Tide-rainfall flood quotient: an incisive measure of comprehending a region’s response to storm-tide and pluvial flooding

Abstract

It is undeniable that coastal regions worldwide are facing unprecedented damages from catastrophic floods attributable to storm-tide (tidal) and extreme rainfall (pluvial). For flood-risk assessment, although recognizing compound impact of these drivers is a conventional practice, the marginal/individual impacts cannot be overlooked. In this letter, we propose a new measure, Tide-Rainfall Flood Quotient (TRFQ), to quantify the driver-specific flood potential of a coastal region arising from storm-tide or rainfall. A set of inundation and hazard maps are derived through a series of numerical and hydrodynamic flood model simulations comprising of design rainfall and design storm-tide. These experiments are demonstrated on three different geographically diverse flood-affected coastal regions in India. The new measure throws light on existing knowledge gaps on the propensity of coastal flooding induced by the marginal/individual contribution of storm-tide and rainfall. It shall prove useful in rationalizing long-term flood management strategies customizable for storm-tide and pluvial dominated global coastal regions.

Guidelines for Studying Diverse Types of Compound Weather and Climate Events

“…This can affect model accuracy under climate change, when information needs to be extrapolated far beyond the observed range. High‐resolution hydrodynamic models , which include the non‐linear interaction between hydraulic processes, topography, and human interventions (Kumbier et al., 2018; Mohanty et al., 2020; Wu et al., 2021), can provide a valid alternative for a thorough CF analysis. Hydrodynamic modeling can provide a detailed spatial mapping of water levels in the estuary, for example, it can be used to quantify the relative contribution of flood drivers (Mohanty et al., 2020) and the spatial variability of socio‐economic impacts of flooding depending on the level of urbanization within the estuary, which can influence runoff characteristics (Olbert et al., 2017; Sebastian et al., 2019).…”

“…High‐resolution hydrodynamic models , which include the non‐linear interaction between hydraulic processes, topography, and human interventions (Kumbier et al., 2018; Mohanty et al., 2020; Wu et al., 2021), can provide a valid alternative for a thorough CF analysis. Hydrodynamic modeling can provide a detailed spatial mapping of water levels in the estuary, for example, it can be used to quantify the relative contribution of flood drivers (Mohanty et al., 2020) and the spatial variability of socio‐economic impacts of flooding depending on the level of urbanization within the estuary, which can influence runoff characteristics (Olbert et al., 2017; Sebastian et al., 2019). Furthermore, hydrodynamic simulations can highlight peculiar features of the hydrological system (Khojasteh et al., 2021), for example, directly accounting for a potential shift in the area affected by compound effects from future sea‐level rise (Bilskie & Hagen, 2018; Helaire et al., 2020).…”

Projected Changes in Compound Flood Hazard From Riverine and Coastal Floods in Northwestern Europe

“…A number of studies, at local to continental scales across Europe (Bevacqua et al, 2019; Ganguli & Merz, 2019a, 2019b; Kew et al, 2013; Klerk et al, 2015; Petroliagkis, 2018; Svensson & Jones, 2002), the United States (Moftakhari et al, 2017, 2019), Australia (Zheng et al, 2014), China (Lian et al, 2013; Tu et al, 2018), India (Mohanty et al, 2020), Bangladesh (Ikeuchi et al, 2017), and the entire globe (Couasnon et al, 2020; Eilander et al, 2020; Ward et al, 2018) have analyzed compound effects of high coastal water levels (or storm surges and/or tides) and river discharges (or extreme precipitation as proxy for river discharge). Challenges to compound flood hazard assessment at a large scale under projected climate involve precisely estimating the interaction between the various drivers given the uncertainty of Earth system models (Deser et al, 2020).…”

Guidelines for studying diverse types of compound weather and climate events

“…This can affect model accuracy under climate change, when information needs to be extrapolated far beyond the observed range. High-resolution hydrodynamic models, which include the non-linear interaction between hydraulic processes, topography, and human interventions (Kumbier et al, 2018;Mohanty et al, 2020;Wu et al, 2021), can provide a valid alternative for a thorough CF analysis. Hydrodynamic modeling can provide a detailed spatial mapping of water levels in the estuary, for example, it can be used to quantify the relative contribution of flood drivers (Mohanty et al, 2020) and the spatial variability of socio-economic impacts of flooding depending on the level of urbanization within the estuary, which can influence runoff characteristics (Olbert et al, 2017;Sebastian et al, 2019).…”