Quantifying impacts of climate variability and human activities on the hydrological system of the Haihe River Basin, China

In the last 50 years, the hydrological system of the Haihe River Basin in northern China has undergone great changes, such as declines in runoff and discharge, rivers drying up, and groundwater depletion. Both climate variability and human activities have been regarded as causes for these changes, but which is the major reason was not clear in the past. This paper aims to quantify the impact of climate variability, particularly changes of precipitation, and human activities (water storage projects, agricultural development, soil and water conservation projects, and agricultural water saving) on the hydrological system of the basin. A basin-level water consumption balance model was used to simulate the changes of the hydrological system during the period of 1958–2008. The non-parametric Mann–Kendall test and Pettitt’s test methods were adopted to identify trends and change points of the hydrological factors. And the contribution of climatic variability and human activities was calculated based on the multi-year average of all the climatic and hydrological parameters of different river basin management stages and their relative changes between adjacent periods. The results show that from 1958 to 1965 the basin hydrological system was in the natural state of equilibrium. During 1966–1978 human activities were the main factors with the contribution of 96.1 and 76.6 % for the upstream and downstream area. During the period of 1979–1988, the change of precipitation was the main factor to cause the upstream and downstream hydrological system changes with contributions of 73.8 and 64.1 %. In the period of 1989–2000 and 2001–2008, the climate variability still dominated the impact of the hydrological system changes in the upstream and downstream areas. Based on these findings, some measures were recommended to improve the balance of the hydrological system in this basin including recharging the downstream area with water that is currently stored in the upstream, implementing agricultural water-saving practices in the basin, and using treated sewage from the cities for river environmental flow recovery and wetland restoration.