FLOOD10200 - Laserfiche WebLink

Home Browse Search

r- Storm Rainfall (CSR) model. CSR model output of peak storm total rainfall, temporal distribution of rainfall in 10 minute steps, storm duration and peak 10-, 30- and 50-minute intensities were calculated. r ~ 3. The CSR model output was compared to historical rainfall records of peak point storm total, intensity values and temporal distributions. Comparison of model peak point rainfall for the three storms are shown in Figure 5. 4. The temporal distribution of the CSR model peak point rainfall was then applied in a proportional manner to each 0.5 inch of isopluvial band in the historical rainfall surveys to obtain the temporal rain- fall within each of the subbasins. Since each convective storm sur- veyed covered a n!l.atively large area, more than one CSR model run was needed to cover each storm profile. B. Transposition of the historic storm events over the Boulder Creek watershed. 1. A prime consideration in the dynamic transposition of a storm event over a watershed is the relationship between the winds in the sub- cloud and cloud layers. The winds in the sub-cloud layer provide the source of moist energy for the storm's growth. These winds establish the location of the updraft within the storm. The cloud layer winds strongly influence the general direction of movement of the storm. The vector difference of the two winds establishes the propogation or general movement pattern of raincells within the storm complex. In essense this vector establishes the axis of ellipticity of the rain- fall field. 2. Using the upper air temperature, moisture and wind field observations for the storm event used in the reconstitution, the elevation of the cloud base is obtained and the degree of lift required for its forma- tion. This elevation is compared to the elevation profile of the basin and is used to fix the elevation location of the rainfall field. 9