Rainfall-runoff relations in Marmara sea drainage basin

In Marmara Sea basin, it is detected that there is an increase trend in values of rainfall and runoff between 1985-2015 by using Mann-Kendall, Spearman's Rho, EKKDR and Kruskal Wallis test and this increase was seen in stations that have statistically significant changes as well. It also seen that the stations which are statistically change are inhomogeneous. The relation between PCA components of rainfall and runoff, which PCA analysis was applied on rainfall and runoff, and 500 hPa geopotential height, NAO, AO, SOI investigated via Pearson correlation coefficient. The results of correlation coefficient between PCA components of rainfall and runoff, and 500 hPa geopotential height and teleconnections show that basin is affected by northern air mass during wet period. Evaporation is the principal process in water balance of basin due to Mediterranean climate and evaporation also is affected by topography in which low areas have highest values of evaporation. The runoff coefficient is 0.42 in Marmara Sea basin. That circumstance demonstrate that even there is strong relation between rainfall and runoff even if it differentiate locally. It is seen that there is a negative correlation between water balance and runoff coefficient in which areas with high runoff coefficients is the areas where water balance show less negative values. On the one hand, many parameters such as rainfall, runoff, surface runoff, lateral flow, groundwater, soil water, percolation, actual evapotranspiration except potential evapotranspiration and evaporation from runoff in Marmara Sea basin will decrease in future with respect to reference period and outlier of parameters of water balance will be expected as result of climate change. On the other hand, most affected areas will be Simav Çayı, Koçayı, Orhaneli Çayı, Emet Çayı and Nilüfer çayı, respectively.