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A method for estimating spatially variable seepage and hydraulic conductivity in channels with very mild slopes
Author(s) -
Shanafield Margaret,
Niswonger Richard G.,
Prudic David E.,
Pohll Greg,
Susfalk Richard,
Panday Sorab
Publication year - 2012
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.9545
Subject(s) - thalweg , hydraulic conductivity , infiltration (hvac) , geology , ephemeral key , hydrology (agriculture) , groundwater , groundwater recharge , modflow , groundwater model , channel (broadcasting) , spatial variability , streams , groundwater flow , streamflow , soil science , geotechnical engineering , geomorphology , aquifer , sediment , soil water , mathematics , algorithm , computer network , computer science , engineering , thermodynamics , statistics , physics , electrical engineering , geography , drainage basin , cartography
Infiltration along ephemeral channels plays an important role in groundwater recharge in arid regions. A model is presented for estimating spatial variability of seepage due to streambed heterogeneity along channels based on measurements of streamflow‐front velocities in initially dry channels. The diffusion‐wave approximation to the Saint‐Venant equations, coupled with Philip's equation for infiltration, is connected to the groundwater model MODFLOW and is calibrated by adjusting the saturated hydraulic conductivity of the channel bed. The model is applied to portions of two large water delivery canals, which serve as proxies for natural ephemeral streams. Estimated seepage rates compare well with previously published values. Possible sources of error stem from uncertainty in Manning's roughness coefficients, soil hydraulic properties and channel geometry. Model performance would be most improved through more frequent longitudinal estimates of channel geometry and thalweg elevation, and with measurements of stream stage over time to constrain wave timing and shape. This model is a potentially valuable tool for estimating spatial variability in longitudinal seepage along intermittent and ephemeral channels over a wide range of bed slopes and the influence of seepage rates on groundwater levels. Copyright © 2012 John Wiley & Sons, Ltd.