Study on the impact of coal mine land reclamation on watershed hydrological and ecological function and social economic aspects of the local community

Abstract

This research was conducted at the PT Adaro Indonesia coal mining area in Negara watershed, sub-watershed of Barito, South Kalimantan Province. The aims of the study were: 1) to identify of the methods used for coal mined land reclamation; 2) to analyze the impacts of the reclamation on the hydrological and ecological functions of the watershed; and 3) to analyze the impact of the land reclamation activities on the involvements of and benefits for the communities. This study was carried out using survey method and field measurements in identifying the methods of reclamation. Analyzis of watershed hydrological function showed that reclamation activities significantly increased soil infiltration rate from 0.27 cm/hr to 1.01 cm/hr, decreased runoff coefficient from 49.04% to 13.97% and decreased erosion rate from 130.28 ton/ha to 7.64 ton/ha. Biodiversity analysis showed that there was no significant impact of reclamation activities on biodiversity at the early stage of reclamation trees up to 6 years of its development. However, after the reclamation trees were at the age of 15 years, the biodiversity indexes increased significantly; shurb index increased up to 1,10, seedlings 0.76, saplings 0.85, poles 0.53, and trees 0.23. Carbon sequestration analysis showed that the reclamation activities increased carbon sequestration significantly. At the area where the reclamation trees were at 15 years old the carbon stock reached 103.57 ton/ha, which consist of 95.94 ton/ha at trees, 4.12 ton/ha at undergrowth, and 3.51 ton/ha at the litter. Analysis of the impact of reclamation on social-economic of the local communities showed that the income of labor increased substantially up to Rp 36,000,000 per year, the income that have been greater than the income that can support life worthed living standard (Rp 24,000,000/year). This income was also already greather than income of South Kalimantan GDP (195%) and national GDP (117%). Multiple benefits gained by the local communities during the reclamation activities among others were the opportunities for supplier of food and housing, compost and plant seeds; the post-mining benefits from timber and non timber product of reclamation; as well as benefits from infrastructure/roads and recreation facilities.