REGIONAL FREQUENCY-ANALYSIS OF EXTREME PRECIPITATION IN LOUISIANA

A regional frequency analysis procedure is outlined and applied to pre cipitation data in Louisiana. A total of 92 rain gauges were used to g enerate 25 synthesized stations with long periods of record. Annual ma ximum series for rainfall durations of 1, 3, 6, 12, and 24 hr from the 25 synthesized stations were-used for various statistical analyses. T he mean annual precipitation, geographical locations, and the synoptic generating mechanisms were used to identify the three climatologicall y homogeneous regions in Louisiana. Using the L-moment ratios, the und erlying regional probability distribution was identified to be the gen eralized extreme value (GEV) distribution. The regional parameters of the GEV distribution were estimated by the indexed probability weighte d moments (PWM). The regional analysis procedure was tested by Monte C arlo simulation. Relative root-mean-square error (RRMSE) and relative bias (RBIAS) were computed and compared with those resulting from at-s ite Monte Carlo simulation. All results show that the regional procedu re can substantially reduce the RRMSE and RBIAS in quantile prediction .