Journal of Applied Sciences1812-56541812-5662Asian Network for Scientific Information10.3923/jas.2009.3723.3730V.Gholami E.Jokar M.Azodi H.A.Zabardast BashirgonbadM. 122009920Destroy of forest lands and changing them into agricultural and range lands has been followed by the development of human societies and increase of mans activities in the Northern part of Iran. These land use changes and also the development of road network and residential areas have caused to increase runoff generation and flood hazard. We have observed the development of residential areas, road network and destroy of forest lands in Kasilian watershed in the recent several decades. Kasilian watershed is located in the Northern part of Iran. The objective of this study has been the quantitative investigation of the effects of mans activities on the destroy of forest lands, land use changes, impervious surface development and finally the influence of the set of these changes on runoff generation and flood hazard in Kasilian watershed. The study of land use changes and residential area development has been carried out by using aerial photos, topographic maps 1:25000, land use maps and satellite images. Also a runoff-rainfall model has been presented by using GIS (HEC-GeoHMS extension) and hydrologic model (HEC-HMS). We used the SCS method for presenting the hydrologic model. It is noted that the optimized model is evaluated by the other six events of flood. Then land use changes and also the development of the residential areas and roads have been included in the evaluated hydrologic model and their effects on intensifying runoff generation and flood hazard have been investigated quantitatively during the recent forty years.]]>Brilly, M., S. Rusjan and A.Vidmar,20063110891096Burns, D., T. Vitvarb, J. McDonnellc, J. Hassettb, J. Duncanb and C. Kendalld,2005311266281Camorani, G., A. Castellarin and A. Brath,20053561574Dunjo, G., G. Pardini and M. Gispert,200457239256Foster, I., A. Gurnell and B.Webb,1995pp: 473pp: 473Hirsch, R.M., J.F. Walker, J.C. Day and R. Kallio,19901329359Katrien, D., N. Jan, P. Jean, R. Dirk, H. Mitiku, M. Bart and D. Seppe,2006331219241McGee, T.,20012912Pappas, E.A., D.R. Smith, C. Huang, W.C. Shuster and J.V. Bonta,20071277Riley, A.L.,19981st Edn.,pp: 445-448pp: 445-448Wahl, N.A., B. Wollecke, O. Bens and R.F. Huttl,200530611621Zimmermann, B., H. Elsenbeer and J.M. De Moraes,20052222938