Impact Assessment of Climate Change and Human Activities on Runoff Variation in Coal Mining Watershed, NW China

Resumo

The Kuye river watershed is a coal mining watershed in Northwest China. The study analyzed runoff change of year, high flow period and low flow period in the past 60 years based on Mann-Kendall trend test, cumulative anomaly, and continuous wavelet analysis. The contributions of climate change and human activities on runoff variation were assessed by the rainfall-runoff relationship model. The results were obtained: (1) Runoff in year, high and low flow period showed a significant declining trend during 1954–2015, but the trends of decreasing or increasing of precipitation and evaporation were not notable. (2) Runoff in year, highflow period and low flow period exhibited similar abrupt change feature and stage characteristic. (3) The periodic changing characteristics of runoff in high flow period were similar to those in annual runoff, but those in low flow period were different from annual runoff. (4) The effect of climate change on runoff had an significant decreasing trend from 61.73 to 9.19% in year, from 59.76 to 2.68% in high flow period, and from 25.00 to 2.63% in low flow period. Compared with climate change, the impact of human activities increased obviously, the contribution all over 90.00% in 1997–2015. Thus, human activities demonstrated the dominant influence on runoff decline gradually.