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Clarence R. Gilbert

Publications and source records attributed to Clarence R. Gilbert.

3 recordsLinked to original sources
USGS1970

Hydrologic effects of floodwater-retarding structures on Garza-Little Elm Reservoir, Texas

The Texas District of the Water Resources Division of the U.S. Geological Survey has collected and analyzed hydrologic data since 1953 to define the effects of systems of floodwater-retarding structures on downstream water and sediment yield. The district project includes 11 study areas ranging from 18 to 80 square miles in size and from 0 to 67 in percent of study area controlled by floodwaterretarding structures. The 11 study areas are within that part of Texas where the west-to-east average annual runoff ranges from about 2 to 7 inches. This report presents results of analyses, development of methodolgy, and results of application of methods for defining the downstream effects of systems of floodwaterretarding structures. Annual inflow to and outflow from the system of floodwater-retarding reservoirs in seven of the 11 study areas were found to be related by the equation: O=0.98/ 0.68, where O is annual outflow, in inches, and / is annual net inflow, in inches. Transmission loss of structure outflow to the downstream study-area stream-gaging station was determined and compared with the transmission loss of natural flood flow between tandem stream-gaging stations on Denton Creek, a tributary to Elm Fork Trinity River above Dallas. Trap efficiency of most floodwater-retarding structures was found by the U.S. Soil Conservation Service to be about 97 percent. Downstream increases in suspended-sediment concentration in the outflow were found to be large in a study area with mostly silt and clay sediments, but even a large increase in suspendedsediment concentration did not represent a significant quantitative pickup of sediment by the outflow water. Water consumption in floodwater-retarding reservoirs from the combined actions of evaporation, evapotranspiration, and seepage was found to be as much as twice the average annual consumption attributable to evaporation alone. Average annual consumption in reservoirs in the seven study areas analyzed ranged from 1.57 inches of equivalent runoff in the easternmost study area, where annual runoff averaged 6.96 inches, to 0.77 inch of equivalent runoff in the westernmost study area, where the average annual runoff was 2.35 inches. The effect of consumption on downstream flow is partially offset by rainfall on pool surface. Studies covering as much as 15 years of streamflow record at the stream-gaging stations that gage outflow from the Deep and Honey Creek study areas indicated no increase in base flow. Multiple-linear-regression techniques were used in developing methodology to determine reservoir consumption in seven study areas. The physical and climatic fnctors influencing consumption were grouped as variables in regard to their relative effect on the actions of evaporation, evapotranspiration, and seepage. The resulting generalized equation was then used in synthesizing the consumptive effects of a planned system of 162 floodwater-retarding reservoirs controlling 26 percent of a 1,660-square-mile drainage basin upstream from a major water-supply reservoir. The analyses were based on the assumption that all water consumed at the floodwater-retarding reservoirs would have reached the downstream watersupply reservoir. Water-sediment discharge relationships were derived for the runoff into the structures as well as for the runoff through and below the structures. A mathematical response model of the floodwater-retarding reservoir systems and the entire drainage basin was computer programed to yield monthly water and sediment inflow to the water-supply reservoir. Results of the response model showed that with full development, depletion of annual yield to the large reservoir would be as much as 10 percent in the early years; but after the permanent pools of the floodwater-retarding structures had mostly filled with sediment, depletion of annual yield would be generally less than 1 percent. The depletion of yield to Garza-Little Elm Reservoir during the 39-year synthesized period of study was estimated as 296,800 acre-feet out of 18,256,000 acre-feet total yield. During the same period, the floodwater-retarding structures were estimated to have kept 19,700 acre-feet of sediment from being deposited in the reservoir. "Firm"- or "critical"-yield studies were made of the large reservoir on the basis of two sets of conditions : with floodwater-retarding structures in the drainage basin, and without such structures. Results of the firm-yield studies indicated that with full development, annual firm yield would be initially reduced by 10 percent. After 30 or more years, when the permanent pools of the floodwaterretarding reservoirs would be mostly filled with sediment, the firm yield would be almost the same with or without the upstream development.

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USGS1964

Hydrologic studies of small watersheds, Honey Creek basin, Collin and Grayson Counties, Texas, 1953-1959

This report presents the results of an investigation into the effects of floodwaterretarding structures in the 39 square miles of the Honey Creek basin above the stream-gaging station near McKinney, during the period October 1952 to September 1959. The number of such structures in the study area was increased from 2 to 12 during the investigation. Data were collected which permit computation of basin and watershed precipitation, inflow to and outflow from each floodwater-retarding structure, evaporation and seepage from each pool, and a continuous record of discharge from the entire study area. Transpiration was not evaluated, but in the water-budget summary it is included in the item "pool consumption", together with evaporation and seepage. During the 7-year study period, the annual inflow to the gaged pools ranged from 1.34 to 26.50 inches and averaged 7.39 inches, of which 0.73 inch was direct rainfall on the pool surface. The annual pool consumption ranged only from 1.33 to 1.85 inches, and averaged 1.62 inches. These results indicate that in a year of substantial runoff the floodwater-retarding structures would have only a minor effect on downstream water yield, but in a year of low runoff the structures would have a marked effect on downstream water yield. The effect on the flood regimen at a downstream point because of floodwaterretarding structures in the headwaters will vary with the amount and intensity of the precipitation and with antecedent conditions. The beneficial effects of the structures on Honey Creek during the floods of April and May 1957 is illustrative. During the period April 19 to May 31, 1957, the total volume of inflow to the floodwater-retarding structures was equivalent to 4.3 times the combined capacities of the pools from an average basin rainfall of 30.31 inches. The retarding effects of the structures limited the flooding on Honey Creek at the gage to minor flooding on only five occasions during that period.

Texas↗
USGS1963

Floods on White Rock Creek above White Rock Lake at Dallas, Texas

The White Rock Creek watershed within the city limits of Dallas , Texas, presents problems not unique in the rapid residential and industrial development encountered by many cities throughout the United States. The advantages of full development of the existing area within a city before expanding city boundaries, are related to both economics and civic pride. The expansion of city boundaries usually results in higher per capital costs for the operation of city governments. Certainly no responsible city official would oppose reasonable development of watersheds and flood plains and thus sacrifice an increase in tax revenue. Within the words "reasonable development" lies the problem faced by these officials. They are aware that the natural function of a stream channel, and its associated flood plain is to carry away excess water in time of flood. They are also aware that failure to recognize this has often led to haphazard development on flood plains with a consequent increase in flood damages. In the absence of factual data defining the risk involved in occupying flood plains, stringent corrective and preventative measures must be taken to regulate man's activities on flood plains to a point beyond normal precaution. Flood-flow characteristics in the reach of White Rock Creek that lies between the northern city boundary of Dallas and Northwest Highway (Loop 12) at the upper end of White Rock Lake, are presented in this report. Hydrologic data shown include history and magnitude of floods, flood profiles, outlines of areas inundated by three floods, and estimates of mean velocities of flow at selected points. Approximate areas inundated by floods of April 1942 and July 1962 along White Rock Creek and by the flood of October 1962 along Cottonwood Creek, Floyd Branch, and Jackson Branch, are delineated on maps. Greater floods have undoubtedly occurred in the past but no attempt is made to show their probable overflow limits because basic data on such floods could not be obtained. Depths of inundation can be estimated from the information shown. Elevations shown are in feet above mean sea level, datum of 1929. The data and computations supporting the results given herein are in the files of the Geological Survey in Austin, Texas.

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