Simulated Effects of Existing and Proposed Surface-Water Impoundments and Gas-Well Pads On Streamflow and Sediment in the Cypress Creek Watershed, Central Arkansas
Rheannon M. Hart
U.S. Geological Survey, 401 Hardin Rd., Little Rock, AR 72211, 501-228-3664
Cypress Creek is located in central Arkansas in the heart of the Fayetteville Shale play and is the main tributary to Brewer Lake. A Hydrologic Simulation Program--FORTRAN model of the Cypress Creek watershed was developed to simulate the effects of potential gas-extraction activities on streamflow and sediment transport within the 22,924 acre watershed. Continuous streamflow data and discrete suspended-sediment data (quarterly and storm-event sampling) collected from 2009 through 2012 were used to calibrate the model.
The model incorporated 2006 land-use conditions that were modified to include the current (2012) 35 gas-well pads and 6 surface-water impoundments used for hydraulic fracturing water storage. Model simulations of four alternative land-use scenarios were evaluated to examine the potential effects of these land-use changes on the streamflow and water quality entering Brewer Lake. These four scenarios included simulation of conversion of all non-forested land to forest, conversion to 1949 land use, removal of existing gas-well pads and surface-water impoundments, and addition of proposed pads and impoundments. For the removal of existing gas-well pads and impoundments scenario, average daily streamflow, average spring and summer streamflows, and average sediment loads remained relatively unchanged. For the other three scenarios, average daily streamflow, average spring and summer streamflows, and average sediment loads decreased relative to current conditions.