WATER RESOURCES RESEARCH GRANT PROPOSAL
Project ID: 2004WA76B
Title: Three-dimensional Characterization of Riverbed Hydraulic Conductivity and Its Relation to Salmonid Habitat Quality
Project Type: Research
Focus Categories: Ecology, Surface Water, Groundwater
Keywords: Salmonid, Habitat Quality, Touchet River, Hydraulic Conductivity, Slug Test, Geostatistical Analysis, MODFLOW
Start Date: 03/01/2004
End Date: 02/28/2005
Federal Funds: $24,000
Non-Federal Matching Funds: $48,147
Congressional District: Washington, 5th
Timothy P. Hanrahan
Pacific Northwest National Laboratory
The health and viability of fish stocks in the Pacific Northwest have long been a critical issue. The recent listing of salmon species as threatened or endangered by the National Marine Fisheries Service signifies the urgent need for fish habitat protection and restoration. Studies have overwhelmingly indicated the degradation of natural salmon habitat due to excess sedimentation from agricultural lands. Many streams and rivers in the Pacific Northwest have been included on the 303(d) list for sedimentation. It is well established that the hydraulic properties of the riverbed can directly affect salmon habitat quality. The spatial variability of saturated hydraulic conductivity plays a major role in subsurface water flow and solute transport. Yet in most hydrological studies, the streambed is commonly represented as a layer of uniform thickness and low permeability.
We propose to develop a three-dimensional characterization of the riverbed hydraulic conductivity in a selected representative reach of the Touchet River in the dryland agricultural area of the Pacific Northwest, and to relate this hydraulic property to habitat quality. The specific objectives are: (1) to conduct a detailed field measurement of the three-dimensional distribution of hydraulic conductivity under the riverbed surface using slug tests; and (2) to perform statistical and spacial analyses of the field-measured hydraulic conductivity and the derived specific discharge data as well as their relationship to salmon habitat quality. The primary product of this study will be a complete, three-dimensional characterization of riverbed hydraulic conductivity in a Pacific Northwest stream. Such characterization contributes to a better understanding of the natural heterogeneity of the riverbed and surface water and ground water interactions in this region. The secondary product of the study is the evaluation of salmon habitat quality in a dryland reach typically found in the Touchet River watershed in the Lower Columbia River Basin. This research serves as pilot study which uses detailed field measurements of riverbed hydraulic conductivity to evaluate salmon habitat quality.