Two-Dimensional Numerical Simulation of the Hydro-Sedimentary Phenomena in Lake Taabo, Côte d’Ivoire

In Côte d’Ivoire, most of the reservoirs built to improve water supply, electricity, agriculture and cattle no longer work because of silt deposits and euthrophication. This study aims at modeling the hydro-sedimentary functioning of Lake Taabo in order to understand the sedimentation phenomena taking place. In this survey, 204 water samples and 31 bottom sediment samples were taken, during different hydrological seasons, to estimate suspended sediment concentrations and characterize the bottom sediments of Lake Taabo. The study showed that suspended solid variations are related to hydrological seasons. During dry seasons, the lake is lightly loaded; the average concentration is 7.89 mg/L. At the other end of the scale, during rainy seasons, suspended sediment concentrations increase and the average concentration is around 16.30 mg/L. The bottom of the reservoir mostly consists of mud. Sands are found near the islands and the dam. Sand size varies from medium grain to coarse. The average grain size is 451.48 μm. The hydro-sedimentary environment of Lake Taabo was simulated by a transport model, coupled with a hydrodynamic model. The various simulation scenarios indicated that Lake Taabo is subject to 20 to 60 mm of annual deposits. The greater thicknesses were observed near the spillway and the power intake.     

What role for law in achieving transboundary drainage basin security?--the development and testing of the Legal Assessment Model (LAM) for transboundary watercourse states.

The beneficial use of the world's transboundary waters raises difficult issues for drainage basin security on most parts of the globe. International law provides that each transboundary watercourse State is entitled to, and obliged to ensure, an "equitable and reasonable use" of these shared waters. The IWLRI developed and tested a Legal Assessment Model (LAM) through the work of interdisciplinary teams working in three different transboundary situations--China (upstream), Mozambique (downstream) and Palestine (shared groundwater). The LAM provides a tool for transboundary watercourse States to use in the preparation of their national water strategy for use at the national and international levels. The model should now be tested at the basin level, with a view to assisting to accomplish the peaceful and rational use of transboundary waters in line with the governing rule of international law and thereby to facilitate the overall policy objective of drainage basin security.