Abstarct: Increasing demands for water, necessitate management of surface water resources. Duo to the high variabilites in rainfall, and population growth and the need for new water resources, transfer of water from the high altitude basins have been considered, recently. The study area is located at north of Bastam plain. Rainfall at northern flanks of the Alborz mountain is considerably more than the south. There is no shortage of water at the northern regions of Alborz mountains and part of the surface water are being drained into the sea, annually. Groundwater levels at Bastam plain in south of Alborz are being decreased sharply, with an annul average rate of about 80 cm. Field Studies and satellite images indicate that, there are 15 basins on the northern flanks of the Alborz mountain in which their surface waters can be transferred to south regions using a 2 Km long tunnel. Volume of runoff in each basins was estimated by (SCS) and rational techniques. For more accurate estimation of curve number (CN) in the SCS method and runoff coefficient in rational technique, a new quantitative method baxsed on calculation runoff index was applied. To determine the runoff index, lithology, vegetation cover and slope of the study area were considered. These parameters according to their influence on runoff index were classified with a score from two to ten, for each class. The laxyers were weighted averaged using Arc GIS 9.3 and runoff index was calculated. This value was converted to CN and runoff coefficient considering hydrological conditions. Finally, volume of runoff was estimated by SCS and rational methods. Calculated volume of runoff were about 5 and 4.7 MCM per year, by SCS and rational methods, respectively, for different basins.