Ecological risk assessment in the Ziya watershed under the influences of land use change and water resource shortage

Over the past few decades, the ecological risk in the Ziya watershed has increased due to rapid economic growth, population expansion, and water resource overexploitation. Therefore, a typical index system for comprehensive ecological risk assessment at the grid scale was constructed under the influences of land use change and water resource shortage. As an essential element for describing droughts and water shortages, the ecological water shortage quota was introduced into the index system. Then, the significant influencing factors of ecological risk change were identified. The results showed that farmland consistently experienced precipitation deficits. In regard to natural vegetation, precipitation in the watershed could not sustain normal growth. Therefore, vegetation water shortages should be considered in risk assessment. Furthermore, the ecological risk showed an increasing tendency from 1990 to 2018, which was dominated by moderate- and middle-high-risk zones. The high-risk areas were primarily located in the plain area of Hebei Province and northeastern part of Shanxi Province, while the low-risk areas were located in the northwestern part of the watershed. Water resource shortages and land use changes are important factors influencing the ecological risk. Based on a county-scale risk source-habitat-risk receptor framework, four ecological risk zones were established, and the major problems in each zone were identified. The results could provide a reference for optimal allocation of agricultural water resources in the Ziya watershed.