Deforestation or Reforestation, A Time Series Remote Sensing Perspective of Wilpattu National Park, Sri Lanka

Abstract

National parks by far could be considered as the heart of a countries bio network. This study attempts to identify and analyze the forest cover and its changes in the Wilpattu national park of Sri Lanka, which has grown into a level of a national crisis. The rapid utilization of remote sensing satellites and techniques has provided a reliable and near real time possibilities to characterize terrestrial ecosystem properties. In this study a series of Landsat imagery ranging from the year 1975 to 2015 have been used for the analysis. Initially, Support vector machine (SVM) based land cover classification was performed for all the images and the changes in the forest class was determined. Secondly Vegetation indices Normalize Difference Vegetation Index (NDVI), Normalize Difference Water Index (NDWI) Green Normalize Difference Vegetation Index (GNDVI) were used to separately extract the Vegetation, surface water and canopy conditions respectively. Deforestation rate was calculated based on definitions from FAO (Food and Agriculture Organization). The study found out that there is a reforestation inside the national park (annual reforestation rate of 0.17%), while deforestation outside close to the boundaries of it (annual deforestation rate of -0.29%).