Sustainability Assessment of Large Irrigation Dams in Senegal: A Cost-Benefit Analysis for the Senegal River Valley

Abstract

Starting in the 1970s, the Senegalese Government invested in the development of irrigated schemes in the Senegalese part of the Senegal River Valley (S-SRV). From that time to 2012, the irrigated schemes increased from 10,000 to more than 110,000 ha. In the meantime, the economic viability of these schemes started to be questioned. It also appeared that the environmental health and social costs might outweigh the benefits of irrigation. Using a life cycle assessment (LCA) approach and project cost-benefits modeling, this study (i) quantified the costs and benefits of the S-SRV irrigated rice production, (ii) evaluated the costs and benefits of its externalities, and (iii) discussed the irrigated rice support policy. The net financial revenues from the irrigated schemes were positive, but not their economic equivalences. The economic return rate (EER) was below the expected 12% and the net present value (NPV) over 20 years of the project represented a loss of about US$-19.6 million. However, if we also include the project's negative externalities, such as the reduced productivity of the valley ecosystems, protection cost of human health, environmental degradation, and social impacts, then the NPV would be much worse, approximately US$-572.1 million. Therefore, the results show that to stop the economic loss and alleviate the human suffering, the S-SRV development policy should be revised using an integrated approach and the exploitation technology should aim at environmental sustainability. This paper may offer useful insights for reviewing the current Senegalese policies for the valley, as well as for assessing other similar cases or future projects worldwide, particularly in critical zones of developing countries.

Intermediate Host Snails of Human Schistosomes in the Senegal River Delta: Spatial Distribution According to Physicochemical Parameters

“…The strong eutrophication noted on the biotope particularly to Ndellé Boye would come from the important contents of nitrates and phosphates in the water. In addition, the presence of the Diama Dam and the association of Intermediate Host Snails of Human Schistosomes in the Senegal River Delta: Spatial… DOI: http://dx.doi.org /10.5772/intechopen.85842 dikes reduce the oxidation and flow velocity of the valley water [15]. These facts, combined with waste dumps around the villages and cities and agrochemicals from irrigated fields, accelerated eutrophication of water in the Senegal River Valley.…”

Agricultural Innovations to Reduce the Health Impacts of Dams

“…By retaining water and slowing flows, dams encourage the growth of often-invasive aquatic vegetation [41,42]. Additionally, the agricultural expansion and intensification facilitated by dams likely increases fertilizer use in the landscape, which runs off into water sources and further promotes the growth of aquatic vegetation.…”

Durum Wheat (Triticum durum Desf.): Origin, Cultivation and Potential Expansion in Sub-Saharan Africa

“…The irrigable agricultural land of Senegal is divided along three rivers, (in order of importance): Senegal, Faleme and Casamance, thus providing a total estimated irrigable land of 350,000 ha [88]. The Senegal River valley alone accounts for 240,000 ha of potential arable land [89], of which 110,000 ha are currently used for rice cultivation. Since 2017 small-holder farmers started growing improved heat tolerant durum wheat varieties after completion of the rice harvest, during the winter season, which is typically left at fallow.…”