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A numerical investigation of bedrock groundwater recharge and exfiltration on soil mantled hillslopes
Author(s) -
Gardner W. Payton,
Jensco Kelsey,
Hoylman Zachary,
Livesay Robert,
Maneta Marco
Publication year - 2020
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.13799
Subject(s) - groundwater recharge , bedrock , geology , groundwater , hydrology (agriculture) , groundwater model , groundwater flow , hydraulic conductivity , vadose zone , subsurface flow , infiltration (hvac) , groundwater discharge , soil water , geomorphology , soil science , aquifer , geotechnical engineering , physics , thermodynamics
Here we use Richards Equation models of variably saturated soil and bedrock groundwater flow to investigate first‐order patterns of the coupling between soil and bedrock flow systems. We utilize a Monte Carlo sensitivity analysis to identify important hillslope parameters controlling bedrock recharge and then model the transient response of bedrock and soil flow to seasonal precipitation. Our results suggest that hillslopes can be divided into three conceptual zones of groundwater interaction, (a) the zone of lateral unsaturated soil moisture accumulation (upper portion of hillslope), (b) the zone of soil saturation and bedrock recharge (middle of hillslope) and (c) the zone of saturated‐soil lateral flow and bedrock groundwater exfiltration (bottom of hillslope). Zones of groundwater interaction expand upslope during periods of precipitation and drain downslope during dry periods. The amount of water partitioned to the bedrock groundwater system a can be predicted by the ratio of bedrock to soil saturated hydraulic conductivity across a variety of hillslope configurations. Our modelled processes are qualitatively consistent with observations of shallow subsurface saturation and groundwater fluctuation on hillslopes studied in our two experimental watersheds and support a conceptual model of tightly coupled shallow and deep subsurface circulation where groundwater recharge and discharge continuously stores and releases water from longer residence time storage.