Vulnerability Assessment at Village Level Due to Tides, Surges and Wave Setup

Abstract

An assessment of cyclone risk and vulnerability at the village level has evolved, which is an important component of the information system for local level development action plans for preparedness and mitigation. Here, a case study for the Nellore district along the east coast of India is considered. Using maximum probable surges along the coast, total water level (TWL) due to the combined effect of surge, tide, and wind wave is computed for the most vulnerable coastal villages of the Nellore district due to any tropical cyclones. The computations suggest that the TWL along the Nellore coast varies from 2 m in the south to 4 m in the north.

A storm surge inundation model of the northern Bay of Bengal using publicly available data

“…Further water‐level effects that contribute to the total storm tide height at the coast, such as tide–surge interaction (Johns et al , 1985), air–sea drag coefficient choice (e.g. Moon et al , 2007), and wave set‐up (which can add 0.5 m to total water levels at the coast; Jain et al , 2010) were not included in forcing the LISFLOOD‐FP inundation model. Additional water‐level uncertainty was introduced from the interpolation of tidal data, and assumptions made to generate the spatially varying water‐level time series used to force the LISFLOOD‐FP coastal boundary.…”

Bay of Bengal cyclone extreme water level estimate uncertainty

“…Furthermore, future work should investigate flood risk uncertainty due to wave set-up and tidal contributions (see Jain et al, 2010b;Sindhu and Unnikrishnan, 2011), inundation modelling uncertainties (e.g. roughness and DEM uncertainty; see Lewis et al, 2012), and projected future changes to the extreme water-level climate (see Karim and Mimura, 2008).…”

“…[8] A "1 in 50 year cyclone event" is the usual basis for flood risk modelling in this region (e.g. Jain et al, 2010b), and, as cyclone parameters are similar throughout the Bay of Bengal, the Sindhu and Unnikrishnan (2011) 50-year extreme ΔP estimate can be used (68.7 hPa) as the basis of an idealised cyclone event. Hence, by cascading observed variability within key cyclone parameters through the storm surge model, the storm surge uncertainty associated with this idealized 1 in 50 year cyclone event can be investigated.…”