Temporal Change of Climatological Precipitation Deficit Index in Buyuk Menderes Basin,Turkey.

The spatial and temporal distribution of precipitation is irregular in Turkey, a semi-arid climate zone. Due to global climate change, drought is predicted to have a severe impact, especially in Mediterranean waters, and precipitation may decrease seriously in some regions of Turkey. Therefore, the examination of the drought phenomenon is an extremely important element for quality of sustainable life.
Climatological precipitation deficit index (PD) is one the indices used to monitor the agricultural drought by examining the difference between precipitation and evapotranspiration. In this study, the meteorological stations located in the Buyuk Menderes Basin, which has an important agricultural potential in Turkey, are used to determine the climatological precipitation deficit index and the temporal variation with Mann-Kendall trend analysis by using the monthly climate data of 1975-2014 period.

The long-term average rainfall in the Buyuk Menderes basin was 574 mm, the reference evapotranspiration was 1225 mm, and average PD value was 651 mm. It was observed that the value of precipitation deficit in the basin varies considerably over years. The trend analysis showed five of the six stations in the basin in increasing trend, with three of the five stations being statistically significant.