Geostatistical analysis of the spatial distribution of precipitation in the San Francisco Bay Area from 1890 to 2013: a GIS approach

This study has modeled spatial distribution of precipitation in the San Francisco Bay Area using geostatistical analysis in a GIS to aid regional water resource managers and planners. The main objectives of this study were: (1) use geostatistical methods to estimate, analyze, model and characterize the spatial variability of precipitation over 124 years from 1890 to 2013 using measured and simulated rain gauge data, (2) interpolate 49 precipitation maps representing 5 climate time periods spanning 31 years within the 1890 to 2013 timeline. Precipitation data from a combination of 58 weather station rain gauges was collected across 10 counties surrounding the San Francisco Bay region. Geostatistical analysis provided a set of statistical tools for incorporating the spatial correlation of measured and simulated observations to interpolate a continuous rainfall surface. All maps showed a consistent trend of precipitation rain bands. Highest values were located in the northwest, gradually decreasing to the lowest precipitation values in the southeast section of the study area. Storms generated in the Pacific Ocean were shown to track primarily from the northwest to the southeast. Topographical influences of the coastal ranges and valley basins displayed orographic effects that were visually displayed by the spatial distribution of precipitation on all maps. Results of this study confirm other research using geostatistical techniques, that for low-density rain gauge networks, geostatistical interpolation is a feasible option for spatial representation of local and regional precipitation in the San Francisco Bay Area.