Camargo, F, Zamora, G & Janampa, C 2025, 'Implementation of a methodology to evaluate and optimise closure measures at a coal mining operation in northern Colombia', in S Knutsson, AB Fourie & M Tibbett (eds), Mine Closure 2025: Proceedings of the 18th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-16, https://doi.org/10.36487/ACG_repo/2515_84 (https://papers.acg.uwa.edu.au/p/2515_84_Camargo/) Abstract: The study was conducted at a thermal coal project located in northern Colombia in one of the largest open pit coal mines in the world. The objective of the study was to evaluate the erosion rates in the waste dumps by implementing erosion plots combined with a rainfall simulation system. This system modelled different precipitation intensities based on the hydrological conditions of the site. Through this simulation, sediment volumes generated under different vegetation cover conditions were obtained to define closure measures for landscape rehabilitation. The activities carried out included the hydrological analysis of the study area, the design and installation of the rainfall simulation equipment, the creation of the erosion plots (including their instrumentation and the required hydraulic structures), the definition of the vegetation cover to be analysed and the execution of the corresponding tests. This study provided valuable information for decision-making in the design of erosion control measures and optimisation of waste dump management strategies in the mine closure plan. Furthermore, the results revealed differences in erosion rates depending on the vegetation cover studied, as well as the positive influence of vegetation cover in reducing erosion. Analysis of the data generated allowed relationships to be established between rainfall intensity and the effectiveness of the cover implemented. The erosion rate data will be used to calibrate and develop a land evolution model that will allow future evaluation of landforms with and without erosion control measures. In addition, the work performed is the first step in a series of analyses that the mine owner intends to develop to assess other variables such as vegetation type, plowing methods, and water and sediment management structures that could result in more efficient and economically viable closure measures. This project contributes to the knowledge of land management and rehabilitation in tropical open pit mines and is a step towards sustainable mine closure in the country of Colombia. Keywords: erosion rate, simulation, erosion plots, waste dump, closure measure