Source of the research subject: The research subject was entrusted and supported by Bureau of Hydrology and Water Resources, Xinjiang Uygur Autonomous Region.

　　Study period: From November 1997 to 2004.

　　Award: The research subject won a Third Award of Scientific and Technological Progress of Xinjiang Uygur Autonomous Region in 2004.

　　Main accomplishing scientists: 1 Chen Yaning, 4 Li Weihong

　　Brief introduction of the research subject

　　Based on considering the actuality and features of soil erosion in west China, in the research subject the theoretical study on comprehensive improvement of small drainage basins was systematically carried out, the theoretical application and practice were undertaken in three typical regions including the Tianshan Mountains in Xinjiang, Loess Plateau and Qinghai-Tibetan Plateau, the research content was based on considering the needs of entironment regeneration in Development of the West Regions, and the research subject is of important significance for regenerating and improving the entironment in the mountainous regions in west China. Theoretically, landscape ecology and ecosystem management were applied in the drainage basin improvement, the integrated diagnostic method of ecosystems in the drainage basins was put forward, the decision-making supporting system of drainage basin improvement was developed, the hydraulic laws and the model of soil erosion in the drainage basins were systematically researched, the theoretical principle of comprehensive drainage basins improvement was enriched, and the important technical support for controlling soil erosion and drainage basin management was provided. Three typical drainage basins with different geologic and geomorphologic features were selected, the diagnostic results of soil erosion and existing problems in drainage basin management were integrated, the techniques of comprehensive improvement of the researched drainage basins were applied in production practice, the solutions of some difficulties, such as the limitation of theoretical technology in different regions, were found, the theoretical application space was expanded, the intuitionistic and exercisable exemplifications of regenerating and improving the entironment in the mountainous drainage basins in west China were provided. In implementing the comprehensive improvement of the Toutun River Basin, the silt discharge to the Toutun River Reservoir was effectively reduced by building sand-catching dams and planting ecological forests for water and soil conservation, and the entironment in the drainage basin was improved. After carrying out the hydraulic calculation and scientific analysis of filling-up in the reservoir, the model of giving attention to restoring storage capacity of the Toutun River Reservoir and controlling flood was put forward, scouring and silt-filling reduction of the reservoir were successfully implemented, and the storage capacity of the reservoir was increased from 5.8×106 m3 before implementing the project in 1999 to 1.436×107 m3. The study results have high pertinence, the technical scheme has strong maneuverability, and they can be extensively applied in the comprehensive improvement of small drainage basins in the mountainous regions in west China.