Aim of the study:
The use of underground water for drinking water supply has increased over the recent years, due to intensive pollution of local and transboundary rivers in the Greater Caucasus region of Azerbaijan. In addition to relatively deep groundwaters, undergroundflow of rivers are also widely used for the purpose. The purpose of the present study is to analyze the condition of undergroundflow of rivers in the region and to determine its territorial distribution patterns.

Material and methods:
The possibilities of using the minimum monthly water discharge have been investigated to determine the annual rates of underground flow to rivers. The study was conducted in 4 options and in each option the values obtained based on the minimum monthly discharge of underground flow have been compared to values obtained based on hydrographs separation drawn up for typical years.

Results and conclusions:
The underground flow coefficient, which is a quantitative indication of feeding of groundwaters by infiltration in the Greater Caucasus region, is affected by the physical and geographical factors. As the average altitude increases, the underground flow coefficient also increases. Thus, the average altitude of catchment area is an integral indicator of the physical and geographical factors affecting the feeding of groundwaters by infiltration. The differences between the average multi-year values of the Greater Caucasus rivers baseflow coefficient and coefficient of feeding by groundwater is about 0.25. In study area, the coefficients of feeding by groundwater for the rivers is averagely 63.85% in dry water years, 55.2% in medium-water years and 59.5% in wet water years.