Climatology of South Marmara Division (North West Anatolia) and observed variations and trends

Abstract

The study area is located in the northwestern part of Anatolia, Southern Marmara. Stations in the study area are characterized mainly with the Marmara transition climate and the Mediterranean rainfall regime. The climate of the sub-section was explained by determining the general climatic characteristics of the stations. In addition, long-term changes and trends in the time series of precipitation and stream-flow stations were investigated in terms of climatic variability by using nonparametric time series analysis methods. The results obtained are summarized as follows:

i) According to the Thornthwaite climate classification system, Bayramiç, Biga, Çan  and Bandırma stations have a severe water deficit in summer. The climate of the study area is semi-humid (Bayramiç, Biga, Çan, Bandırma) and dry-semi-humid (Edremit and Bozcaada). ii) In the south of Marmara, the stations having the Mediterranean rainfall regime are dominated with decreasing trend in annual precipitation amounts.  Decreasing trends in precipitation totals over the study area started in the 1970s and gradually became evident during the 1990s. iii) Topographic features, characteristics of pressure systems and air circulation are the basic factors that determine the climate characteristics of temperature and rainfall distribution in space and time. iv) Series of stream-flows in south of the Marmara have a significant decreasing trend since the 1990s in winter. v) Increasing evapotranspiration in the spring, summer and autumn, high seasonality and year-to-year variability of precipitation totals, and significant increases in air temperatures are the biggest threats to the regional water resources. In addition, increased use of streams for irrigation purposes also caused significant decreasing trend in stream-flows.