Instant Information about Water Conditions: Ask the River to Text You a Water Alert!!
(Press Release May 17, 2010)
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New Publication:  Quantifying Components of the Hydrologic Cycle in Virginia using Chemical Hydrograph Separation and Multiple Regression Analysis

This study by the U.S. Geological Survey, prepared in cooperation with the Virginia Department of Environmental Quality, quantifies the components of the hydrologic cycle across the Commonwealth of Virginia. Long-term, mean fluxes were calculated for precipitation, surface runoff, infiltration, total evapotranspiration (ET), riparian ET, recharge, base flow (or groundwater discharge) and net total outflow. Fluxes of these components were first estimated on a number of real-time-gaged watersheds across Virginia. Specific conductance was used to distinguish and separate surface runoff from base flow. Specific-conductance data were collected every 15 minutes at 75 real-time gages for approximately 18 months between March 2007 and August 2008. Precipitation was estimated for 1971–2000 using PRISM climate data. Precipitation and temperature from the PRISM data were used to develop a regression-based relation to estimate total ET. The proportion of watershed precipitation that becomes surface runoff was related to physiographic province and rock type in a runoff regression equation.

New Publication:  Low-Flow Characteristics of Virginia Streams

Low-flow annual non-exceedance probabilities and regional regression equations describe low-flow characteristics of Virginia streams. Statistical methods are used to evaluate and summarize low-flow data collected from 1895 through 2007. Methods are provided for estimating low-flow of gaged and ungaged streams, including 1-, 4-, 7-, and 30-day average low-flow characteristics. Stream basin characteristics are used as explanatory variables in regression models of 1-, 4-, 7-, and 30-day average low-flow annual non-exceedance probabilities for six physiographic regions. Regression equations developed using the Maintenance of Variance with Extension (MOVE.1) method describe low-flow characteristics at short-term, continuous-record, and partial-record streamgaging stations. Monthly streamflow statistics, base-flow indices, and flow-duration curves are also provided. This study supersedes previous studies of low flows in Virginia.