Before the implementation of any small scale hydropower scheme, it is essential to determine the availability of sufficient and reliable amount of water to make the scheme economically viable. The sites for small hydels are generally located in the inaccessible tracts of hilly regions. This hinders the proper evaluation of the site. The investments in the small hydels are also comparatively very low as compared to a big hydel power plant; as such not much of fund can be allocated to the initial site suitability decisions. Once a best site in a stream having suitable head has been identified then proper and detailed survey of the site could be undertaken for the construction of the plant. The streams on which small hydel plants are planned are mostly ungauged, which again poses a problem in identifying the amount of flow at certain location. In this work an attempt has been made to create a model for identification of flow at any location of a watershed. The two components of flow that is the base flow and runoff has been taken into consideration for calculating the flow. The base flow has been identified by direct measurement and run off has been delineated using the distributed curve number method. Finally a regression has been done to come to a generalized equation for determination of total flow at any point of a watershed in the Kalimpong subdivision.