Effects of soil erosion on doline lake degradation within karst landscapes: Bakkal Lake, Turkey.

Gypsiferous soils in karstic landscapes are important areas in terms of biodiversity and geology. One of the geological formations occurring in gypsum regions is the doline lakes. Subsidence dolines must be preserved because of their formation and fossil heritage. Erosion is one of the most serious types of degradation among these types of lakes. The Bakkal Lake is one of the most important doline lake in central Turkey and is at risks with sediment flow. In this study, we aimed to determine how erosion poses a threat to the geological heritage in areas such as doline lakes and to simulate what measures can be taken to protect them. RUSLE/GIS/remote-sensing technologies were used to estimate the distribution and amount of sediment flowing into the lake. According to the results of the study, the amount of sediment transported to the lake was estimated to be 2.73tha-1y-1, and the total amount of sediment transported was 2876 m3y-1. The time until Bakkal Lake is filled with sediment flux was calculated to be 698 years. The simulation was developed by offering protection measures to reduce sediment flow to the lake. As a result of the simulation, it was calculated that the amount of sediment flowing into the lake decreased to 2.29 tha-1y-1 and the filling time increased to 833 years. The study showed that a doline lake, which under natural processes would not be filled for thousands of years, will soon be filled unless radical measures are not taken. This study asserts that more planners should use simulations to model sediment flow to better select appropriate conservation measures.