TY - JOUR
T1 - The impact of the spatiotemporal structure of rainfall on flood frequency over a small urban watershed
T2 - An approach coupling stochastic storm transposition and hydrologic modeling
AU - Zhou, Zhengzheng
AU - Smith, James A.
AU - Baeck, Mary Lynn
AU - Wright, Daniel B.
AU - Smith, Brianne K.
AU - Liu, Shuguang
N1 - Publisher Copyright:
© Author(s) 2021.
PY - 2021/8/31
Y1 - 2021/8/31
N2 - The role of rainfall space-time structure, as well as its complex interactions with land surface properties, in flood response remains an open research issue. This study contributes to this understanding, specifically for small (<15 km2) urban watersheds. Using a flood frequency analysis framework that combines stochastic storm transposition (SST)-based rainfall scenarios with the physically based distributed Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model, we examine the role of rainfall spatial and temporal variability in flood frequency across drainage basin scales in the highly urbanized Dead Run watershed (14.3 km2), Maryland, USA. The results show the complexities of flood response within several subwatersheds for both short (<50 years) and long (>100 years) rainfall return periods. The impact of impervious area on flood response decreases with increasing rainfall return period. For extreme storms, the maximum discharge is closely linked to the spatial structure of rainfall, especially storm core spatial coverage. The spatial heterogeneity of rainfall increases flood peak magnitudes by 50% on average at the watershed outlet and its subwatersheds for both small and large return periods. The framework of SST-GSSHA-coupled frequency analysis also highlights the fact that spatially distributed rainfall scenarios are needed in quick-response flood frequency, even for relatively small basin scales.
AB - The role of rainfall space-time structure, as well as its complex interactions with land surface properties, in flood response remains an open research issue. This study contributes to this understanding, specifically for small (<15 km2) urban watersheds. Using a flood frequency analysis framework that combines stochastic storm transposition (SST)-based rainfall scenarios with the physically based distributed Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model, we examine the role of rainfall spatial and temporal variability in flood frequency across drainage basin scales in the highly urbanized Dead Run watershed (14.3 km2), Maryland, USA. The results show the complexities of flood response within several subwatersheds for both short (<50 years) and long (>100 years) rainfall return periods. The impact of impervious area on flood response decreases with increasing rainfall return period. For extreme storms, the maximum discharge is closely linked to the spatial structure of rainfall, especially storm core spatial coverage. The spatial heterogeneity of rainfall increases flood peak magnitudes by 50% on average at the watershed outlet and its subwatersheds for both small and large return periods. The framework of SST-GSSHA-coupled frequency analysis also highlights the fact that spatially distributed rainfall scenarios are needed in quick-response flood frequency, even for relatively small basin scales.
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U2 - 10.5194/hess-25-4701-2021
DO - 10.5194/hess-25-4701-2021
M3 - Article
AN - SCOPUS:85114271089
SN - 1027-5606
VL - 25
SP - 4701
EP - 4717
JO - Hydrology and Earth System Sciences
JF - Hydrology and Earth System Sciences
IS - 9
ER -