The Role of Bedrock Groundwater in Rainfall-Runoff Process at Hillslope and Catchment Scales in a Headwater Catchment with Sub-Humid Climate

Abstract:

Recent studies have suggested that bedrock groundwater can exert considerable influence on rainfall-runoff process in headwater catchments. However, study of the role of bedrock groundwater on rainfall-runoff process in a headwater catchment is still challenged due to limited direct observation data of bedrock groundwater. In this study, we aimed at characterize the bedrock groundwater’s response to rainfall at hillslope and catchment scales in a small headwater catchment with semi-humid climate. We selected a headwater catchment of Miyun Reservoir, which is an important drinking water source of Beijing, as study area. The catchment bedrock is mainly consists of fractured granite. Major chemical constituents and stable isotopic compositions (δ¹⁸O, δD) were analyzed roughly monthly from July 2013 to July 2014 for rainwater, spring water and groundwater in the study area and neighboring catchment. Eleven wells with depth ranged from 5 to 26 m were drilled in three slopes to monitor the bedrock water table. Two soil moisture observation locations were arranged in one hillslope, and a weather station was installed to measure soil moisture and rainfall with 10-mintue interval. The recharge mechanism of bedrock groundwater is explored by combined use of hydrometric and hydrochemical approaches.