The concept of driving force-state-response (DSR) framework was used to identify and develop the assessment model of water-land environment carrying capacity (WLECC) for a river basin. The river basin water-land management (RBWLM) decision support system was developed, based on the assessment model of WLECC, as a decision making tool. The Chung-Kang river basin, located in northern Taiwan, was used as a case study to generate a sustainable water-land management strategy. This strategy simultaneously derives the optimal solutions for land use management, water demand allocation, and water quality management. Furthermore, the sustainable WLECC can also be obtained. The WLECC can be used as the area-based indicator of sustainability to accurately measure the progress towards sustainable development for a river basin.