Abstract:
Mainstreaming coastal biodiversity certainly brings nature-based solutions for the conservation of
offshore and onshore resources. Being an island, the long-term shoreline change of Sri Lanka is
particularly important for management of the island’s coastal resources. This study was carried out at
the southwestern and southern coasts of Sri Lanka to investigate the protective capacity of mangroves
against coastal erosion, and coastal inundation hazards due to the climate associated sea-level rise.
Structural diversity of mangrove stands was assessed in terms of alpha-diversity, plant species richness,
basal area, tree height, density, and structural complexity index. Analysis of aerial photographs and the
ASTER Global Digital Elevation Model was used to identify shoreline changes along the southwestern
and the southern coasts of Sri Lanka. Results revealed that by and large, the southwestern coast is
highly vulnerable to coastal erosion and inundation hazards whereas the southern coast manifests
a tendency to retreat. The average annual rate of shoreline change however varies within the two
coastal areas, as there were accreting as well as eroding segments on both southern and southwestern
coasts, nevertheless, all retreating beach segments were the sites of improper maritime developments.
Segments with lower rates of shoreline erosion and coastal inundation hazards were found to be
located close to the mangrove and other coastal vegetation with varying structural complexity and
diversity. Reforestation and restoration of vegetation in coastal lagoons and estuarine habitats are
evidently effective strategies not only to protect the low-lying coastal hinterlands but also to preserve
coastal biodiversity.
