Flood and gully erosion problems at the Pasir open pit coal mine, Indonesia: a case study of the hydrology using GIS

This paper considers the flood and gully erosion problems at the Pasir open pit coal mine located in a humid region in Indonesia. Using the geographic information systems (GIS), quantitative information on the hydrological characteristics of the surface drainage system were obtained from a digital elevation model (DEM). Based on the results of the drainage analysis, raster-based spatial analysis was carried out to distinguish the bench slopes with concentrated surface drainage flows and to calculate the ratio between the amount of incoming water and the size of the temporary storage ponds. Finally, the bench slopes most vulnerable to gully erosion were identified and an optimal design for pump allocation suggested to reduce the risk of flooding during heavy rainfall. Since these recommendations were implemented, there has been no down-time due to flooding.