Groundwater depletion is an important problem driven by population growth, land use and land cover (LULC) change, climate change, and other factors. Groundwater depletion generates water stress and encourages unstainable resource use. The aim of this study is to determine how population growth, LULC change, and climate change relate to groundwater depletion in the Alto Atoyac sub-basin, Oaxaca, Mexico. Twenty-five years of dry season water table data from 1984 to 2009 are analyzed to examine annual groundwater depletion. Kriging is used to interpolate the region’s groundwater levels in a geographic information system (GIS) from mapped point measurements. An analysis of remotely sensed data revealed patterns of LULC change during a 34-year (1986–2018) period, using a supervised, machine-learning classification algorithm to calculate the changes in LULC. This analysis is shown to have an 85% accuracy. A global circulation model (GFDL-CM3) and the RCP4.5 and RCP8.5 scenarios were used to estimate the effects of climate change on the region’s groundwater. Estimates of evapotranspiration (using HELP3.5 code) and runoff (USDA-SCS-CN), were calculated. Since 1984, the region’s mean annual temperature has increased 1.79 °C and urban areas have increased at a rate of 2.3 km2/year. Population growth has increased water consumption by 97.93 × 106 m3/year. The volume of groundwater is shrinking at a rate of 284.34 × 106 m3/year, reflecting the extreme pressure on groundwater supply in the region. This research reveals the nature of the direct impacts that climate change, changing LULCs, and population growth have in the process of groundwater depletion.
This study analyzes effects of climate change (CCh) and of the increase of impervious surfaces on the groundwater recharge in the Alto Atoyac sub-basin (Oaxaca, southern Mexico). Water recharge was modeled based on HELP 3.95D; temperature and precipitation were derived, for a near (2015–2039) and a far distant future scenario, from GFDL-CM3 global circulation model (GCM), which describes the climate of Mexico under the RCP8.5 scenario. Potential recharge loss zones for the period of 1979–2013 were estimated through a remote sensing analysis. The actual estimated mean annual recharge of 169 million cubic metres could be reduced by 17.97% and 65.09% according to the analyzed CCh scenarios, and the loss of 135 km2 of permeable soil would represent additionally 2.65 × 106 m3 of non-infiltrated water. This study indicates three sites, with high recharge potential, and it can be used to propose local adaptations to guarantee the availability of the water resource in the studied sub-basin.
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