Climate change impacts assessment on snow hydrology and irrigation in Turkey

Climate is changing in a way that can not be explained by natural variability. One of the most affected areas by global warming is hydrology and water resources. Regions where majority of runoff consists of snow melt, which is an important water resource to many aspects of hydrology including water supply, flood control and erosion, are more sensitive to climate change, particularly temperature increases. Euphrates River located in the mountainous Eastern Anatolia in Turkey, is one of the major rivers within Middle Eastern countries. Euphrates Basin is the largest basin of Turkey and it has 17% of entire country’s water potential. Snow is the main water source of Euphrates Basin, particularly for headwater of Euphrates Basin, which is also called Karasu Basin. Despite the significance of Euphrates Basin, there are very limited hydrological modelling studies for this basin. Moreover, impacts of climate change on hydrology of Euphrates Basin have not received sufficient attention. One of the most snow dominated subbasin of Euphrates Basin, Karasu Basin, was selected as study area and climate change effects were investigated for this subbasin in this study. Firstly trend analysis of hydro-meteorological data was performed based on non-parametric trend tests for better understanding of historical trends and investigating climate change finger prints in Karasu Basin. Statistically significant warming trends were detected in particular since 1992. Then, historical flows were simulated by using two conventional hydrological models. In addition, Artificial Neural Networks based hydrological model was developed to simulate runoffs in Karasu Basin. Then, future climate data over period of 2070-2100 was preceded for Karasu Basin and projected outcomes of climate models were used in calibrated hydrological models to predict future streamflows of Karasu Basin for the purpose of having an idea on future water availability in the basin. Largest decreases in streamflows were detected for summer season due to larger temperature increases and precipitation decreases. Runoff decreases were modelled for all seasons except autumn season. Based on available data, impacts of climate change on water sectors in Karasu and Euphrates basin were discussed. Agriculture sector is the largest water consumer with 70% over the world and it has a direct relation with climate. Thus, it is among the most sensitive sectors to climate change. Although this study does not include any modelling study on agriculture and climate change relation, climate change impacts on agriculture and irrigation were explained in detail based on studies in the literature for different parts of the world and Turkey.