A Contribution to an Advisory Plan for Integrated Irrigation Water Management at Sidi Saad Dam System (Central Tunisia): From Research to Operational Support

Abstract

In the agriculture sector, combining physically based soil water balance and simulation models with GIS (Geographic Information System) tools is of a considerable interest to manage the available water amount. Indeed, this combination can enhance water supply management, optimize agricultural catchments management and study impact of management intervention from small scale (plot) to a larger one, such as irrigated district and/or region. This work presents the case of Sidi Saad Dam System (central Tunisia). The main objectives were (1) to create a specific GIS data base for the four irrigated districts of the area (Sidi Mansour, Sidi Saad, Fjij and Touila) based on the characteristics of cultivated crops, soil types and used irrigation systems; (2) to assess spatial and temporal variation of soil water budget terms from plot and farm levels to irrigated district and regional scales; (3) to map results for different time steps. The achievement of these objectives was made possible using the WEAP-MABIA Model. Thus, daily Penman--Monteith reference evapotranspiration (ETo), effective precipitation (PE), crop water requirement (CWR), actual crop evapotranspiration (ETa) and irrigation water requirement (IWR) were estimated for the four irrigated districts using spatially distributed parameters on climate, crop, soil characteristics, irrigation system and basic irrigation management practice during the cropping season 2014/2015. The delivered information is maps of the Sidi Saad Dam System with its four irrigated districts and their related farms and plots; representing the current land use, the water consumption at farm level; the crop water requirement (CWR) and the irrigation water requirement (IWR) at a daily, weekly, monthly and yearly steps. Also and thanks to WEAP (Water Evaluation And Planning system) tool functionalities, these results can be displayed on Google Earth and shared between all water irrigation managers.