Abstract: The ecological compensation of water resources in basin is an essential measure to promote the protection of local environment and the sustainable development of regional economy. Here, we applied remote sensing, GIS, and soil and water assessment tool (SWAT) to explore the problems and solutions related to horizontal ecological compensation of water resources in Qiongzhong LiMiao Autonomous County, an ecological core area of central Hainan. The GIS watershed structure analysis and overlay analysis were conducted to delineate the boundaries and scopes of Wanquan River basin, Changhua River basin and Nandu River basin in the lower reaches of Qiongzhong, and to identify the spatial relationships among counties (cities) within each basin. The subject components of ecological compensation implementation were further clarified. By using the SWAT hydrological model, the calculated mean total water supply to the downstream counties (cities) from Qiongzhong County was 4.373 billion cubic meters per year, and the water transfer from Wanquan River basin, Nandu River basin and Changhua River basin accounted for 74%, 14% and 12% of the total water supply, respectively. Based on the input accounting of a number of water environment ecological protection projects such as afforestation, comprehensive improvement of rural environment and water source protection as well as the opportunity cost calculation under the “two suspensions” policy implemented in Qiongzhong County, a cost-based mathematic model of the total amount of horizontal ecological compensation for water resources of Qiongzhong County was constructed. By considering basins first and then counties (cities), the compensation sharing distribution model was constructed based on the indicators of water supply for each basin and production water consumption for each downstream county (city). The horizontal ecological compensation shared by the downstream counties (cities) was calculated. Our results provide useful reference for the implementation of horizontal ecological compensation for water resources in river basins.

Key words: eddy covariance, ecosystem carbon exchange, carbon sink, Artemisia ordosica shrubland.