Change of the relationship between recharge, runoff and drainage of groundwater in Tianqiao spring region and Yellow River reach and its impact on runoff

Since 1973, the observed runoff of the uncontrolled areas of the section between Hekouzhen and Wubao of the Yellow River has remarkably decreased, or even, it had been dried up for a quarter of the years; based on the rainfall- runoff relationship between 1956 to 1972, the observed runoff decreased by 84% under the rainfall condition from 1973 to 2014. In this paper, the analysis results showed that the relationship between recharge, runoff and drainage of groundwater and in the Tianqiao spring region of the Yellow River has changed because of reservoir operation along the main stream of this section. This not only significantly reduced the spring recharge into the Yellow River on the left bank, but also increased the amount of leakage to the karst aquifer on the right bank. It is the main reason for the remarkable observed runoff reduction of the uncontrolled areas of section between Hekouzhen and Wubao of the Yellow River. In comparison of rainfall- runoff relationships in different periods, and analysis of water reducing effect of other underlying factors, such as vegetation, terraces and surface water evaporation of dams, the calculation results showed that changes of the recharge relationship between spring water and runoff resulted in runoff reduction of about 600-800 million m3 per year on average in the Yellow River. © 2016, Science Press. All right reserved.