Lake Guiers is one of the major distributaries of the River Senegal. It is located on the right bank of the river, in the delta region, between latitudes 16’23 N and 15’55 N, and longitudes 16’12 W and 16’04 W, on the downstream of the Ferlo hydrological Basin. In this study, Lake Guiers Basin and Ferlo Basin refer both to the same thing (figure.2). It’s a huge basin of 45,119 square kilometers (km2). According to Tarnavsky et al. (2013) it covers approximately 43,280 square kilometers (km2) and for Barron et al. (2007), it is estimate to 22,330 square kilometers (km2). It spreads between the region of Saint Louis and Louga.