| Description |
vi, 78 leaves : illustrations, photographs ; 29 cm |
| Summary |
""A problem of prime importance to the river forecaster is that of estimating what portion of the rain falling during a storm will be absorbed by the soil and what portion will run off the land surface, thus contributing to flood flows. This problem is directly related to the moisture content of the soil and, consequently, observations of soil moisture should be of direct benefit in flood forecasting. Moreover, soil-moisture data are a valuable adjunct to the climatological records which for many years have been collected by the Weather Bureau." Small area drainage basins are particularly important in highway engineering. A few years ago 51 percent of all funds spent for State-Federal water way structures were for spans of 20 feet or less. "The hydrologic data available for the design of small drainage structures is pitifully small when one considers the investment that is being made in such structures." In recent years the U.S. Geological Survey, Water Resources Division has directed considerable work toward the collection of basic data on small drainage areas. This information should prove invaluable to state where these studies are going on with the present trend in increased highway construction. Any additional information on the rainfall runoff relation of a small watershed would be of practical value because of the short periods of record of existing data and in many cases the complete absence of data. There are many variables in the rainfall runoff relationship for any drainage basin; total precipitation, rate of precipitation, soil moisture, surface slope, type of vegetation, type of soil, distribution of precipitation, temperature, humidity, season of the year, etc. The many variables become more complex as the size of the drainage area is increased. If the drainage area is decreased, the variables become less complex but an additional error is introduced in expanding the relationships to an area of larger size for practical application. This thesis is directed toward the collection of basic data on soil moisture in relation to runoff. A natural drainage basin of 0.227 square miles (measured by transit stadia survey) was selected for this study"--Introduction, leaves 2-4. |
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