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Role of subsurface flow in generating surface runoff: 1. Base flow contributions to channel flow
Author(s) -
Freeze R. Allan
Publication year - 1972
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/wr008i003p00609
Subject(s) - base flow , subsurface flow , antecedent moisture , flow (mathematics) , watershed , hydrograph , surface runoff , hydrogeology , hydrology (agriculture) , geology , channel (broadcasting) , groundwater recharge , environmental science , mechanics , soil science , drainage basin , geotechnical engineering , groundwater , runoff curve number , computer science , aquifer , geography , ecology , physics , cartography , biology , computer network , machine learning
The importance of the subsurface response of watersheds has been vastly underrated in most studies of watershed behavior, both in a quantitative sense and in a generic sense. The mechanism of base flow generation and the nature of watershed response in base flow dominant streams are examined with a deterministic mathematical model that couples three‐dimensional, transient, saturated‐unsaturated subsurface flow and one‐dimensional, gradually varied, unsteady channel flow. The channel flow model uses the single step Lax‐Wendroff explicit technique to solve numerically the full shallow water equations. The subsurface flow model uses the line successive overrelaxation technique to solve numerically the Jacob‐Richards diffusion equation. The results of the simulations on a hypothetical basin suggest a wide variability in watershed response under the influence of variations in rainfall properties, antecedent moisture conditions, and saturated and unsaturated subsurface hydrogeologic properties. This evidence for a wide range of watershed response functions leads to the development of a healthy skepticism toward black box rainfall‐runoff correlations, the concept of basin linearity, and the rationality of hydrograph separation.