Effects of climate change on water resources of the Büyük Menderes river basin, western Turkey

Authors: ÖMER FARUK DURDU

Abstract: Temperature and rainfall changes are both significant components of climate change. This study characterizes the effects of climate change on water resources in the Büyük Menderes river basin in western Turkey, based on hydrology, temperature, and rainfall data from the past 45 years (1963-2007). When analyzed with the Mann-Whitney test, the temperature and precipitation time series exhibited obvious step changes with a 5% level of significance. Both the parametric t-test and nonparametric Mann-Kendall statistical test results showed an increasing trend of the temperature. Over the past 45 years, the temperature increased just about 1 °C. The long-term trend of annual precipitation demonstrated a decreasing trend; however, it was not found to be statistically significant. The spatial distribution of the precipitation pattern showed that the precipitation amount had an increasing trend in the 1970s, especially in the Aydın region, with a value of 5.8%. The precipitation amount started to decrease in the 1980s, especially in the Afyon and Uşak regions, with a value of -6.8%. Serious water scarcity began to appear in the 1990s, especially in the Aydın region, with a value of -14.4%. The streamflow of the Çine and Akçay rivers showed a decreasing trend, especially during the period of 1985-1998. The decreasing trend of the streamflow in the tributaries had a strong correlation with changes in temperature and precipitation. An increasing trend in temperature and decreasing trends in precipitation and streamflow in the Büyük Menderes river basin may be interpreted as climate change.

Keywords: Climate change, water resources, Büyük Menderes basin

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