Case study of the Agacli landslide–gully complex during post-coal-mining reclamation and afforestation

The concept of sustainable development has gained wide acceptance in the fields of mining and environmental studies. Mining is a temporary activity, but its impact on the environment persists long after mine closure. The aim of this research is to investigate the effect of land-use change on the stability of the Agacli landslide, northern coastal part of the Istanbul (Turkey), spanning periods of mining, reclamation, and afforestation. Geological and geophysical surveys were performed to determine the effects of erosion on the landslide. To assess the possibility of water responsible for triggering a landslide–gully complex, the dynamic elastic parameters of the field are calculated. Field observations indicate that surface erosion and gully development have ceased in the afforested area; however, gullies in non-forested areas continue to increase in size and depth. Uncontrolled surface water and water from stock watering ponds have trigger erosion and rapid sedimentation of the landslide–gully complex, resulting in over-steepening and enhanced landslide activity on the flanks of the main slide.