干旱区生态环境知识资源中心

Owing to the shortage and the irrational utilization of water resources in the Heihe River, the eco-environment has deteriorated seriously in its lower reaches. Some ecological problems exist, i.e., lake shrinkage, the decline of the underground water table, vegetation degradation, land desertification and sandstorm damage, threatening the ecological security of the region. Remote sensing images on the Arc GIS platform are adopted to analyze the evolution trend of the vegetation landscape pattern in the lower reaches of the Heihe River. The results show that the extent of desertification is far greater than the strength of the oasis process. Ecological restoration and protection is imperative. Using a comprehensive decision-making method and GIS technology, considering the course of the river, its ecosystem characteristics and the range of impact of water resource allocation, targets of ecological protection in the lower reaches of the river are proposed. According to the phreatic evapotranspiration model and the groundwater balance equation, the ecological water requirements of the riparian forest ecosystem, the desert ecosystem, the water area ecosystem and the underground ecosystem, given various eco-restoration targets in different level years, were calculated. The spatial and temporal variation of the ecological water requirements were analyzed, which provides a scientific basis for reasonable water resources allocation.