基于生态保护目标的疏勒河中游绿洲生态环境需水研究

以疏勒河中游绿洲为研究对象,基于RS和GIS技术,选择1990年、2000年和2013年Landsat TM/ETM影像解译成果作为中游绿洲生态演变研究的基础资料,并确定了中游绿洲2020年和2030年生态保护目标。根据疏勒河中游绿洲生态环境需水特征,建立了基于天然植被、河流、湿地和防治耕地盐碱化的疏勒河中游绿洲生态环境需水定量化模型,并估算了现状和保护目标下流域中游绿洲生态需水量,从而为区域水资源合理配置和生态系统的协调发展提供参考依据。通过计算得出了疏勒河中游绿洲2013、2020和2030年天然植被、河流基本生态、河流输沙、河流渗漏补给、水面蒸发、湿地生态和防治耕地盐碱化生态环境需水量。同时得出疏勒河中游绿洲2013、2020和2030年疏勒河中游绿洲最大、最小和最适生态环境需水量分别为7.42×10~8、7.09×10~8、7.29×10~8,8.24×10~8、7.91×10~8、8.11×10~8m~3和9.12×10~8、8.79×10~8、8.99×10~8m~3。2013、2020和2030年疏勒河中游绿洲生态环境需水量年内变化主要集中于5—8月,累积生态环境需水量占全年的比例分别为58.01%、58.08%和58.13%;疏勒河中游绿洲生态环境需水量瓜州所占比例相对较大,玉门相对最小,敦煌介于二者之间。

Study on eco-environmental water requirement in the middle-reach oasis of Shulehe River Basin based on ecological protection target

The study of eco-environmental water requirements is the hotspot of ecology and water science. It is also the basis of the rational allocation and sustainable utilization of water resources. The results of such a study could provide guidance as to the optimal allocation of regional water resources and utilization, and ultimately provide a regional, economical, ecological, and environmental water system of balanced and sustainable development. The eco-environmental water requirements of an arid inland river basin are a key scientific problem facing the reasonable allocation and management of water resources as well as the eco-environmental protection and construction of arid regions. The Shulehe River Basin, as the third largest inland river basin in Hexi Corridor, Gansu province, is an important ecological security barrier for northwestern China. Recently however, increasing human activity and global climate change has led to a series of ecological and environmental issues and water crises in Shulehe River Basin. Specifically, the degenerated vegetation caused a rapid decline of the groundwater water table. In recent years, ecological water requirements have often been overshadowed by the socioeconomic use of water. This led to great changes in the oasis of the middle reaches. The oasis of the middle reaches, as a societal, economical, and human activity main zone, is a vital ecological subject for protection in the Shulehe River Basin. Considering these issues, this study utilized the oasis of the middle reaches of Shulehe River Basin as its study area. Using Remote Sensing (RS) and Geographic Information System (GIS) technology, the results of Thematic mapper/Enhanced Thematic Mapper (TM/ETM) images of the oasis of the middle reaches of the Shulehe River Basin in 1990, 2000, and 2013 were selected to be used as basic data in order to study ecological evolution, and determine the ecological protection target of the oasis of the middle reaches of the Shulehe River Basin in 2020 and 2030. According to different types of eco-environmental water requirements in the oasis of the middle reaches of the Shulehe river basin, a quantification model for such water requirements was established and the current status and protection targets of eco-environmental water requirements were estimated. This would provide reference for the rational allocation of regional water resources and the coordinated development of an ecological system. These results indicate that the eco-environmental water requirements of natural vegetation, basic eco-environmental water requirements, transportation sand eco-environmental water requirements, recharge of watercourse seepage water requirements, water surface evaporation eco-environmental water requirements, marsh eco-environmental water requirements and combating salinization of farmlands eco-environmental water requirements of the oasis of the middle reaches of the Shulehe river basin were 1.90×10⁸, 0.98×10⁸, 1.11×10⁸, 0.83×10⁸, 0.68×10⁸, 2.70×10⁸, 0.20×10⁸, 2.24×10⁸, 0.98×10⁸, 1.11×10⁸, 0.83×10⁸, 0.73×10⁸, 3.13×10⁸, 0.20×10⁸ m³ and 2.47×10⁸, 0.98×10⁸, 1.11×10⁸, 0.83×10⁸, 0.80×10⁸, 3.71×10⁸, 0.20×10⁸ m³ in 2013, 2020 and 2030, respectively. At the same time, the maximum of eco-environmental water requirements, minimum of eco-environmental water requirements, and optimum eco-environmental water requirements of the oasis of the middle reaches of the Shulehe river basin were 7.42×10⁸, 7.09×10⁸, 7.29×10⁸, 8.24×10⁸, 7.91×10⁸, 8.11×10⁸ m³ and 9.12×10⁸, 8.79×10⁸, 8.99×10⁸ m³ in 2013, 2020 and 2030, respectively. The annual variation of eco-environmental water requirement was concentrated mainly from May to August and proportion of cumulative eco-environmental water requirements of the total ecological environment water demand were 58.01%, 58.08% and 58.13% in 2013, 2020 and 2030, respectively. The water requirements of Guazhou County eco-environmental water requirements were relatively greater than those of Yumen City and Dunhuang City. The study results will provide a basis for the management program of Dunhuang water resources reasonable utilization and ecological protection. Additionally, it will be an important source for promoting the research of ecological water rights, allocation of water quantity, and coordinated and sustainable development among ecological protection, reasonable configuration of water resources and economic society in Shulehe river basin. http://www.ecologica.cn