Thesis
The effects on groundwater resources from irrigation supply changes in the Odessa subarea of the Columbia Plateau aquifer.
Washington State University
Master of Science (MS), Washington State University
2022
DOI:
https://doi.org/10.7273/000005158
Abstract
Global population growth is driving the need for crop production expansion to meet increasing food supply demands. To support this crop production, both surface and groundwater are used for irrigation. However, reliance on groundwater has been significantly increasing in recent decades due to changes in demand as well as surface water availability and/or reliability. As a consequence, groundwater declines have been observed worldwide where irrigation is the leading cause. In this study, spatial and temporal changes in hydraulic head are evaluated in response to the Odessa Groundwater Replacement Program (OGWRP). The Odessa Subarea is a region in the Columbia Plateau Regional Aquifer System (CPRAS) of the Pacific Northwest that has been experiencing severe groundwater declines due to irrigation pumping since the 1960s. The OGWRP will replace groundwater rights with surface water rights in an attempt to stabilize the water levels in the deep basalts from which the majority of irrigation water is pumped. Numerical flow models assist in estimates of groundwater availability in a study area and the evaluation of water level trends. Using an existing CPRAS model developed by the U.S. Geological Survey (USGS), the composite hydraulic heads resulting from systematic pumping changes in wells found within the Odessa Subarea were simulated. This work tested the hypothesis that aquifer recovery is feasible in response to OGWRP implementation. The study results showed that irrigation supply changes in Odessa impact beyond its boundary. The Grande Ronde Basalt, which supplies most of irrigation water demands in Odessa, has the greatest potential to recover of up to 49.8% by 2050 to predevelopment state if groundwater pumping stopped in 2008. Moreover, the study found two main limitations of the model related to uncertainties in commingling flow and recharge mechanisms in the deep aquifers. Without improved knowledge of recharge pathways and controls and timescales of the intra-borehole flows that are induced in uncased wells, it is difficult to quantify the overall model performance. To reduce model uncertainty the calibration of commingling wells is suggested.
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Details
- Title
- The effects on groundwater resources from irrigation supply changes in the Odessa subarea of the Columbia Plateau aquifer.
- Creators
- Nyamaa Mendsaikhan
- Contributors
- Alexandra Richey McLarty (Advisor)Timothy Rollins Ginn (Committee Member)Nicholas B Engdahl (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 94
- Identifiers
- 99901019939801842
- Language
- English
- Resource Type
- Thesis