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Anomalous behavior of soil mantle groundwater demonstrates the major effects of bedrock groundwater on surface hydrological processes
Author(s) -
Kosugi Ken'ichirou,
Katsura Shin'ya,
Mizuyama Takahisa,
Okunaka Suemi,
Mizutani Tasuku
Publication year - 2008
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2006wr005859
Subject(s) - groundwater , bedrock , hydrology (agriculture) , groundwater flow , geology , perennial stream , groundwater discharge , hydrogeology , groundwater recharge , groundwater model , landslide , surface water , environmental science , aquifer , geomorphology , geotechnical engineering , computer network , streams , computer science , environmental engineering
The formation of groundwater in the soil mantle has a dominant effect on rainwater discharge and shallow landslide occurrence in headwater catchments. Here, we report two completely different groundwater responses within a single well excavated into the soil mantle. One was an ephemeral‐type response that is well described by physical hydrology models based on a geographic information system (GIS). The other was a semi‐perennial‐type response, rarely reported in previous studies, which cannot be explained by the existing physical models. The semi‐perennial groundwater caused considerably high antecedent groundwater tables between storms, leading to an increased peak in the groundwater level during later heavy storm events and a likely increase in the risk of shallow landslides. Moreover, peaks in the semi‐perennial groundwater lagged considerably behind rainstorm events, which probably affected base flow discharge by forming a delayed peak. Geochemical and geothermal observations indicated that the source of the semi‐perennial groundwater was deep bedrock groundwater, demonstrating the considerable effects of bedrock groundwater on surface hydrological processes.