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Philip Hadley Carrigan

Publications and source records attributed to Philip Hadley Carrigan.

3 recordsLinked to original sources
USGS1977

User's guide for U.S. Geological Survey rainfall-runoff models; revised 1977

Modified versions of the rainfall-runoff model described by Dawdy, Lichty, and Bergmann (1972) (see W72-11754) are used in the U.S. Geological Survey as a means of synthesizing flood discharges for small drainage areas. Synthesized flood discharges derived through use of long-term (60-70 year) rainfall and evaporation data, provide a more representative time base than do short-term (5-15 year) discharge records obtained by conventional stream gaging techniques. The rainfall, discharge, and evaporation data for use with rainfall-runoff models are stored in the Unit and Daily Values Files. Any of these data which were collected during the current or immediately preceding water year are stored on direct access, online disk files. Older data are stored in sequential files on magnetic tapes. Both the disks and tapes contain short-term data collected by the U.S. Geological Survey for calibration of models and long-term data for use in synthesis of long-term flood records. Information in this report provides guidelines for the assembly, storage, and retrieval of data needed to use these models, and also provides description and documentation of computer programs for model calibration and flood-record synthesis. (See also W74-11234) (Woodard-USGS)

Open-File Report↗
USGS1975

Optimizing information transfer in a stream-gaging network

Networks of small stream (drainage area less than 50 square miles or 130 square kilometres) flood gages have been operated throughout the country for a number of years to supplement flood information already available for large streams. The goal in operating these networks has been to obtain sufficient data for estimating flood frequency at ungaged sites with the equivalent accuracy expected from 10 years of observed flood records. In some areas the networks have accumulated sufficient data to satisfy these accuracy goals. A review of these networks, looking toward possible reduction of the number of gages, is now timely. Continued operation of a few selected gages may be desirable to provide a longer time-sample base for improving the flood-frequency estimating equation and(or) to expand the area over which the equations apply. In 1974, Thomas Maddock III developed a rational method for selecting gages to be retained in a reduced hydrologic network. This method of network analysis seeks the optimum set of gages to be retained for a given level of annual operating costs with the information content of the reduced network being the factor optimized. Application of Maddock's method demonstrated that a considerable number of gages could be eliminated from a network without grossly decreasing its information content. Maddock's method of analysis is described in detail for a hypothetical network of gages. The method also is applied to actual networks in Montana, Illinois, and Georgia. The analysis of networks in Montana illustrates the basic approach to selecting an optimal subset from the existing set of gages. The Illinois analysis demonstrated that by retaining only 26 percent of the gages, nearly 63 percent of the original information is retained in the reduced network. Application of the procedure shows how the design of networks in Georgia may be modified because of hydrologic considerations to meet budgetary constraints.

Water-Resources Investigations Report↗