The intensification of drought and unsustainable management of water resources has caused increasing demand for water resources. Interbasin water transfer has been implemented as an alternative solution method to this demand in last decades. This study presented the statistical investigation regarding hydrological effects of interbasin water transfer for karst areas in southern part of Turkey. In order to maintain water level above the critical level at Beysehir Lake (BL), the largest fresh water resource of Turkey, the water of Gembos Closed Basin (GCB), located at the south of the BL, has been diverted to the BL via Gembos Diversion Canal (GDC) since 2008. The main reason for diverting water to the BL was to save water level influenced by severe fluctuations due to irrigation water transferring to the Konya Plain. It was supposed that the GCB was feeding the Manavgat River (MR) in the south by way to dolines that the transfer zone located at densely karst area. Statistical analysis applied to the hydrometeorological data of adjacent basins showed a significant relation between flow of the MR and adjacent basins. The cross-correlation functions between high correlation values of + 1 lag time indicates that precipitation occurring throughout the GCB affects the baseflow at the MR about a month later. The GDC caused 0.84 m increase in the level of the BL; however, it does not create a statistically significant change on the MR. The results also demonstrated that the GDC contributed positively to water level of the Lake despite irrigation water.