Basin Rotation Method to Quantify the Effect of Rainstorm Movement on Flood Peak Response

Abstract:

In this study, the authors investigate effect of directional influence of storm movement on catchment flood peak response using the synthetic circular basin. Due to complexity in defining storm movements, which requires meteorological modeling, we adopt a novel approach called basin rotation method (BRM). A systematic basin rotation approach provides a proxy for the storm movement relative to the river network topology to study its hydrologic response. The authors use Stage-IV rainfall with 4-km by 1-hour resolution for 16 years period from 2003 to 2018 in Iowa, U.S. They systematically analyze consequent flood peak response pertaining to storm movements (basin rotations) using a distributed hydrologic model called Hillslope-Link Model (HLM). The HLM model has demonstrated the ability to reproduce observed streamflows for real river basins studied in Iowa. Through hydrologic simulations, the authors show that the BRM approach can aptly quantify the relationship between directional influence of rainstorm and hydrologic response. They show that the maximum flood peak response is strongly dependent on the interaction of peak of rainstorm with the peak of the width function, which corresponds to the original basin orientation in this experiment. The maximum error in the rainfall volume difference and peak difference and their inter-annual variability result from the movement of rainstorm at about 90º-105º relative to the original storm direction. The study has important implications for flood predictions and developing flood resilience and watershed management strategies.