Flood risk is a function of three factors namely, flood hazard, exposed land uses, and their vulnerability that threatens various aspects of life is flood. Such factors and their role have been examined in Kand watershed, 14 km northeastern Tehran in Iran. This study aims at preparing flood zoning maps in different return periods using HEC-RAS (Hydrologic Engineering Center -River Analysis System) and GIS (geographic information system); determining the vulnerability of buildings; providing the flood risk map regards to controlling land functions in the area of Kand Watershed. The land use map demonstrates that the distance separating the Kand River and buildings is negligible. HEC-RAS software is used to calculate surface water profiles for 100-year return period. Flood discharges are calculated with the values of 451.86 m3/s. The mean depth of water is 1.4m. The vulnerability analysis of buildings shows that if the flood with the depth of less than 70 cm occurs, most equipment of the buildings will be damaged. As a result, the flood risk is high in the areas that have less distance with river. Therefore, flood risks maps are useful in making more precise decisions and actions relative to risk reduction management and mitigation.