Development of an Isohyetal Analysis for Oregon Using the Prism Model

by George H. Taylor, Oregon State Univ, Corvallis, United States,
Christopher Daly, Oregon State Univ, Corvallis, United States,
Wayne P. Gibson, Oregon State Univ, Corvallis, United States,



Document Type: Proceeding Paper

Part of: Engineering Hydrology

Abstract:

PRISM (Precipitation-elevation Regressions on Independent Slopes Model) is an analytical model that uses point data and a digital elevation model (DEM) to generate gridded estimates of monthly and annual precipitation. PRISM is uniquely suited to regions with mountainous terrain because it incorporates a conceptual framework that addresses the spatial scale and pattern of orographic precipitation. This paper presents a brief overview and evaluation of PRISM as applied to the entire United States. The development of an updated isohyetal analysis for the state of Oregon is discussed. Using precipitation data from the National Climatic Data Center and the Soil Conservation Service, PRISM generated estimates of precipitation values for each grid cell. The gridded output was then imported into a geographic information system (GIS) for plotting and map creation. Data were made available to interested users in both hardcopy (map) and digital (numerical matrix) format. The updated isohyetal analysis is thought to be of quality and accuracy comparable to that of traditional labor-intensive methods of a fraction of the cost.

Subject Headings: Precipitation | Information systems | Geographic information systems | Regression analysis | Prism | Spatial distribution | Model accuracy | United States | Oregon

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