Sea level variability in the east coast of Male, Maldives

Abstract

This paper discusses the variation of sea level with different time intervals in the East coast of Male, Maldives. Sea level is the mean water level, at which the oceans exist when averaged between high and low tides which is associated with many kinds of forcing agents in the sea caused by astronomical and hydrological forces. Estimated average annual global mean sea level rise was 2.8 to 3.6 mm yr-1. Volume of ocean was increased causing warming of the ocean, loss of glaciers and ice sheets, and reduction of liquid water storage on land (Intergovernmental Panel on Climate Change 5th Assessment report 2013). Sea level variation can be classified according to the time scale in which variability occurs from hours to hundreds of years such as seiches, tsunami, tides, storm surges, continental shelf waves, annual, inter-annual and sea level rise. Such variations under temporal dimension consist as hours, days, weeks, and months, seasonal, annual and inter-annual while spatial dimension can be classified as meso-scale, synoptic, global scale followed by local, regional and global scale respectively. The trend of mean sea level variation inferred from altimetry in Northern Indian Ocean (NIO) is 5±0.4 mm/year for the period of 1993-2012 (Indika et al., 2016). Sea level changes related to density change of specific volume due to change of temperature and salinity is caused by seasonal changes in precipitation, evaporation and heat fluxes which referred to steric height variability (Tomczak and Godfrey, 1994). The seasonal sea level range around the lower part of the northern Indian Ocean waters is about 0.2-0.3 m responding to the fresh water inflow, heat flux and other factors that are linked to climate change processes (Wijeratne and Pattiarachchi, 2006, 2011). Meanwhile some extreme variations are governed by sudden changes of atmospheric conditions in disturbed weather systems such as Meteotsunami. Exploration of Sea level dynamic is important for future challenges induced with global change to sustainable use of the ocean resources for navigation, harvesting of ocean recourses and coastal development planning for Maldives as an Island country.