Flood Peaks from Small Southwest Range Watershed

Runoff on the 67-sq-mile Alamogordo Creek Experimental Watershed in northeastern New Mexico is generated from storm precipitation with greatly differing characteristics. The largest peak discharges occurred from a combination of convective heating and weak summer cold fronts. Thunderstorms within frontal systems have produced large peak discharges and runoff volumes, whereas the long-duration summer frontal storms have produced appreciable volumes of runoff, but much lower peak discharges. For a storm duration of less than six hours, the point precipitation frequencies appear to be higher than those published by the U.S. Weather Bureau. The data show the importance of watershed rainfall values as compared to single point values. The five largest runoff events during the 14-yr record are compared and discussed in relation to precipitation differences. By extrapolation of the available data, using a log-normal frequency distribution, the 20-yr flood was estimated to be 8,700 cfs.