Optimum Sustainable Water Management in an Urbanizing River Basin in Japan, Based on Integrated Modelling Techniques

In this research, a Decision Support System (“DSS”) was developed, using a combination of various existing models for Integrated Water Management (“IWM”). This DSS is then applied to a small urbanized basin, the Taguri-River basin in Japan. In developing the DSS, different existing dynamic and steady state models were combined. These models include a rainfall-runoff analysis model, two river analysis models, a groundwater analysis model, and a geographical information system (“GIS”). The DSS was developed based on three basic elements: Database, model base, and tool base. A data exchange architecture was chosen and then exchange programs were written that are to act between different water analysis models in order to adequately translate the data format for each respective model. To improve the overall water condition in the basin, the DSS was used to simulate ten different measure-scenarios for the focus basin. These scenarios consider land use, ground water level, allocation of drainage system, sewerage, water quality and quantity. During the research it became evident that a combination of measures is most effective for the basin, and accordingly such combination of measures was also simulated with the DSS. Finally, this paper describes the uncertainties of the DSS and discusses its further practical applicability.