State-of-the-art Geophysical and Ground Water Salinity Logging Applied in Numerical Analysis of Water Quality in Wetland-Ground Water Systems
* How reliable are cone penetrometer and dynamic borehole logging methods for estimating the depth distribution of salts in a ground water aquifer under seasonally flooded wetlands?
* Can a field methodology be developed using a combination of these techniques to map the subsurface water quality for the purpose of ground water conjunctive use assessment and planning?
Need and Benefit
The ground water aquifers beneath seasonally flooded wetlands are being evaluated by Reclamation for possible ground water conjunctive use to meet Level IV refuge water supply obligations mandated by the Central Valley Project Improvement Act (CVPIA). In the San Joaquin Basin, the Grassland Water District and the San Luis National Wildlife Refuge receive water supply from the Delta Mendota Canal; the same system that delivers water to Reclamation's agricultural customers. These increased water supply requirements under CVPIA, when combined with pumping export restrictions at the Tracy pumps, have made exploration of ground water conjunctive use a high priority for the water acquisition program.
Four factors will be considered in future evaluation of ground water conjunctive use options:
* Potential yield from existing or newly installed pumping wells
* Short and long-term salinity of water extracted from pumped wells
* Impact of potential pumping on local and regional ground water levels and quality
* Long-term sustainability of a conjunctive use program
The most significant obstacle to assessment of ground water conjunctive use potential is inadequate data on the depth distribution of salts in the regional aquifer. A more thorough inventory and mapping of the depth distribution of salts is needed to develop sustainability estimates. This project will develop a field protocol and test the reliability of two state-of-the-art geophysical logging techniques that in combination could provide Reclamation with the data needed to perform vital project planning leading to increased water supply reliability for the Central Valley Project.
Contact the Principal Investigator for information about these documents.