Optimisation to assist IWRM and conjunctive water use

This paper presents an integrated water resources optimisation (IWRO) model that was developed to manage the conjunctive use of surface and groundwater resources. The IWRO model utilises a genetic algorithm approach in which a surface water systems simulation model and a finite-difference groundwater model are used as evaluation functions. The objective is to achieve equitable water allocation within environmental sustainability constraints. The approach was evaluated through application to the irrigation systems in the Shiyang River basin (SRB) in Gansu province, China. The SRB has been under severe water stress and was experiencing a rapid decline in groundwater levels. Results produced with the IWRO model are compared with those of a previously existing simulation model of the basin for a business-as-usual scenario. The IWRO model produces an equitable water allocation that is sustainable.