Hydroclimatological and time-series analysis of variations in precipitation and aridity index series of the Akhisar and Manisa districts and geographical synthesis of their consequences with respect to desertification

This study performed a detailed analysis of climate and hydro-climatologic characteristics along with climate change and variability of the Akhisar and Manisa districts in order to climatologically determine nature and degree of observed increasing water scarcity and desertification processes over the Akhisar and Manisa plains during the period of about last 30 years. In the study, the data of stations having the long term climatic series of observations have been made use of. The stations chosen for the study consist of Manisa, Salihli, Turgutlu and Akhisar meteorology stations of the Turkish State Meteorological Service, representing the Lower and Upper Gediz, Manisa and Akhisar plains, respectively. Long-term climatic variations and trends over the Manisa and Akhisar districts were analyzed by using time-series of annual and seasonal normalized precipitation index (NPI) and annual aridity index (AI). Nature and magnitude (statistical significance) of the observed long-term trends in the NPI and AI time-series were investigated with the non parametric Mann- Kendal rank correlation coefficient (τ) and the parametric least-squares linear regression methods. Trend tests applied to the NPI and AI time-series indicate that the Akhisar and Manisa districts have faced an apparent drying trend, and this trend has become stronger since the 1980s along with the severe drought events during the period of 2007 to 2008.