Disentangling natural and anthropogenic drivers of karst flooding: multi-sensor analysis of the Gembos, Eynif, and Sobuca poljes (Taurus Mountains, Southern Türkiye)

Abstract

Karst poljes are highly sensitive environments where natural hydro-meteorological extremes and human landscape alterations often collide. In February 2026, the Gembos, Eynif and Sobuca poljes in the Taurus Mountains experienced catastrophic flooding. To understand the driving mechanisms behind this disaster, we investigated the combined roles of extreme precipitation, sinkhole (ponor) blockage, and local engineering failures. By establishing a 10-year climatological baseline and utilizing multi-sensor satellite imagery (Sentinel-1 SAR and Sentinel-2 NDWI) within a GIS environment, we mapped the spatiotemporal evolution of the flood to isolate anthropogenic impacts. Our comparative multi-year analysis revealed that the basins successfully managed higher precipitation loads during the snow-dominated winter seasons of 2019 and 2022. However, in 2026, intense heavy rain created an abrupt volumetric shock. A targeted spatial bottleneck analysis demonstrated that the newly inaugurated D687 highway embankment effectively acted as a significant amplifying factor against this rapid runoff. This barrier severely disrupted the natural surface flow, trapped the floodwaters, and triggered a catastrophic tenfold expansion of the inundated area, ultimately causing the complete submersion of the highway itself. Furthermore, field observations confirmed that sediment and debris, exacerbated by upstream quarrying activities, physically clogged the ponors and crippled the karst system’s vertical drainage capacity. This cascading failure highlights a crucial lesson: treating active karst poljes as standard topographic basins during infrastructure planning inevitably leads to disaster. Our findings underscore the critical need for spatial planning that respects natural karst hydrodynamics, supported by continuous monitoring networks.