Calculation of Rice Water Requirements Using the FAO CROPWAT 8.0 Model in the Hydro-agricultural Development of the Agricultural Development Center (CDA) of the Urban Commune of Diffa

Abstract

This agrohydrological study An analytical study conducted at the Agricultural Development Center (CDA) in the Diffa commune (Diffa region, Niger) aimed to analyze the interactions between soil physical properties, climatic parameters, and irrigated rice farming data in order to estimate water requirements and optimize irrigation planning using the CROPWAT 8.0 model. The climatic and edaphic data used cover a dry season. Soil properties (clay-loam texture, water retention capacity, percolation) were characterized to assess their influence on water dynamics, while climatic parameters (temperature, relative humidity, wind, sunshine) were used to calculate the reference evapotranspiration (ET0). Rice farming parameters, with a transplant carried out on February 25, were integrated into the model to estimate crop evapotranspiration ( ETc ), effective rainfall, and net and gross irrigation requirements. The results show that, despite good water retention capacity, significant losses through percolation (423.5 mm) reduce the potential efficiency of irrigation. Evaporative demand is particularly high between April and June, with temperatures exceeding 45°C, while the annual effective rainfall (288.4 mm) covers only a small portion of the water requirements. Total evapotranspiration ( ETc ) reaches 1,178.3 mm for only 16.3 mm of available rainfall, and the net irrigation requirement is estimated at 1,506.8 mm, or 15,068 m³/ha, confirming the near-total dependence of rice cultivation on irrigation. These results highlight that the productivity of irrigated rice in Diffa depends above all on controlled water management, requiring optimization of leveling, reduction of losses by percolation and rigorous irrigation planning in order to guarantee the sustainability of rice cultivation in a Sahelian context.