Estimation of flood extent maps by taking into account the impact of climate and land use changes in Değirmendere Basin

In this study, considering the effects of climate and land use changes, the possible floods and maps of these floods downstream of Değirmendere Basin located in the south of Trabzon Province in the Eastern Black Sea Basin of Turkey, which is subject to major floods, were estimated. The most appropriate distribution for the annual maximum flows of the Stream Gauge Station (AGI) on Değirmendere Basin was determined, flood flows (QT) with 100, 200, 500 and 1000 yearly return periods were estimated according to this distribution and a relationship between QT/Qmean values and the probability of non-exceedance (F) was obtained. The equation obtained between QT/Qmean and F for Değirmendere Basin and the average flows (Qmean) and various return period discharges (QT) for the years of 2040, 2070 and 2100, considering climate change, were estimated. The stream hydrograph of the basin for the years 2040 and 2070 and 2100 was estimated by using 100 and 200 and 500 and 1000 yearly return periods estimated flood discharges. With the help of 2000 and 2023 satellite images, land use maps for the years 2040, 2070 and 2100 were estimated. Then, using the hydrograph and land use values, flood parameters (extent, water depth, mean water velocity, depth*velocity and arrival time) that are effective on flood damages were estimated for the determined return periods and years, and the changes of these parameters were analyzed and mapped. As a result, it was concluded that as the flood return period increases and the years progress, there will be a decrease in arrival time and an increase in other parameters.