Examples of deformation-dependent flow simulations of conjunctive use with MF-OWHM
Other literature type
Hanson, R. T.
Boyce, S. E.
Hughes, J. D.
The dependency of surface- and groundwater flows and aquifer
hydraulic properties on deformation induced by changes in aquifer head is
not accounted for in the standard version of MODFLOW. A new USGS integrated
hydrologic model, MODFLOW-OWHM, incorporates this dependency by linking
subsidence and mesh deformation with changes in aquifer transmissivity and
storage coefficient, and with flows that also depend on aquifer
characteristics and land-surface geometry. This new deformation-dependent
approach is being used for the further development of the integrated Central
Valley hydrologic model (CVHM) in California. Preliminary results from this
application and from hypothetical test cases of similar systems show that
changes in canal flows, stream seepage, and evapotranspiration from
groundwater (ET<sub>gw</sub>) are sensitive to deformation. Deformation feedback
has been shown to also have an indirect effect on conjunctive surface- and
groundwater use components with increased stream seepage and streamflows
influencing surface-water deliveries and return flows. In the Central Valley
model, land subsidence may significantly degrade the ability of the major
canals to deliver surface water from the Delta to the San Joaquin and Tulare
basins. Subsidence can also affect irrigation demand and ET<sub>gw</sub>, which,
along with altered surface-water supplies, causes a feedback response
resulting in changed estimates of groundwater pumping for irrigation. This
modeling feature also may improve the impact assessment of
dewatering-induced land subsidence/uplift (following irrigation pumping or
coal-seam gas extraction) on surface receptors, inter-basin transfers, and
surface infrastructure integrity.