SIGBIRIZ, A Tool For Regional WaterManagement In The Senegal River Delta AndLower Valley

Abstract

The Senegal River Delta and Valley (Northern Senegal) are located in the Sahelian climatic zone, which is characterized by a long dry season and a short rainy season. Due to a high evaporation demand in the rainy season and a low and irregular rainfall (around 300 mm/year), rainfed agriculture is unfeasible. Irrigation was introduced in the region in 1960 and actually 80,000 ha (mainly rice) are under irrigation in the Senegal River Delta and Valley. The irrigation schemes differ greatly in their size, layout and management level. One of the main responsibilities of the Senegalese irrigation authority (SAED) consists in supplying the required irrigation water to the main watercourses and to follow up the agronomic activities. In order to assist SAED in assessing the rice water requirement, the BIRIZ model was developed. The estimates of the daily water requirements for different probabilities of rainfall of the individual rice schemes computed by BIRIZ are based on scheme management level, evapotranspiration demand, soil parameters and crop characteristics. To monitor all agro-economic factors in the region, SAED uses a Geographical Information System (GIS). The linkage of BIRIZ with GIS forms the regional water management model GISBIRIZ. The data flow, graphical user interfaces and different modes of running GISBIRIZ to manage the water resources in the Senegal River Delta and Lower Valley are presented in this paper. This model allows SAED not only to compute the irrigation water requirement of all rice schemes in the area but also to estimate the required discharge for the different watercourses to satisfy the scheme water demands. With this tool SAED can also spot schemes having a negative impact on the environment (high water consumption, high water table recharge,...) and resolve bottlenecks between water demand and supply before the onset of the irrigation season.