Coupled hydrological-economic modelling for optimised irrigated cultivation in a semi-arid catchment of West Africa

Abstract A coupled model system, consisting of a distributed hydrological model and an economic optimization model, is applied 1) to investigate regional interdependencies between irrigated agriculture and regional water balance and 2) to identify optimized cultivation strategies. The coupled model system is applied to a case study for the semi-arid Atankwidi catchment in West Africa. The hydrologic, physically based model WaSiM is used to simulate the water balance considering a fictive reservoir and a fictive irrigation system. The economic optimization of crop cultivation is perfromed by a nonlinear optimization model GAMS-ECIM which is coded in GAMS (General Algebraic Modeling System). The GAMS-ECIM uses a nonlinear optimization solver to identify economically optimized cultivation strategies under certain hydrological conditions. The coupled model system is designed as decision-support tool for local authorities and agricultural stakeholders in the Ghanaian Upper East Region (UER). Hella Ahrends (University of Bern, Institute of Geography, Switzerland); Markus Mast, Harald Kunstmann (Institute for Meteorology and Climate Research, Forschungszentrum Karlsruhe, Germany); Charles Rodgers (Centre for Development Research (ZEF), Bonn University, Germany)