An Assessment of Wave Climate Variability Using Energy Flux Method: A Case Study in the Coastal Area of Negombo to Wadduwa

Abstract

Wave climate can be described as the distribution of wave characteristics averaged over a period of time and for a particular location. Coastal erosion has significant impact from the change of wave climate. The West coast of Sri Lanka is identified as a severely eroding coastline according to the Master Plan for Coast Erosion Management in 2006. This study quantifies the wave climate variability in the West coast of Sri Lanka using ECMWF (European Centre for Medium-Range Weather Forecasts) wave data, in particular, ERA 5 collected over the years from 1979 – 2019. The occurrence of wave classes in the study area and the temporal changes in the wave parameters such as significant wave height, wave period, wind speed and sea surface temperature were analysed. Then significant change in long-term wave climate variability (1979-2019) and short-term wave climate variability (2010-2019), and the variation of wave energy in the study area were assessed. The significant increment has been happened in occurrences of wave classes and the wave parameters of the study area within the short term of period. Results of wave energy computations clearly indicate increase in the residual changes of wave energy flux in the short-term period during the Southwest monsoon. In addition, the occurrence of wave heights events which are greater than 2m have increased during the short-term of period than in long-term period. The changes in wave parameters and subsequently the coastal retreats in study area and possible measures are discussed in the paper.