AN ABSTRACT OF THE DISSERTATION OF Tracy Arras for the degree of Doctor of Philosophy in Water Resources Engineering presented on March 27, 2014. Title: A GIS Approach to Estimating Continuous Hydraulic Conductivity and Equivalent

approved: ______________________________________________________ Jonathan Istok Estimating the hydraulic conductivity of earth materials is important for many water resource modeling efforts, including predicting the transport of pollutants in ground water, computing surface runoff for flood control, and computing water budgets. This research implicitly used topography, soil, and climate data to estimate plausible continuous hydraulic conductivity values at a basin-wide scale. The study demonstrated that continuous estimates of aquifer hydraulic conductivity using a geographic information system (GIS) approach are plausible. Manuscript 1 investigated the effects of different GIS stream generation methods on continuous estimates of conductivity and independent sources were used to verify the plausibility of the results ranging from well pumping tests to Soil Survey Geographic Database (SSURGO). Because of the disparity between the scales at which measurements are taken for traditional conductivity estimates and those required for hydraulic and hydrologic modeling, conductivity point data are typically upscaled to the meter-to-kilometer scale and then referred to as equivalent conductivities. Manuscript 2 developed and tested a new method for computing basin-scale equivalent hydraulic conductivities and explored the relationships of catchment and drainage paths equivalent conductivities to a watershed’s equivalent conductivity using GIS. Manuscript 3 investigated how the methodology of using GIS and landscape descriptors to estimate continuous hydraulic conductivity and equivalent conductivity are impacted by DEM resolution.