History of Small Watershed Projects in Texas
The U.S. Soil Conservation Service is actively engaged in the installation of flood and soil erosion reducing measured in Texas under the authority of "The Flood Control Act" (Public Law 566), as amended. In June 1968, the Soil Conservation Service estimated approximately 3,500 structure to be physically and economically feasible for installation in Texas. As of September 30, 1968, 1,271 of these structures had been built.
This watershed-development program will have varying but important effects on the surface and ground-water resources of river basins, especially where a large number of the floodwater-retarding structures are built. Basic hydrologic data are needed to appraise the effects of the structures on water yield and the mode of occurrence of runoff.
Hydrologic investigations of these small watersheds were begun by the Geological Survey in 1951 and are now being made in 11 areas (fig. 1). These studies are being made in cooperation with the Texas Water Development Board, the Soil Conservation Service, the San Antonio River Authority, the city of Dallas, and the Tarrant County Water Control and Improvement District No. 1. The 11 study areas were chosen to sample watersheds having different rainfall, topography, geology, and soils. In four of the study areas (Mukewater, North, Little Elm, and Pin Oak Creeks), streamflow and rainfall records were collected prior to construction of the floodwater-retarding structures, thus affording the opportunity fo analyses of the conditions "before and after" development. Structures have now been built on three of these study areas. A summary of the development of the floodwater-retarding structures on each study area as of September 30, 1968, is shown in table 1.
Purpose and Scope of this Basic-Data Report
This report, which is the ninth in a series of basic-data reports published annually for the Little Elm Creek study area, contains the rainfall, runoff, and storage data collected during the 1968 water year for the 75.5-square mile area above the stream-gaging station Little Elm Creek near Aubrey, Texas. The location of floodwater-retarding structured and hydrologic instruments in the area are shown on figure 2.
This investigation was scheduled to continue through a period of both above- and below-normal precipitation to define the various factors used in the analyses of rainfall-runoff relationships before and feter floowater-retarding structures are built.
To facilitate the publication and distribution of this repoirt at the earliest feasible time, certain material contained herein does not conform to the formal publication standards of the U.S. Geological Survey.