the deposition of Ebro river sediments over centuries, with the Fifteenth and Sixteenth centuries widely regarded as a period of accelerated growth. The delta began growing rapidly during these years as a result of the widespread deforestation of the river basin. This was a result of fires (frequent in a semi-arid climate), growing population pressure, and the mass felling of trees for building construction and also to supply timber for Spain’s formidable navy. Run-off would have brought greatly increased inputs of soil and sediment into the river system during these years, thereby contributing to the growth of the delta.

However, parts of the delta are now eroding because the supply of sediment has already seen a dramatic reduction due to Twentieth Century dams built upstream on the Ebro River and several of its tributaries. Accretion (building) rates of fresh sediment on agricultural land, prior to the construction of the existing dams in the Ebro watershed, ranged from between 3 to 15 mm per year. Presently, more than 99 % of total river sediments are retained in reservoirs behind the dams, and the delta’s agricultural land is losing about 0.2 mm per year due to this fall in input levels. The stocks that have built up behind the dams are equivalent to a sediment thickness over the deltaic plain of about 50 cm! In places, as a consequence, the delta has regressed by 100 metres. The NHP, if it had proceeded, would undoubtedly have quickened the rate of recession.

Lower river discharge would have intensified another existing problem, namely that of salt wedge growth. Sea salt water began to penetrate further and further up into the river Ebro, as its flow was reduced during the Twentieth Century. Dam building and abstraction of water for agricultural, urban, industrial and energy use have all contributed to a lower discharge than in the past. As a result, heavier salt water now forms a “wedge” which drives upriver below the fresh water. This salt wedge regularly reaches Amposta, 25 km from the river mouth, thereby modifying the distribution patters of fresh water fish and other organisms that cannot tolerate saline conditions.(Source: C. Ibanez “The Ebro Delta, Spain: water and sediment management in the context of relative sea level rise” University of Barcelona).

What are the human costs of river management?

Management of the Ebro already brings benefits to many communities in the semi-arid south of Spain. Existing dams and irrigation schemes guarantee more regular water supplies throughout the year than in the past for many rural communities. However, there are observable costs associated with existing works. These would all have worsened had the NHP proceeded, and include:

  • Salinisation of rice fields and citrus fruit crops The reduction in the volume of fresh water as a result of existing dams and irrigation schemes has lead to an increase in the penetration of salt water in the estuary of this river, as explained above. As a result of the growth of the salt wedge, water that is drawn from the river for irrigation in its lower course is actually tapping into this saline incursion, leading to agricultural land becoming contaminated with salt. This can lead to reduced crop yields for rice growers (who cover 60 % of the delta) as well as for citrus fruit farmers.
  • Decline of the fishing industry The salt wedge does not mix with the better oxygenated fresh water above. Today, as a result, fish stocks have fallen, because much of the river water is salty and lacks oxygen.
  • Forced migrations In the last century, about 4,000 people have been forced to leave their homes and 30 villages have been emptied and flooded as a result of dam construction.

Is desalinisation the way forward?

Following the rejection of plans to divert and dam the Ebro, what alternatives exist to help Spain meet its water needs? Lacking any other alternative, the newest water plan involves building giant desalination plant along the south coast, close to where the water is needed. Around 15 plants will be needed to provide the same amount of water as the Ebro scheme would have provided. Environmental groups that campaigned against the Ebro plan have said they prefer desalination as an alternative but still foresee problems, notably the disposal of the vast amounts of residual salt that need to be extracted from sea water in order to make it drinkable.

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