Geology topics

G.S. Outlaw

Publications and source records attributed to G.S. Outlaw.

3 recordsLinked to original sources

USGS1996

Flood-frequency and detention-storage characteristics of Bear Branch watershed, Murfreesboro, Tennessee

The U.S. Geological Survey's Distributed Routing Rainfall-Runoff Model [DR3M] was applied to a 2.27-square-mile portion of Bear Branch watershed at Murfreesboro, Tennessee, to demonstrate the application of this model to small urban watersheds in central Tennessee. Kinematic wave theory was used to route excess rainfall overland and through a branched system of stream channels. The model was calibrated with hyetographs from two raingages, hydrographs from two streamflow gages, and peak-stage elevations from two crest-stage gages that were operated in the watershed from March 1989 through July 1992. Standard errors of estimate for peak discharge at Northfield Boulevard and Compton Road are 41.1 and 92.2 percent, respectively. Standard errors of estimate for runoff volumes at Northfield Boulevard and Compton Road are 53.5 and 97.6 percent, respectively. The calibrated model was used to simulate flood hydrographs for 73 large storms occurring during the period 1901-1990 and the simulated flood peaks were used to develop flood-frequency relations for present (1992) conditions in the watershed. Flood discharges for the 100-year recurrence-interval storm were estimated as 350 cubic feet per second at Northfield Boulevard, 1,000 cubic feet per second upstream of DeJarnett Lane, 610 cubic feet per second downstream of DeJarnett Lane, 800 cubic feet per second upstream of Osborne Lane, 790 cubic feet per second downstream of Osborne Lane, and 1,000 cubic feet per second at Compton Road. The effect of detention storage on flood hydrographs was simulated at several locations in the watershed. Detention storage upstream of DeJarnett Lane significantly reduces downstream flood peaks, whereas detention storage upstream of Osborne Lane has almost no effect. The results of this study indicate that the Distributed Routing Rainfall-Runoff Model could be an important tool for testing the effects of future development and flood storage alternatives on flooding in small urban watersheds throughout the area.

Water-Resources Investigations Report↗

USGS1995

Methods for assessing channel conditions related to scour-critical conditions at bridges in Tennessee

The ability to assess quickly the potential for scour at a bridge site, to evaluate those bridges with the greatest potential for significant amounts of scour, and to then identify scour-critical structures is important for public protection and bridge maintenance planning. A bridge-scour assessment information form was developed for collecting data describing the bridge site; the hydraulic geomorphic, and vegetation characteristics of the channel. Information from site assessments of 3,964 bridges in Tennessee was used to develop indexes of potential scour characteristics over broad geographic areas, such as counties, regions, or drainage basins. Channel instability charac- teristics differ from region to region. In west Tennessee counties, channel instability has progressed from valley bottoms into the uplands through headward degradation. In middle and east counties of Tennessee, channel widening is a dominant process, but widespread degradation has been prevented by stream beds being lines with erosion-resistant bedrock, boulder, cobble, and gravel, and by the absence of channelization. Neither quantifiable headcutting nor degradation in bedrock channels was noted at any site in the State. However, potential for lateral scour is prevalent in Middle and East Tennessee.

Water-Resources Investigations Report↗

USGS1992

Rainfall, streamflow, and peak stage data collected at the Murfreesboro, Tennessee, gaging network, March 1989 through July 1992

Rainfall, stage, and streamflow data in the Murfreesboro area, Middle Tennessee, were collected from March 1989 through July 1992 from a network of 68 gaging stations. The network consists of 10 tipping-bucket rain gages, 2 continuous-record streamflow gages, 4 partial-record flood hydrograph gages, and 72 crest-stage gages. Data collected by the gages includes 5minute time-step rainfall hyetographs, 15-minute time-step flood hydrographs, and peak-stage elevations. Data are stored in a computer data base and are available for many computer modeling and engineering applications.

Tennessee↗