Vulnerability assessment of islands from the impacts of SLR

Vulnerability Assessment of Islands from the Impacts of SLR

/ Research / In-House /IIM/ Vulnerability Assessment of Islands from the Impacts of SLR

The Project

Climate change is the most complex and challenging environmental problem confronted by the world today. The low-lying coastal areas around the world are threatened by climate change-related hazards. According to IPCC Fourth Assessment Report (2007), small islands territories are the most vulnerable to climate variability and long-term climate change impacts. Indian Islands (Andaman and Nicobar and Lakshadweep islands) are highly vulnerable to climate change, not only because of high physical exposure to climate-related disasters but also because of the dependency of its economy and majority of the population on climate-sensitive sectors such as agriculture, forests, fisheries, tourism, animal husbandry, and fisheries. The Indian islands are having a good scenic beauty, are rich in flora & fauna diversity, medicinal plants, and have huge tourism potential. But these islands are susceptible to erosion, subsidence, inundation due to storm surge and saltwater intrusion, thereby threatening the existing infrastructure, property, agricultural fields and loss of life. These islands can be protected by providing technical support in building a community of practice, and thus achieve predictable and long-term sustainable development plans to ensure their resilience. The present study demonstrates vulnerability assessment into two different approaches 1. GIS-based inundation model & 2. Coastal Vulnerability Index (CVI).

Keywords

Climatic change

Sea level rise

Coastal vulnerability

Andaman and Nicobar Islands

GIS

Remote Sensing

Objectives

Assess the current vulnerability of climatic change due to SLR on the coastal ecosystem of the islands.
Assess the future SLR risk using RCP scenarios (RCP 2.6, 4.5, 6.0 & 8.5).
Prepare an Integrated coastal vulnerability map for islands.
Develop a policy framework for adaptation/mitigation strategy for islands

Key Findings

Case study 1: Impact of sea-level rise and shoreline changes in the tropical island ecosystem of Andaman and Nicobar region – A case study of Little Andaman island

The most obvious effect of sea-level rise is the permanent inundation of seawater in the low-lying coastal areas. In the present study, we assessed and estimated the impacts of projected SLR on Land use/land cover by overlaying different inundation scenarios generated from the digital elevation model (DEM). Further, assessment of shoreline change is also made for the short-term and long-term periods using DSAS.

Inundation due to projected sea-level rise scenarios

(a) Short-term Shoreline change (b) long-term Shoreline change

Statistics of shoreline change in the different period

The study estimated that if the SLR is by 1 m from the current level, the inundation shall submerge a total area of 1042 ha, and for a 3 m and 5 m rise, the inundation will cover an area of 2049 ha and 3077 ha respectively.
Forest cover close to the coastal tracks of Little Andaman is most susceptible to the impact of SLR with a maximum damage of 2912 ha, followed by settlement with vegetation (72.3 ha), plantation (29.19 ha) and scrubland (23 ha) due to a 5 m rise in sea level.
From the short-term shoreline change analysis (2004-2005), it is inferred that the tectonic activity that happened during 26^th December 2004 resulted in the accretion in the western side of Little Andaman due to the upliftment of land in the north and western side.
From the long-term shoreline changes assessment (1976-2018) by the LRR method, accretion is dominated (58.3%) in the study region, followed by erosion (12.9%) and stable coast (28.8%).

Case study 2: Coastal vulnerability assessment to South Andaman Island using the geospatial approach

Assessing the vulnerability to climatic change is essential for identifying and recognizing the coastal livelihood, socio-economic and ecological security status. However, coastal vulnerability assessments require a complex dataset including human and socio-economic factors. In the present study, we used seven physical parameters (tidal range, significant wave height, sea-level rise, elevation, coastal slope, seismicity, tsunami) and four social parameters (population, road network, land use/land cover and tourism) to calculate the CVI to South Andaman Island.

Cumulative Vulnerability Index

The CVI for South Andaman is assessed for a 163 km stretch. The study estimated that around 30.3% of the coastal stretch comes under high vulnerability, followed by low vulnerability (27.3%), moderate vulnerability (25.4%), very high (9.2%) and very low category (7.6%).
The coastal sectors with a gentle slope, large tourism activities, high population density and high concentration of human activities resulted in the very high CVI. Whereas the region’s characteristics with high relief, cliffy coast with the absence of population, tourism activities and the non-urbanized region comes under very low vulnerable category.
The study demonstrates that South Andaman island is vulnerable to sea-level rise and climatic change-related hazards. Further, it also implies that a suitable coastal zone management plan has to be prepared in considering the climatic change-related hazard.