Application of Thornthwaite moisture index to some areas in Türkiye

The source of water, the basic need of all living things in nature, is rainfall. When the same amount of rainfall is insufficient or does not fall globally, some regions experience drought problems. In some areas, floods occur due to excessive rainfall. Apart from the normal process of drought and flood, human interventions such as global warming also play an active role in the occurrence of both natural disasters. In order to track drought, several moisture indices have been developed in the literature. Moisture conditions and the extent of a water deficit in a particular area are usually ascertained using moisture indices, characterizing the equilibrium between water inflows and outflows. In this study, Thornthwaite moisture index (TMI) was used to evaluate moisture deficit. The study was conducted in the provinces of Tokat, Kayseri, Ankara, Konya, Karaman, Afyon, Denizli and Burdur. The first effort for this purpose was made according to the Innovative Polygon Trend Analysis (IPTA) of seasonal variation of rainfall and potential evapotranspiration (PET) values. Regular polygons were not obtained at any station in both data sets. Although precipitation data showed a general decreasing trend in all stations during the summer months except June, PET values had the opposite pattern. The monthly TMI index for all stations showed that there was a moisture deficit from April (except for the Afyon station) to October. A striking finding in the annual TMI results was that negative values were detected at all stations. These findings will contribute to relevant decision makers in water-related planning and awareness studies.