Geomatics for monitoring rehabilitation Status in Aruwakkalu Limestone Quarry, Sri Lanka

Abstract

Aruwakkalu limestone quarry in Sri Lanka, owned and operated by Siam City Cement (Lanka) Limited, is one of the largest limestone deposits in Sri Lanka. Since the limestone deposit is seated in a shallow depth, it is being excavated by utilising opencast mining methods. The target main product from the extracted limestone is to produce cement. As the first step of ehabilitation, the land restoration is carried out by backfilling the mined-out areas with the previously stripped overburden material. To achieve the final landform, replantation of vegetation cover is formed by planting native trees on top of the re-filled land area. This study aims to evaluate UAV suitability for monitoring rehabilitation in the Aruwakkalu limestone quarry, geomatics-based vegetation analysis in rehabilitated areas, and the assessment of the drainage system of the study area. Aerial images were acquired from an UAV equipped with a multispectral sensor and the data was post processed by utilising Pix4D, ENVI, and ArcGIS software. The processed data was classified into different regions according to the rehabilitated year and further analyses revealed that there were certain areas which had poor vegetation cover which requires revegetation measures. Analyses of the terrain models of the study area revealed irregular drainage patterns, which need to be rectified by grading and forming better landforms. The findings provide valuable insights for monitoring and improving rehabilitation efforts in similar mining sites, contributing to sustainable mining operations.