Temporal and spatial variation of sediment risk in Turkey: the role of forestry activities and climate change scenarios (2022-2096) utilizing Entropy-based WASPAS and fuzzy clustering

The sustainable management of forestry activities, together with changes in vegetation due to deforestation or degradation, contributes to sediment risk and increases the risk of surface runoff. Changes in meteorological criteria, such as precipitation and temperature, as a result of global climate change are also significant factors affecting sediment risk. In this study, sediment risk was predicted spatially and temporally for 65 provinces in Turkey using criteria related to average forest road construction rates and average wood harvesting rates for the period between 2017 and 2021, as well as climate change models (GFDL-ESM2M, HadGEM2-ES, and MPI-ESM-MR) and their scenarios (RCP 4.5 and RCP 8.5) for five-year periods between 2022 and 2096. In addition, changes in sediment risk in the short and long terms-that is, trends-were determined in spatially and temporally. Entropy-based WASPAS and fuzzy clustering analysis were used together to determine sediment risk in this context. The results show that, in terms of sediment risk, criteria related to forestry activities had a higher weight than criteria related to climate change when looking at the overall criterion weights. In addition, it was generally observed that the contribution of the average precipitation criterion to sediment risk increased in weight over five-year periods in the context of climate change models and scenarios. Regarding climate change models and scenarios, it was found that provinces consistently in the highest risk category (R1) over five-year periods were mainly located in the Black Sea and Marmara regions. In addition, provinces showing an increase or decrease in sediment risk trends between two consecutive five-year periods were mostly found in the Black Sea and Mediterranean regions. When evaluating the 15-year time intervals, differences in sediment risk trends were found between the geographical regions. In conclusion, the study results indicate that, regionally, Turkey's northern regions, especially the Black Sea and Marmara regions, as well as the southern Mediterranean and western Aegean regions, will become increasingly vulnerable to sediment risk over time owing to the impact of climate change.