The accurate knowledge of water and chemical mass balances is the key to proper management of water resources in a watershed. After decades of field investigations and modeling, groundwater storage, fluxes between surface and subsurface reservoirs, and fluxes between land surface and atmosphere over a basin/watershed still remain highly uncertain. A breakthrough in characterization, monitoring, and modeling approaches is needed to resolve this issue. In this proposal, we propose a novel hydraulic tomography approach to characterize, monitor, and predict the hyporheic zone and beyond, using spatial-temporal variations in river stages and the corresponding groundwater responses near a river. This new technology allows three-dimensional imaging and determination of fluxes across the river/groundwater boundaries and characterization of the hyporheic and subsurface system in a manner that is presently not feasible. If this proposed proof-of-concept study is successful, the technology can ultimately be extended to basin/watershed scale problems. The goal of the study is to demonstrate that hydraulic tomography based on river stage fluctuations is a valid concept and a viable technology for detecting large-scale subsurface heterogeneity near the river. We intend to show that the concept and technology can accomplish its goal in unconfined aquifers that interact with rivers. Proposed tasks include: 1) the modification of existing hydrologic tomography inversion algorithm to accommodate temporally and spatially varying boundary conditions, which represent the temporally and spatially varying river stages; 2) the examination of the effects of temporal and spatial varying river stage on groundwater level in synthetic heterogeneous unconfined aquifers through numerical simulations; 3) the use of these simulated well hydrographs in the modified inversion algorithms to test its ability to detect heterogeneity within the hyporheic zone; and 4) the conduct of laboratory studies using two existing sandboxes with a synthetic heterogeneous unconfined aquifer. Results from the study should demonstrate that while river stages may change rapidly in time and space, the tomographic inversion is a valid and logical approach as long as the variation of the river stages is well characterized.

Agency
National Science Foundation (NSF)
Institute
Division of Earth Sciences (EAR)
Type
Standard Grant (Standard)
Application #
0450388
Program Officer
L. Douglas James
Project Start
Project End
Budget Start
2005-05-15
Budget End
2007-04-30
Support Year
Fiscal Year
2004
Total Cost
$62,500
Indirect Cost
Name
University of Arizona
Department
Type
DUNS #
City
Tucson
State
AZ
Country
United States
Zip Code
85721