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Potential contribution of topography‐driven regional groundwater flow to fractal stream chemistry: Residence time distribution analysis of Tóth flow
Author(s) -
Cardenas M. Bayani
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl029126
Subject(s) - groundwater , aquifer , residence time (fluid dynamics) , flow (mathematics) , fractal , groundwater flow , streams , geology , hydrology (agriculture) , fractal analysis , residence time distribution , subsurface flow , soil science , environmental science , fractal dimension , mechanics , geotechnical engineering , mathematics , physics , mathematical analysis , computer network , computer science
Groundwater and surface water are interconnected. Tóth's analysis of topography‐driven groundwater flow, presumably exiting in lakes or streams, is one of the first illustrations of this connection. Recently, fractal behavior in time‐series observations of stream chemistry, implying a power‐law residence time distribution (PLRTD) has been attributed to heterogeneity in subsurface flow paths and mass exchange processes. We show through numerical simulations that topography‐driven groundwater flow, i.e., Tóth flow, and transport under homogeneous aquifer conditions results in PLRTDs and may therefore contribute to fractal behavior in surface water chemistry. For the first time, PLRTDs are explained with a purely physical basis. Heterogeneity, accounted for by a large dispersivity value, makes the PLRTD more pronounced and persistent. Late‐time arrival of solutes from surrounding watersheds results in multi‐modality in the RTD, but these late peaks also follow a PLRTD after arrival.