Investigation of land-use changes in Western and Southern coasts of Sri  Lanka in the past two decades (1996-2016): A field based geo-informatics  approach 

Coastal region of Sri Lanka abounds with invaluable resources and provides varying ecological services bringing economic benefits to people. In contrast, dramatic land-use changes, which lead to degradation of the coastal zone, have been observed in recent years. In that sense, the western and southern coasts, in particular, had been facing severe threats.  Therefore, this study aimed at investigating current land-use/cover (LULC) changes in western and southern coastal belts of Sri Lanka (WSC-SL) over the period from 1996 to 2017, identifying reasons/causes for those changes and analyzing LULC changes to predict possible future trends. The study area, WSC-SL, is defined as the coastal belt that covers a  width of 2 km coastal strip from Kalpitiya in the western province to Yala in the southern province. LULC architecture is classified into seventeen classes, namely, aquaculture, bare lands, coconut plantation, forest, grassland and marsh, mangroves, paddy land, rubber plantation, tea plantation, other cultivations, saltpan, sandy areas, scrubland and chena, settlements, homesteads, water and other land-uses. LULC map for 2017 was prepared using on-screen digitization of Google earth images, which produced an 84.7% overall accuracy along with kappa, κ = 0.837 (indicates a near perfect agreement between the classified LULC map and ground truth data) and p < 0.01 (at 99% confidence interval). LULC changes from 1996 to 2017 were quantified with overlay analysis technique and reasons for changes were  investigated through personal communications and questionnaire surveys (1996 & 2007 LULC maps: ©Sri Lanka Survey Department). Area estimates for each LULC class in 1996, 2007 and 2017 were generated from available digital LULC maps and were subjected to trend analysis. All GIS work were carried out using ArcMap10.3. Significant changes (p