地质科技通报 (Mar 2024)
Recharge coefficients and recharge mechanisms of precipitation to groundwater in karst areas of North China: A case study of Yangzhuang karst water system
Abstract
Objective To establish a series of hydrogeological parameter for karst areas in North China, an on-site experimental study on water balance has been carried out since the 1980s in a closed spring-drainage karst water system in Yangzhuang, Shandong Province. Methods Based on long-term field observations of water balance elements spanning more than 40 years, the formulas for calculating precipitation infiltration recharge coefficients in bare, semi-covered and covered karst areas were derived. The correlation equations of the precipitation infiltration recharge coefficient α with precipitation P and water table depth D, as well as the series of adjustable maximum precipitation infiltration recharge coefficients in karst areas, were also established. The processes of precipitation infiltration and recharge and the mechanism of α change were explored. Results The results showed that α varied with D. Each rainfall segment P corresponded to a maximum precipitation infiltration recharge coefficient αmax and a maximum precipitation infiltration recharge volume, namely, the recharge limit Gmax, while the corresponding depth of water table was the optimal depth of water table Dcritical. When D was greater than Dcritical, the interception of the vadose zone increased with increasing water table depth and α was less than αmax.When D was less than Dcritical, the surface runoff increased with decreasing water table depth and α was less than αmax. Different rainfall segments corresponded to different Dcritical, and the corresponding αmax and Dcritical increased with increasing precipitation. At any water table depth, Gmax was constant and equal to the difference between the critical rainfall of saturation excess runoff and the maximum interception volume of vadose zone. Conclusion This study addressed the key scientific issues related to precipitation infiltration recharge in karst areas and improved the research level of karst water resources in North China.
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