Spatial-temporal differences in in-stream flow requirement based on GIS:A case study of Yan''an region, northern Shaanxi
基于GIS的河流系统生态环境需水时空差异分析——以陕北延安地区为例

Although water has the central function of the bloodstream in the biosphere especially in arid or semi-arid regions such as Yan’an region in northwestern China, yet the very limited attention is paid to the role of the water-related processes in ecosystem. In this re-search, based on continuous nearly 50-year data including runoff volume, sediment discharge as well as sediment accretion from hydrographic stations, and 10-year information of water quality from pollution monitoring stations, the method for measuring in-stream flow requirement has been put forward supported by experiential models and GIS spatial analysis. Additionally, the changes of in-stream flow requirement for environment and economic development have been addressed from spatial-temporal dimensions. The results show that: (1) According to the central streams in Yan’an region, mean annual in-stream flow requirement reaches 1.0619 billion m3, and the surface water for economic exploitation is 0.2445 billion m3. (2) Mean annual in-stream flow requirement for sediment transfers in flood period occupies over 80% of the integrated volume in a year. (3) From the 1950s to 1970s, in-stream flow requirement for sediment transfers is comparatively higher, while from the 1980s to 1990s, this requirement presents a decreasing tendency. Foundation: National Natural Science Foundation of China, No.40771019; Innovation Foundation of Shaanxi Normal University Author: Wang Lixia (1979–), Ph.D Candidate, specialized in water resources and GIS.