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Future coastline recession and beach loss in Sri Lanka

Bakker, P.J.J. (2018) Future coastline recession and beach loss in Sri Lanka.

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Abstract:Amongst accelerating trends, the response of coastlines to sea-level rise is of major importance to policy makers. This research aims to provides a nation-wide overview of short-term (2050) and long-term (2100) coastline recession and beach loss along the Sri Lankan coast. Coastline recession estimates have been acquired using the original formulation of the first-pass assessment method for sea-level rise induced coastal erosion known as the Bruun rule, nearshore bathymetry measurements, and mean and likely climate change predictions according to the four Representative Concentration Pathways (RCPs) in the Fifth Assessment Report published by the Intergovernmental Panel on Climate Change. Additionally, future coastline recession at beaches downdrift from several important rivers, and large coastal lakes and lagoons have been assessed using the (reduced) Scale-aggregated Model for Inlet-interrupted Coastlines, and the BQART model determining annual fluvial sediment supplies combined with a sediment trapping efficiency protocol for nested reservoirs. The nation-wide averaged (representing 48% of the Sri Lankan coast) mean sea-level rise induced long-term coastline recession is 16 m (RCP2.6), 21 m (RCP4.5), 23 m (RCP6.0) or 31 m (RCP8.5). However, significant regional (e.g. South-east vs North-east) in the coastline recession estimates are present. Combined with present beach widths measured from satellite data, the mean Bruun rule coastline recession estimates show considerably reduced future beach widths and the possible disappearance of a vast number of beaches along most of the Sri Lankan coast. Downdrift from East and North-east coast lagoons that are open or intermittently closed to the ocean, sea-level rise will result in mild to (dangerously) strong local coastline recession. The presence of lagoons in the Jaffna Peninsula is expected to result in local coastline progradation. Projected changes to the terrestrial climate and continuing human development of river catchments will result in increased annual fluvial sediment supplies. However, without limits to future river mining activities, local coastline recessions remain a possibility.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
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