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Drought Assessments and Numerical Models of Groundwater Flow and Contaminant Transport: Applications to Groundwater Management and International Policy
Date
2023-11-30Metadata
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Humanity relied on groundwater for centuries to cover some of its water needs. In 2015 groundwater accounted for 50% of total consumptive water use worldwide, of which 69% was used for irrigation and 18% for public supply. The growing reliance on groundwater use triggers concerns about groundwater depletion, quality threats, and sustainability. This work explains three approaches to address these concerns. First, assessing droughts using satellite products and drought indexes to forecast short-term weather conditions for small regions and apply this method to the Allende-Piedras Negras (APN) aquifer in Mexico-Texas of USA border. My main finding is that winters with temperatures slightly below the annual mean or “mild winters” are predecessors of harsh summers. Second, quantifying available groundwater volumes across political borders by developing the Transboundary Flow Balance Index (TFBI), which targets the critical sectors where groundwater pumping is sufficient to cause groundwater flow direction changes in the neighboring political border areas. I have applied this index to the APN aquifer and find that the TFBI favors the U.S. in the northern sector of the aquifer, and Mexico in the southern sector. I also find that it is not necessary to have high pumping rates to cause the groundwater flows to move across political borders, but land slope is the controlling factor. Third, forecasting the rate of increase in total dissolved solids (TDS) within the Simsboro aquifer, which covers the water needs of the cities of College Station-Bryan; this aquifer is a long-term source of sustainable freshwater, but the water levels in the aquifer are decreasing while the salinity (TDS) increases due to overpumping. modify the numerical model of groundwater flow from the Texas Water Development Board and include transport to forecast the TDS increase rate under three scenarios (projected steady, projected, 10% over the projected demand) until 2100. I find that the actual pumping rates on the Simsboro are unsustainable, and that the TDS will slightly increase under the projected pumping scenario at the Bryan–College Station area. These approaches are useful for developing groundwater strategies that support policymaking, challenges accompanying a growing population, and agriculture development, the region's main economic activity.
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Citation
Rodriguez Lozada, Laura Marcela (2023). Drought Assessments and Numerical Models of Groundwater Flow and Contaminant Transport: Applications to Groundwater Management and International Policy. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /203055.