Wave climate projections along the Indian coast

Abstract

Future changes in wave climate will influence the marine ecosystem, coastal erosion, design of coastal defences, operation of near-and off-shore structures, and coastal zone management policies and may further add to the potential vulnerabilities of coastal regions to projected sea level rise. Many studies have reported changes in the global wave characteristics under climate change scenarios, but it is important to project future changes in local/regional wave climate for smooth implementation of policies and preventing severe coastal erosion and flooding. In this study the regional wave climate along the Indian coast for two time slices, 2011-2040 and 2041-2070, is reported using an ensemble of near-surface winds generated by four different CMIP5 general circulation models (GCMs), under RCP4.5 scenario. Comparison of the wave climate for the two time slices shows an increase in wave heights and periods along much of the Indian coast, with the maximum wave heights increasing by more than 30% in some locations. An important finding is that at most locations along the east coast, wave periods are expected to increase by almost 20%, whereas along the west coast an increase of around 10% is expected. This will alter the distribution of wave energy at the shoreline through changes in wave refraction and diffraction, with potential implications for the performance and design of coastal structures and swash-aligned beaches. Furthermore, the computations show material changes in the directional distribution of waves. This is particularly important in determining the longshore transport of sediments and can lead to realignment of drift-aligned beaches, manifesting itself as erosion and/or siltation problems. This study is a preliminary contribution towards regional climate projections for the Indian Ocean region which are needed to plan and mitigate the impacts of future climate change. K E Y W O R D S climate change, coastal vulnerability, dynamical projections, Indian coast, surface ocean waves, wave climate variability

Effect of long-term wave climate variability on performance-based design of coastal structures

“…But, to project future waves, future wind condition information is necessary. In this approach, winds derived from general circulation models (GCMs) or regional climate models (RCMs) are used to force a wave model (Chowdhury et al, 2019).…”

Shoreline modelling on timescales of days to decades

“…Global climate change is expected to result in geographically widespread differences in; storm frequency and intensity (Dorland et al, 1999; wave climate variability (Castelle et al, 2018, Chowdhury et al, 2019, Meucci et al, 2020, Morim et al, 2018, Morim et al, 2019; rising sea levels (Nicholls et al, 2014, Fox-Kemper et al, 2021 and significant morphological changes and impacts to vulnerable coastlines (Wiggins et al, 2019, Enríquez et al, 2017, Vousdoukas et al, 2020. The common assumption that the morphology remains unchanged during sea level rise is inaccurate for projecting coastal evolution on decadal and climate change timescales (Anderson et al, 2018b).…”

Regional wave climate projections forced by EURO‐CORDEX winds for the Black Sea and Sea of Azov towards the end of the 21st century

“…The number of future wave projections using CMIP6 GCM wind fields is very few on a global scale (e.g., Kumar et al, 2022; Song et al, 2020), and, as of August 2022, regional wave climate projections (e.g., Alizadeh et al, 2022; Krishnan & Bhaskaran, 2020; Liu et al, 2022) are still relying on low‐resolution GCMs, given the absence of forcing CMIP6 RCM outputs. Many studies (e.g., Bricheno & Wolf, 2018; Chowdhury et al, 2019; Erikson et al, 2015; Wang et al, 2014) present regional wave climate projections using high‐resolution CORDEX RCMs downscaled from CMIP5 GCMs and some studies use statistical downscaling methods to increase GCMs resolution (e.g., Camus et al, 2017; Perez et al, 2015). Although regional projections can be produced using directly low‐resolution GCMs (Gallagher et al, 2016), the uncertainties increase when the wave model is forced with lower‐resolution wind fields.…”