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Person

Leon J Kauffman

Hydrologist
Email: lkauff@usgs.gov
Office Phone: 406-754-3332

Location
3450 Princeton Pike
Suite 110
Lawrenceville , New Jersey 08648
US
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The Southern Nevada volcanic-rock aquifers reside in southern-central Nevada. This group of aquifers can be categorized into welded tuff, bedded tuff, and lava flow aquifers. Each of these categories possess different physical characteristics and have varying degrees of welding and number of interconnected joints. The lithology of these aquifers is primarily dependent on mode of eruption and cooling and are highly variable. Because the lithology is so variable, so is groundwater transmission, storage, and yield (HA 730-B). This product provides source data for the Southern Nevada volcanic-rock aquifers framework, including: Extent shapefiles: 1. p_57SRNVDV.shp: Polygon shapefile containing the areal extent...
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This dataset provides the estimated number of people using publicly supplied groundwater (PSg) or publicly supplied surface water (PSs) for each county in the conterminous U.S. The county boundaries, the PSg, and the PSs represent the year 2010
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The Ada-Vamoosa aquifer resides in the Central Lowland Physiographic Province in east-central Oklahoma and ends at the Kansas State line. The aquifer underlies an area of about 2,300 square miles. The aquifer consists mainly of layers of fine to coarse-grained sandstone irregularly interbedded with shale and limestone. The rocks are in the Ada and the Vamoosa Groups are Pennsylvanian age. The maximum thickness of the aquifer is about 900 feet. The aquifer is productive where conditions are unconfined and acts as the primary water source for several towns in the area (HA 730-E). This product provides source data for the Ada-Vamoosa aquifer framework, including: Georeferenced images: 1. i_28ADAVMS_top.tif: Digitized...
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Groundwater age is an important indicator of groundwater susceptibility to anthropogenic contamination and a key input to statistical models for forecasting water quality. Numerical models can provide estimates of groundwater age, enabling interpretation of measured age tracers. However, to extend to national-scale groundwater systems where numerical models are not routinely available, a more efficient metamodeling approach can provide a less precise but widely applicable estimate of groundwater age, trained to make forecasts based on predictor variables that can be measured independent of numerical models. We trained gradient-boosted regression tree statistical metamodels to MODFLOW/MODPATH derived groundwater...
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A boosted regression tree (BRT) model was developed to predict pH conditions in three-dimensions throughout the glacial aquifer system (GLAC) of the contiguous United States using pH measurements in samples from 18,258 wells and predictor variables that represent aspects of the hydrogeologic setting. Model results indicate that the carbonate content of soils and aquifer materials strongly controls pH and when coupled with long flow paths, results in the most alkaline conditions. Conversely, in areas where glacial sediments are thin and carbonate-poor, pH conditions remain acidic. At depths typical of drinking-water supplies, predicted pH > 7.5 – which is associated with arsenic mobilization – occurs more frequently...
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