Development of Web-based Stochastic Storm Transposition Toolkit for Physically-based Rainfall and Flood Hazard Analysis
This project has been recognized as the FY20 Science and Technology Project of the Year.
Can more realistic representations of extreme rainfall using Stochastic Storm Transposition (SST) improve estimates of flood hazard and uncertainty? Spatial and temporal variability of precipitation can lead to a wide range of flood outcomes, only some of which have actually been experienced. The limits of historical rainfall data translate to uncertainty in flood hazard estimates. The RainyDay© software uses the SST technique to create both rainfall intensity-duration-frequency (IDF) curves and large numbers of realistic extreme rainfall scenarios from short records. SST is able to produce accurate IDF and flood estimates with return periods of at least 1000 years using only 10 years of input data, while a new 33-year, 100-member ensemble rainfall dataset will enable simulation of much rarer storms and better estimation of uncertainties. Rainfall scenarios from RainyDay can combine with hydrologic models to provide robust estimates of flood hazard and uncertainty.
Need and Benefit
The proposed research addresses Priority Areas (PA) 4.01 and 4.04 in Brekke et al., "Addressing Climate Change in Long-Term Water Resources Planning and Management" (2011). PA 4.01 is focused on determining strengths and weaknesses of watershed hydrologic methods to support scoping decisions. The proposed work speaks directly to this area by comparing results from advanced stochastic methods and rainfall-runoff models with results from previous, conventional analyses. The proposed work also addresses PA 4.04, which is focused on identifying strengths and weaknesses of spatially distributed weather data that may be used for hydrologic model development. The proposed research addresses this gap by exploring the benefits of ensemble datasets and RainyDay. The ensemble dataset should improve estimates of uncertainty surrounding precipitation observations, while the RainDay will streamline generation of precipitation inputs. Both tools may help identify future distributed data needs.
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Bureau of Reclamation Review
The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.
Stochastic Storm Transposition for Physically-Based Rainfall and Flood Hazard Analyses (final, PDF, 9.1MB)
By Kathleen D. Holman Daniel B. Wright Guo Yu
Report completed on September 30, 2020
Stochastic Storm Transposition Applications to Precipitation and Flood Frequency Analyses (final, PDF, 406KB)
By Kathleen Holman
R&D Bulletin completed on March 30, 2021