Storm Motion Analysis and Characteristics for Dynamic Design Storm Development

Design storms that are representative of local or regional climatology are needed for hydrologic and hydraulic modeling of projects involving watershed response to rainfall. Representativeness includes both the temporal and spatial distribution of rainfall. Considering dynamic storms, the temporal and spatial distribution are related because the motion determines the point-scale hyetograph, while the spatial and temporal distribution of the moving storm determine the depth-area-duration relationship of the storm total. Radar offers a unique opportunity to measure the movement of storms in terms of motion, both speed and direction, and for depth-area reduction factors. This presentation examines how these design storm characteristics can be derived from radar and rain gauge data. Storm motion properties measured for a range of climatic conditions are examined for application to hydrologic/hydraulic design and risk reduction.