SPATIAL DISTRIBUTION OF RAINFALL CHARACTERISTICS ASSOCIATED WITH DEBRIS FLOWS IN THE 2004-2005 SEASON IN SOUTHERN CALIFORNIA
The rainfall characteristics, and their spatial distributions at critical times, can be compared for the 2004-2005 events, as well as with a multi-year database of archival rainfall in southern California covering storm periods known to have produced significant debris-flow activity. Rain gage distribution is not uniform across the area, and reporting practices vary from county to county; CDEC and NCDC also use different reporting formats. Still, maps using station locations and graphs of cumulative season rainfall, variations of intensity with time, ratios of cumulative seasonal rainfall to mean annual precipitation, and rain accumulations in excess of selected thresholds provide a basis for interpreting reconnaissance observations. Most of the debris flows occurred during the October and December-January storm episodes. Although rains in February and March contributed to exceptional seasonal totals, few additional debris flows were observed during repeats of earlier traverses.