Novel Approaches to Simulate Flood Inundation from Manholes and Watersheds PDF Download

Author: Merhawi GebreEgziabher GebreMichael
Publisher:
ISBN:
Category : Floods
Languages : en
Pages : 0

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Book Description
Flood prediction and forecast for watershed and urban areas are critical for planning stormwater systems and assessing flood risks. While some hydrodynamic models can simulate flood inundation, most of these models are commercial and require large datasets and computational resources that limit their applications. This study developed two simplified and computationally efficient flood mapping models for delineating flood hazard zones using readily available datasets. The first model, flood inundation and recession model (FIRM), was developed using digital elevation maps to predict flooding associated with manhole overflow during and following flood events. The model was coupled with the 1D Storm Water Management Model (SWMM) to characterize the spatial extent and depth of manhole flooding and recession. I tested the coupled model for two manhole flooding events in Edmonds, WA. The results show a reasonable match between the observed and modeled flood areas, highlighting the importance of considering manholes in urban flood simulations. The second model delineates flood extent and depth at the catchment level using the NRCS curve number method for runoff productions at grids and a computationally efficient flood routing method. The gridded runoff estimated by the NRCS method is used as input to the flood inundation model that iteratively routes the runoff based on elevation variation, flood connectivity, and the assumption of level-water surface propagation. I tested the model using the recent flood event in the upper Umatilla River watershed. Several statistical criteria were used to evaluate the model's performance by comparing the simulation results with the reconstructed flood boundaries delineated using photos and drone videos during the flood event. The results demonstrate the model's ability to simulate and predict flood extent and depth accurately within the watershed. Due to its computational efficiency and its uses of readily available datasets, the model is suitable for near real-time flood forecast and early warning decisions. The model is also useful for determining the flood level associated with design storms obtained from the intensity-duration-frequency (IDF) curves, further improving stormwater system designs.