Publications

Streamflows, springs, and wetlands are important natural and cultural resources to the Caddo Nation. Consequently, the Caddo Nation is concerned about the vulnerability of the Rush Springs aquifer to overdrafting and whether the aquifer will continue to be a viable source of water to tribal members and other local residents in the future. Interest in the long-term viability of local...

Coal-tar-based sealcoat, used extensively on parking lots and driveways in North America, is a potent source of PAHs. We investigated how concentrations and assemblages of PAHs and azaarenes in runoff from pavement newly sealed with coal-tar-based (CT) or asphalt-based (AS) sealcoat changed over time. Samples of simulated runoff were collected from pavement 5 h to 111 d following...

Recent studies have concluded that coal-tar-based pavement sealants are a major source of polycyclic aromatic hydrocarbons (PAHs) in urban settings in large parts of the United States. In 2006, Austin, TX, became the first jurisdiction in the U.S. to ban the use of coal-tar sealants. We evaluated the effect of Austin’s ban by analyzing PAHs in sediment cores and bottom-sediment samples...

Karst aquifers occur in a range of climatic and geologic settings. Nonetheless, they are commonly characterized by their vulnerability to water-quality impairment. Two karst aquifers, the Edwards aquifer in south-central Texas and the Upper Floridan aquifer in western Florida, were investigated to assess factors that control the movement of contaminants to public-supply wells (PSWs). The

During 2011–13, the U.S. Geological Survey, in cooperation with the San Antonio River Authority and the Guadalupe-Blanco River Authority, analyzed surface-water and streambed-sediment samples collected from 10 sites in the San Antonio River Basin to provide data for a broad range of constituents that might be associated with hydraulic fracturing and the produced waters that are a...

San Antonio and surrounding municipalities in Bexar County, Texas, are in a rapidly urbanizing region in the San Antonio River Basin. The U.S. Geological Survey, in cooperation with the San Antonio River Authority and the Texas Water Development Board, compiled historical sediment data collected between 1996 and 2004 and collected suspended-sediment and bedload samples over a range of...

In 2014, the U.S. Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) is assessing stream quality across the Piedmont and southern Appalachian Mountains in the southeastern United States. The goal of the Southeast Stream Quality Assessment (SESQA) is to characterize multiple water-quality factors that are stressors to aquatic life—contaminants, nutrients, sediment...

In 2013, the U.S. Geological Survey (USGS) operated more than 500 continuous streamgages (streamflow-gaging stations) in Texas. In cooperation with the Texas Water Development Board, the USGS evaluated mean annual streamflow data for 38 selected streamgages that were active as of water year 2012. The 38 streamgages have annual mean streamflow data considered natural and unregulated...

The Edwards-Trinity aquifer is a vital groundwater resource for agricultural, industrial, and public supply uses in the Pecos County region of western Texas. The U.S. Geological Survey completed a comprehensive, integrated analysis of available hydrogeologic data to develop a numerical groundwater-flow model of the Edwards-Trinity and related aquifers in the study area in parts of...

All computer models are simplified and imperfect simulators of complex natural systems. The discrepancy arising from simplification induces bias in model predictions, which may be amplified by the process of model calibration. This paper presents a new method to identify and quantify the predictive consequences of calibrating a simplified computer model. The method is based on linear...

The U.S. Geological Survey (USGS), in cooperation with the Texas State Soil and Water Conservation Board, developed and applied an approach to create a linkage between the published upper Guadalupe River Soil Water Assessment Tool (SWAT) brush-management (ashe juniper [Juniperus ashei]) model and the full authorization version Guadalupe River Water Availability Model (WAM). The SWAT...

The implementation characteristics of two method of L-moments (MLM) algorithms for parameter estimation of the 4-parameter Asymmetric Exponential Power (AEP4) distribution are studied using the R environment for statistical computing. The objective is to validate the algorithms for general application of the AEP4 using R. An algorithm was introduced in the original study of the L-moments...