Comprehensive evaluation of coal mine pit lake hydrological connectivity in South Kalimantan, Indonesia

Abstract

Abstract This study presents the first comprehensive evaluation of an ex-coal mine pit lake at a landscape scale in Indonesia, using a hydrological connectivity approach. The stability of the water balance and water quality of a pit lake depends on the condition of the catchment area, which functions as a source of water inflow. To assess this, a combination of Remote Sensing (RS) and Global Information Systems (GIS) techniques, along with field surveys e.g., bathymetric, and hydraulic survey, infiltration rate testing, and soil sampling for geochemical analysis, was used. The study focused on the Paringin pit lake, situated in a rehabilitated catchment area, and its hydrological connections from upstream to downstream in which the lake plays important hydrological function. The evaluation of Paringin pit lake catchment area resulted in the first Normalized Difference Vegetation Index (NDVI) map for the land cover assessment of the pit lake's catchment area in Indonesia. It is concluded that with the proportion of the pit lake and good catchment area being 1:7 in a tropical climate with rainfall of more than 3,000 mm/year and evaporation of 1,000 mm/year, the lake will become a flow-through lake with good water quality.