The good, the bad and the muddy?
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CTA. 1999. The good, the bad and the muddy?. Spore 80. CTA, Wageningen, The Netherlands.
Permanent link to this item: http://hdl.handle.net/10568/48356
Irrigation works, and dams in particular, rarely meet their objectives. Worse still, they have a mainly disastrous impact on the environment and local communities. In river estuaries, the reduced flow of fresh water into the sea means that salt...
Irrigation works, and dams in particular, rarely meet their objectives. Worse still, they have a mainly disastrous impact on the environment and local communities. In river estuaries, the reduced flow of fresh water into the sea means that salt water reaches inland more easily. In delta areas, gravel and salt deposits impoverish the land. As well as soil degradation, water-borne diseases, removal of communities, and loss of flora and fauna make entire areas less fertile and more hostile. It is as if Nature was taking revenge for having her hand forced to behave differently. Or is it the hand of humankind which is wreaking the damage? At the end of the day, the issue is about who, in a context of global priorities, is in charge of water supply, storage and distribution. The world and the dam: she loves me, she loves me not? Building dams is based on a foundation of noble intentions ; they include electricity production, improved water flow to ease river navigation, flood control, and mitigating the effects of drought. Yet when, in 1995, the World Bank annulled its financial commitments to India for the construction of a gigantic dam on the Narmada river, it was responding to a massive wave of opposition from scientists, international associations and millions of Indians who refused to allow the re-settlement of local communities and the environmental damage that this project would entail. During the same period, controversy grew all over the world about the ecological impact of the Chinese dam of the Three Gorges. And it is almost ten years since the salt-water barrier dam in Diama, at the mouth of the Senegal river, started to dry out the largest estuary of West Africa, between Nouakchott (Mauritania) and Saint-Louis (Senegal) There are examples galore, backed up by technical studies, that dams have serious effects for the economy, the environment and the health of local people. Falling investment The negative impact of dams, and irrigation projects in general, lies behind falling levels of investment in this sector (see box). Other aspects play a role too : the rising costs of construction, disappointing results of irrigation and lower prices for agricultural products. Funding levels were at their peak in the mid-1970's (when investment by the international donor community averaged USD 3 billion a year), and they have dropped considerably over the last twenty years. The World Bank now invests less than USD 1 billion annually, and total investment by donors is less than USD 2 billion a year. Only 12% of the World Bank funds in this sector are allocated to Africa. The costs of irrigation projects on this continent, however, are higher than elsewhere, for several reasons. Often reservoirs have to be built to regulate the flow of water. The projects are often in isolated areas, with resulting high costs of transport. There are not enough trained engineers for planning and for managing sites and suppliers of services and materials. This work must sometimes be contracted out, which is expensive. The final reason, and worst contributor to cost-increases of all, is the tendency of architects to oversize their showpieces, with more interest in prestige than efficiency. Viable solutions needed for now, and the next 15 years In Africa, 95% of agriculture is rain-fed (see Spore 74: Water), but this type of agriculture is not going to be able to meet growing needs for food. The FAO has warned that if current and planned irrigation programmes are slowed down, then millions of farmers will set up unsustainable systems of cultivation in arid zones, and this would lead to destructive land use. Thus investments have to be made now to meet irrigation needs for the next fifteen years. Their viability will depend on several factors: better use of geological, hydrological and topographical data; use of local materials; global planning of irrigation projects; encouraging local qualified enterprises; selection of nearest and most competent suppliers of the required level of service. Similarly, these investments can only be viable if optimal macro-economic conditions are in play (economic liberalisation, reforms) and if there is progress in agricultural techniques in improving irrigation outputs which enable accelerated agricultural production. Finally, experience has taught us that excellent results can be obtained ? when the tasks of management and maintenance of irrigation works are shared with, or even transferred to, the farmers concerned. The right levels Progress in computer technology, in remote-sensing by satellite and research will make it possible in the future to better measure water resources and needs, and thus to better design and manage hydro works. In the meantime, common sense could help us progress quite a lot now. Sustainable development means, amongst all other considerations, finding a balance between the exploitation of water resources, and environmental factors. A certain flow of water has to be maintained in a river (see box) for the sake of the health of the river and associated ecosystems, which are always endangered by the concentration of pollutants when water levels drop. Two other aspects to be integrated in projects which exploit water resources are the protection of the upper reaches of rivers (the source of much of the water flow) and the essential role played by water catchment areas, especially in high, upstream areas. There are several ways to minimise damage to them: reforestation in the higher areas will slow down floods, better control of human activities will reduce damage to catchment areas, and a fair share of gains and losses between upstream and downstream areas. In fact, the total amount of water in a catchment area, both surface and groundwater, should be seen as one overall resource, of value to downstream and upstream areas. For this reason, any hydro works can best be sited in the catchment area. The FAO has stated that catchment area authorities should be empowered to properly apply rule of best practice, which would result in less need to store water, more available groundwater, and less risk of flooding and sedimentation. Stopping degradation of irrigated land At present, between 60 and 80 millions hectares of irrigated land in the world are subject to silting and salinity. This extent of land degradation could be halted and reversed through improved irrigation techniques such as building filtered drainage networks, washing away salt deposits in the soil and through land tenure measures which make soil improvements possible. There is now considerable experience in many countries in planning and implementing irrigation works. When coupled with sensible macro-economic reforms, this experience will surely open up a new era full of promise for efficient exploitation of the world's waters. Source : Successful approaches in water development, 1996 FAO, Via delle Terme di Caracalla 00100 Rome, Italy http://www.fao.org/wfs/final/e/volume2/t07b-e.htm World Commission on Dams PO Box 16002 Vlaeberg, Cape Town 80185 South Africa. Fax: +27 21 426 0036; email: email@example.com Reading: Silenced Rivers : The Ecology and Politics of Large Dams, by P McCully. International Rivers Network 1847 Berkeley Way, Berkeley, CA 94703 Fax: 510 848 1008 E-mail : firstname.lastname@example.org Price 28$/ e25.40. http://www.agricta.org/Spore/spore80