Increase in demand of water with passage of time for irrigation and hydropower lead Pakistan to conserve its all water resources. Unfortunately the absence of long term runoff record makes it difficult to estimate the availability of water. Therefore for estimation of runoff certain other techniques are in use but the most common method in practice is SCS-CN method. SCS-CN technique shows the catchment response of precipitation in the form of runoff. Mishira and Singh modified its equation by introducing two more parameter and redefining one term and finally recommended modified model of the existing SCS-CN method. The modified form of SCS Methods were used on different sized catchments i.e. Soan River, Ling River and Darmalak Dam to compared results with existing SCS-CN method for runoff estimation, as presented in this technical book. The author appreciate the efforts of Barthlemy Chaton and his team in providing guidance for book finalization and highly acknowledge publishing of it by VDM Publishing House Ltd. for scientific knowledge sharing globally, that certainly would be valued in near future.