Sustainable effect of coal mining on hydrological drought risk: a case study on Kuye river basin, China

Coal mining seriously damages the ecological environment of coal mining area, one of which is the aggravation of hydrological drought risk. To reveal the impact of coal mining on hydrological drought risk, we study the Kuye river basin, a tributary of the Yellow River in China, which has monthly precipitation data from 1950 to 2005 and monthly runoff data from 1954 to 2005. Firstly, the variation point diagnosis method based on information entropy was used to classify the annual runoff change, and then, the Copula coupling function was used to measure the hydrological and drought risks before and after coal mining and then to analyze the impact of coal mining on the hydrological and drought risks of Kuye river basin. The results show that 1980 is the detected variation point, according to which two stages before (1954–1979) and after (1980–2005) coal mining influence can be divided, in which a total of 28 drought events occurred in the former stage, and 31 drought events occurred in the latter stage. The maximum drought severity in the recurrence period of high-risk 100a has increased from 36.5 mm in the natural stage to 145.1 mm in the former human activities stage, and the maximum drought duration has increased from 10.5 months in the latter natural stage to 42.3 months in the human activities stage. Meanwhile, the maximum drought severity in the recurrence period of low-risk 5a increased from 10.2 to 24.8 mm, and the maximum drought duration increased from 3.7 to 10.1 months. The influence of coal mining on the extreme hydrological drought risk in Kuye river basin is significantly greater than that of ordinary hydrological drought risk. The results of hydrological drought risk comparison before and after coal mining can be used to guide the formulation of local coal mining and drought prevention policies and promote the sustainable development of regional economy.