The Columbia Plateau Groundwater Availability (CPLAT) study began in October 2007 and will end in 2012. The major elements of the approach include:
- Documenting changes in the status of the system. We will compile data from existing groundwater level monitoring networks maintained by a variety of agencies in the study area. We will collect additional data in areas not covered by existing networks. The goal will be to characterize the current status of groundwater levels and compare with the status in 1984 when the last regional scale compilation was made as part of the USGS Regional Aquifer System Analysis (RASA).
- Quantifying the hydrologic budget for the system. We will use a variety of hydrologic data and models to quantify the major components of the hydrologic budget for the aquifer system. The primary components of recharge include infiltration of precipitation and snowmelt and irrigation return flow. The primary components of discharge include groundwater pumping and discharge to streams.
- Updating the regional geologic framework for the basalt and basin-fill aquifers. The RASA study mapped the extent and thickness of the major basalt formations and basin-fill sediments. We will compile and evaluate new geologic mapping and subsurface information and use it to refine the regional framework. The refined framework will be compiled in a three-dimensional spatial database.
- Developing a groundwater flow simulation model for the system. A conceptual model of the system based on the results of elements 1-3 will be used to construct a three-dimensional numerical simulation model. The simulation model will be used to evaluate and test the conceptual model and later to evaluate groundwater availability under alternative development and climate scenarios.
