Trends of monthly and annual water deficit and surplus in Turkey

Climate change affects many sectors directly or indirectly. Agriculture and agriculture-related sectors are the leading sectors effected from climatic change. The increase of temperatures or variation amount of rainfall will affect the agricultural activities in a field and new plan have to be done for these areas to eliminate the negative effects. There have been many studies on temperature and rainfall trends in Turkey, but the tendencies in the water deficit and surplus which are a function of both, have not been analyzed yet. The investigation of these tendencies is especially important for agricultural planning. This study was prepared to address this deficiency in the literature. For this purpose, the monthly average temperature and monthly rainfall data of 183 meteorological station covering the period between 1971-2010 years has been obtained and water budget for each year have been prepared for all stations. Water budget elements were analyzed with linear regression and Mann-Kendall (MK) test to define the tendencies. According to the results, the water surplus has decreasing in south and increase in north while the water deficits especially calculated in warm periods have decreasing trends whole of Turkey. Using the total annual water deficit and the water surplus has showed that Turkey separated four different regions according to these elements’ trends. These regions are; a) decreasing water deficit-increasing water surplus region b) decreasing water deficit- decreasing water surplus region c) increasing water deficit-increasing water surplus region d) increasing water deficit-decreasing water surplus region. In terms of agriculture, it is understood that the most negative effects in the context of climate change will be occur in increasing water deficit-decreasing water surplus region and these regions should be planned as a priority