Abstract:
Global sea-level changes have been a major topic among scientists. Sea-level changes are not globally uniform.
Reconstruction of paleo sea-level changes and monitoring of variations in regional sea-level are important to (i)
evaluate future sea-level changes, and (ii) predict risk assessment. In this study, we examined sea-level inundation
during the middle Holocene highstands based on paleo sea-level indicators along the south and southwest coasts
of Sri Lanka. Besides, future sea-level inundation was predicted considering the calculated sea-level trends based on
tidal gauge data and high-resolution surface elevation data. Light Detection and Ranging (LiDAR) is one of the
most accurate optical remote sensing methods currently available to obtain high-resolution land surface elevation
data. Therefore, in this study, Digital Elevation Models (DEMs) were prepared using LiDAR data for estimating the
risk assessment in coastal lowlands. Tide gauge data of Colombo in Sri Lanka (from 2006 to 2017), Gan in the
Maldives (from 1995 to 2017), and Hulhule in the Maldives (from 1995 to 2017) showed that sea-level has increased
with a rate of 0.288 ± 0.118, 0.234 ± 0.025, and 0.368 ± 0.027 mm/month, respectively. DEMs based on LiDAR data
suggested that south and southwest coasts are a risk of future sea-level inundation (height = 0.1–0.2m during next
50 years and about 0.7m in height during next 200 years, and distance = about 3.5–15.0m from the present sealevel
towards the inland). Consequently, it is important to consider future sea-level changes in disaster
management and mitigation activities along the south and southwest coasts of Sri Lanka.
