The Effect of an Intensive Summer Thunderstorm on a Semiarid Urbanized Watershed

Abstract

The University of Arizona Atterbury Experimental Watershed, located southeast of Tucson, Arizona has been instrumented for precipitation and runoff measurements since 1956. Early on the afternoon of July 16, 1975 an intense convective thunderstorm produced more than three inches of rainfall in less than 50 minutes as recorded in several rain gages located in the middle of one 8.1 square-mile desert subwatershed. Storm runoff from this rural subwatershed and an adjacent recently urbanized subwatershed filled the newly finished Lakeside Reservoir and topped the concrete flood spillway with a peak of greater than 3000 cfs, the greatest flow since monitoring began. An analysis of storm characteristics, along with previously available data from local urbanized watersheds, allows speculation on the effect of such an intensive storm in a highly urbanized.area.