Monitoring Mining Impact for Geosites Using Time Series NDVI and Run-off in the Eastern Part of Southern Java Mountains, Indonesia

Several geosites in the Eastern Part of the Southern Mountains of Java which are currently being mined are important geosites because they have recorded tectonic processes in the tertiary period. However, mining activities without environmental monitoring could be  lead loss of rock outcrops and alteration of mineralscontained in the geosite. This study aims to monitor the vegetation index and run off in karst geosites and gold mined hills. We used Sentinel 2A Imagery on the Google Earth Engine (GEE) to get the vegetation index (NDVI) and run off values temporally. The Sentinel 2A data acquisition pro-cess in both 2018 and 2022 was carried out on the Google Earth Engine with specific steps consisting import data from cloud collection, cloud masking, and customing date acquistion. The results show that there has been a decrease in the vegetation index in the period 2018-2022 which is indicated by the decrease in the vegetation index value in the mined area. Another impact found is that there has been an increase in the run-off value in 2022 in both the Karst Puger Hills and the Tumpang Pitu Hills. The NDVI pattern on mined geosites has also changed significantly due to increasingly intense mining activities. The NDVI fluctuation pattern in the Karst Hills in 2018-2020 ranges from 0.41 to 0.74, while in 2021-2022 the fluctuation pattern is only in the range 0.05 to 0.4, respectively. The NDVI fluctuation pattern in the Tumpang Pitu Gold Hills in 2018-2019 is in the range 0.6 to 0.8, while in 2020-2022 it is in the range 0.38 to 0.52, respectively. Google Earth Engine is able to map the vegeta-tion index more efficiently by using a time series approach. These advancement is different compare to previous studies, where our study shows rapid acquisition during pre-processing, performing NDVI with rapid temporal analysis, and shows numerous degraded land in southern java mountains.   There-fore, it can be concluded that there has been a decrease in the vegetation index and an increase in run off which can threaten the rock outcrop on the geosite. Furthermore, this study suggest that GEE should be considered as a main tool to identified degraded land, particularly for geosite conservation.