From Bureau of Economic Geology, The
University of Texas at Austin (www.beg.utexas.edu).
For more information, please contact the author.
Bureau Seminar, December 4, 2009
Climate Change and Land Use Change Impacts on
Groundwater Resources in Semiarid Regions
Link to streaming video: available 12.04.2009 at 8:25am
Bureau of Economic Geology
What impact will climate variability/change (e.g., El Nino Southern Oscillation, future climate change) and land use change (e.g., crop and biofuel production and terrestrial carbon sequestration) have on already scarce groundwater resources in semiarid regions? By changing partitioning of water among evapotranspiration (ET), runoff, and recharge, climate and land use can exert large-scale impacts on groundwater resources. In our study, we measured the impacts of climate and land use on groundwater resources using satellite (GRACE, MODIS, Landsat) data, land surface monitoring (ET using large aperture scintillometers), and subsurface unsaturated zone profiling and groundwater hydrographs and quality. Soil physics, environmental tracers, and groundwater hydrographs and quality provide archives of past impacts of climate and land use on groundwater recharge. Case studies on impacts of climate change and land use change will be presented for various semiarid regions, including High Plains, US; Niger, West Africa; Rajasthan, India; Murray Darling Basin, SE Australia; and Argentina, S. America. Results show that Pleistocene/Holocene climate change and associated reduction in precipitation greatly decreased groundwater recharge and accumulated salts in unsaturated media. Conversion of natural ecosystems to rain-fed agroecosystems increased recharge and mobilized salt reservoirs in semiarid regions globally. Irrigation greatly depletes groundwater resources, while simultaneously accumulating salts and nutrients. Simulations of impacts of future climate on groundwater recharge in the High Plains suggest that both variations in annual precipitation and precipitation intensity impact episodic recharge in the region. Both climate and land use markedly alter partitioning of water at the land surface and groundwater recharge. An examination of links between land use and groundwater recharge suggests that land use may be used as a parameter to manage water resources in the future.