Selected precipitation characteristics in Antelope Valley, Mojave Desert, CA

An urban hydrology study currently in progress in Antelope Valley, California, includes the collection and analyses of precipitation and runoff data. Storms in Antelope Valley are most prevalent during the months of December, January, February, and March, but major storms have occurred during all months of the year except April, June, and July. The areal distribution of precipitation in the valley is influenced by the San Gabriel and Tehachapi Mountains. The rapid change in precipitation intensity with altitude causes large variations in precipitation amounts in basins of close proximity. An analysis of storm-precipitation intensity-duration data for 6 storms during 1938-92 indicates that duration of storm activity ranges from 1 to 4 days, depending on the intensity of the storm. Runoff from a completely urbanized basin averaged 27 percent of precipitation volume for 13 storms from 1989 to 1992. Significant valley-wide storms were recorded in 1943 and 1983 with 1-day precipitation amounts of as much as 5.00 inches; recurrence intervals for storms in those 2 years ranged from 11 to more than 100 years. The February 1992 storm, with 1-day precipitation of 1.51 inches at Palmdale, has a recurrence interval of 3 years. The February 1992 storm produced flooding in Palmdale and Lancaster.