VALIDATION OF CONCEPTUAL HYDRO-SALINITY MODEL (CIRFLE) FOR THE IRRIGATED AREA OF KALAAT EL ANDALOUS IN TUNISIA

Abstract

A simulation study of the volume of water, salt concentrations and loads in irrigation return flows was carried out in the irrigated area of Kalaât El Andalous during three hydrologic years (2007/2008, 2008/2009 and 2009/2010) using a Conceptual Irrigation Return Flow hydrosalinity model considering the Leaching Efficiency of salts (CIRFLE). Results show that the measured and calculated values are in good agreement. Scenario-analysis for management variable (irrigated area) and environmental parameters (precipitation) were performed. A good correlation between measured and calculated values was observed specially in the case of an average year (487 mm). Results show that in the case of wet year (800 mm), leaching of soil is operated naturally. So the leaching fraction can be reduced. However, if rainfall is low, there is a risk of salts accumulation in soil. In an average year (rainfall = 500 mm), if we project to irrigate the entire area (2905 ha), the water volume of surface irrigation return flow becomes very important (16. 106 m3 ). In such situation, the salt concentration of drainage water is increased by 12% and the mass of salts removed is very high (106 801 tons). In this case, there will be no risk of salinization.