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Mapping Dependence Between Extreme Rainfall and Storm Surge
Author(s) -
Wu Wenyan,
McInnes Kathleen,
O'Grady Julian,
Hoeke Ron,
Leonard Michael,
Westra Seth
Publication year - 2018
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2017jc013472
Subject(s) - storm surge , surge , environmental science , flood myth , climatology , coastal flood , bathymetry , storm , tide gauge , meteorology , extreme value theory , geology , sea level , oceanography , climate change , geography , sea level rise , statistics , mathematics , archaeology
Dependence between extreme storm surge and rainfall can have significant implications for flood risk in coastal and estuarine regions. To supplement limited observational records, we use reanalysis surge data from a hydrodynamic model as the basis for dependence mapping, providing information at a resolution of approximately 30 km along the Australian coastline. We evaluated this approach by comparing the dependence estimates from modeled surge to that calculated using historical surge records from 79 tide gauges around Australia. The results show reasonable agreement between the two sets of dependence values, with the exception of lower seasonal variation in the modeled dependence values compared to the observed data, especially at locations where there are multiple processes driving extreme storm surge. This is due to the combined impact of local bathymetry as well as the resolution of the hydrodynamic model and its meteorological inputs. Meteorological drivers were also investigated for different combinations of extreme rainfall and surge—namely rain‐only, surge‐only, and coincident extremes—finding that different synoptic patterns are responsible for each combination. The ability to supplement observational records with high‐resolution modeled surge data enables a much more precise quantification of dependence along the coastline, strengthening the physical basis for assessments of flood risk in coastal regions.