A methodology of rainfall data analysis and stochastic rainfall/runoff synthesis

Abstract

Precipitation data analysis procedures are presented that allow development of the random variables of interest describing the summer and winter rainfall process in semiarid regions of the West. These procedures include programs that define the variables of event interarrival time and rainfall amount per event and a process of grouping months within these variables. A program for analyzing winter frontal storm activity is presented. Procedures are developed describing the actual distributions of the annual rainfall process. A methodology for fitting theoretical distributions to each of these actual distributions is explained. Climactic data from the Hanford Meteorology Station NW of Richland, Washington is used to develop these procedures. Results of the analysis procedures for the Hanford data are included. The results of the above analysis are incorporated into a stochastic rainfall model that includes a direct surface runoff calculation process. This runoff is calculated using the Soil Conservation Service method. The resulting stochastic model allows a study of the change in watershed practices that can greatly assist in making management decisions concerning possible water harvesting practices on western mine sites.