Abstract:
Sea level rise is a profound indicator for circumstance of human activities relatively growing
population and their requirements of the development during last three decades. The coastal area
around the country consisted of most dense population, economically active land areas and
interconnected infrastructures such as ports, fisheries harbours, industries, express roads and port
cities. One of leading impacts of global warming is a progressive rise of mean sea level by the causing
of thermal expansion of oceanic water and melting of glaciers. Sea level records were collected from
Sri Lankan tide gauge network and 10 sampling stations from gridded satellite sea level observations
during last 25 years around the country. The satellite data was provided by the Achieving Validating,
Interpretation of Satellite Oceanography (AVISO). The high frequency tide gauge time series data were
averaged to obtained monthly mean and was superimposed on the same axis of satellite time series
mean sea level to compare the precision of expected sea level trend. The vulnerable coastal area was
calculated under three ranking based on elevation factor from the mean sea level zero to 3m elevation
in 1m contour using the Shuttle Radar Topographic Mission (SRTM) 90 m Digital Elevation Map
(DEM) originally produced by the NASA with horizontal datum WGS84 and Vertical datum EGM96
using Arc Map 10.1. Satellite derived annual average mean sea level trend 2.585mm around the
country while tide gauge estimated trend 2.904mm were showed with a difference of 0.319mm positive
deviation from satellite observations. The sea level trend in northern coast little lower than southern
coast around of the country. The tide gauge observations showed root mean square differences
(RMSDs) approximately 80% of the variance of the MSL signal estimated from satellite altimetry data.
Annual variation was 20 to 30 cm according to the average monthly mean sea level signals during the
last 25 years. The enumerated vulnerable land area were classified as highly vulnerable, moderately
vulnerable and low vulnerable with the elevation gradient of 0-10 cm, 10-20 cm, 20-30 cm. The
maximum vulnerable land area was recorded in the Northern part of the country within 100 Sq.km of
land area below 1m elevation exposing to the ocean based hazards induced by sea level rise.
