The soil conservation service uses a dimensionless unit hydrograph to develop storm hydrographs for hydrologic evaluation of small watersheds and for hydrologic design of conservation measures. An average dimensionless unit hydrograph has been used extensively nationwide with reasonable success. However, in flatlands such as the atlantic coastal plains, stream gauge analysis indicates that another shaped dimensionless unit hydrograph that is signficantly different from the average should be used. An average dimensionless unit hydrograph for coastal flatlands was developed by using the techniques in the u.S. Army corps of engineers hec-1 computer program. An average c sub p value for the snyder unit hydrograph was determined from sevenevents on four streams. The flatland unit hydrograph was then used to generate peakflow frequency curves with reasonable success at thefour stream gauge sites plus one additional site. This paper appears in transportation research record no. 1224, Rest areas, wetlands, and hydrology.
Samenvatting