|Mendez Delgado, Aida - USDA-ARS (RESIGNED)|
|Osborn, Herbert - ARS COLLABORATOR (RET.)|
Submitted to: Proceedings Arizona Hydrological Society Symposium
Publication Type: Proceedings
Publication Acceptance Date: September 23, 1999
Publication Date: N/A
Technical Abstract: Runoff from small watersheds in the southwestern United States is dominated by intense, short-duration convective rains of limited spatial extent (Osborn and Laursen, 1973). Storm drainage design is often based on rainfall information published by the National Weather Service in the National Oceanic and Atmospheric Administration (NOAA) Atlas 2 series (Miller et al., 1973). It is believed that runoff from these types of storms is over-predicted, because rainfall is over-predicted, since the depth area rainfall values estimated using the point-to-area conversion ratios given by the depth area monogram curves in the NOAA Atlas 2 are overestimated, according to Osborn et al. (1980) findings. The NOAA curves were based on a 2-yr data set and were developed with data from outside the Southwest, while Osborn et al. (1980) curves were based on point-to-area conversion ratios for 30, 60, 120, and 360 min duration rainfalls for 2, 10, and 100-yr frequencies for areas of 0, 50, 100, 150, and 200 km2 using 20 yrs of records of raingages distributed at about 1 per 3 km2 at the USDA-ARS Walnut Gulch Experimental Watershed. In the present study, the areal and point maximum annual 10-min duration rainfall depths have been computed for 5 watersheds ranging from 2.3 to 149.0 km2 based on rainfall records from 1975 to 1991. The data, the procedure employed and the initial results will be presented at the Arizona Hydrological Society Symp. '98.