Abstract

Forest degradation is a serious problem that requires the implementation of efficient management techniques to stop deforestation and safeguard the ecosystems worldwide. Even Sri Lanka faces the difficulties of managing its forest resources in every part of the country. The Hirikatu Oya sub-watershed, which is a very important water source area, is located in the Imbulpe Divisional Secretariat Division (DSD) in Sabaragamuwa Province. In recent years, this area has been affected by issues related to forest degradation, highlighting the need for immediate action. The objective of this study is to examine the status of forest degradation in the Hirikatu Oya sub-watershed from 2000 to 2022. A mixed-method strategy is used to accomplish this purpose. Supervised classification maps and NDVI-based data from Landsat 7 & 8 were used to evaluate and analyse the changes in the forest cover and the effects of human activities. According to the canopy cover change analysis, NDVI, field observations and interviews, severe forest degradation was observed in the Hirikatu Oya sub-watershed between 2000 and 2010. The canopy cover decline was 8.29%, which was mostly attributed to human-caused activities such as encroachments and illicit logging. From 2010 to 2022, forest fires, tree felling, changes to agricultural lands, and mining issues emphasise the urgent requirement for efficient management approaches to deal with forest degradation in the area. Ongoing efforts to reinforce management strategies, enforce pertinent regulations and implement targeted programmes, are needed to reduce the spread of invasive plant species as well as to encourage sustainable forest management in the sub-watershed.

Keywords: Canopy cover, Forest degradation, GIS, NDVI, Sub-Watershed