Présentations Colloques

Oral Presentation
5.02
Session 5.02: Groundwater and global change
Ngom Fatou Diop
Rapid evolution of water resources in the Senegal River delta and impact on the development of Delta land.
The geological history of the Senegal River delta is linked to climate change, which, during the Quaternary, have led several phases of marine transgressions and regressions. These marine invasions led to the establishment of a body of salt water throughout the delta. The waters of this sheet are essentially sodium-chloride-type, and indicating their marine origin.**** Agricultural area par excellence, impoundment plots seems to be the cause of the accumulation of surface salts after a few years of operation. This accumulation of salts, induces secondary processes alkalizing and sodification land leading to their abandonment. This is probably related to the strong rise of the saline groundwater recharge period.**It is in this context that this study was conducted to understand the factors behind the rise of the web. It was conducted by analyzing the relationship between water intake from the river, irrigation, rain on one hand and fluctuations in the other table.**** The results showed a relationship between water intake and changes in the water table. This influence is particularly felt in the agricultural water due to irrigation water intakes. This rise of the salt layer (the salt concentrations exceeding those of sea water) and participates in the degradation of cropland. This occurs due to evaporation which causes a deposit of salts overground due to the proximity of the web.**** This back up of the web is, however, linked to insufficient drainage of irrigated plots, including deep drainage which should lessen the groundwater recharge and unclog plots. Thus, it was proposed, in terms of alternatives, deepening drainage channels to fold the table. This, by lowering down the line of zero flux (pass line of water from the liquid phase to the gas phase), would, no doubt,to the cessation of accumulations of surface salts. ******
Senegal