Abstract: The Water Evaluation and Planning(WEAP)model is applied to the itiaoxi watershed for an integrated water resources management study.The calibrated WEAP model is used to study the issues concerning the water quality and safety in the watershed for the period 2001-2020.The study includes the ecological function of river systems,quantification of future water demand,as well as sustainable water management practices.Problems associated with the current practices of water management are identified.The study finds that the water quality parameter total nitrogen(TN) is a restrictive factor that affects the safety of water supply in the riverhead protection zone.While,TN and total phosphorus(TP) are the factors that regulate the water function in the middle to lower reach of Xitiaoxi River.We propose that a good and efective integrated water management practice over a watershed should include wastewater treamtent plants,water saving devices,as well as implementation plans for conversion of farm land to forests to reduce the concentrations of TN and TP in the river system.Such a reduction in TN and TP concentrations could ensure the water quality and function in the entire river system meeting the III level standard throughout a year.