Estimation of Grid-based Design Floods for Stormwater Applications

Abstract:

With the increasing flood events across the globe, there is a growing interest in improving flood forecasting and the design of stormwater systems. Most stormwater infrastructures are designed directly using the design storms obtained from rainfall intensity-frequency-duration (IDF) curves. However, due to the difference between design storms and floods IDF, there is a need to estimate the floods from readily available rainfall IDF curves to design the stormwater system better. This presentation will introduce a new model that predicts flood depth and discharge for each grid by identifying the contributing drainage areas and the runoff generated from the regions. The model results include grid-level flood IDF curves and flood risks under existing drainage networks. The model was evaluated using two hydrologically different test-cases in the United States, including the 1,150 km2 upper Umatilla River watershed in Oregon and the 545 km2 Onion Creek watershed in Texas.