Throughout human history, the river was the center of development and ancient civilizations formed in the margins of rivers like the Nile, Euphrates, Tigris, Indus, Danube, Volga and a Karoon and others. Deleterious effects of human occurred in the vicinity of river beds by several ways. The simulation of the hydraulic behavior of the river basin boundaries is important for river engineering projects, prediction of flood damages in different conditions and economic feasibility studies, flood control, and other social programs related to the system of the river. In order to determine the boundaries of the Zayandeh roud river bed from Zayandehroud regulated dam to Nekouabad diversion dam, different softwares used and combined including ArcGIS, HEC-RAS and HEC-GeoRAS. The results showed that in the downstream of the dam, the river paths mainly through narrow valleys and steep areas and the villages located along the rivers constructed the pumping stations to transfer water to the highlands and hills to irrigate gardens. So it is very clear the invasion to the river banks. A small part of riverside locates traditional canals and gardens and occupied the bank river. In downstream, specially around Baghbahadoran city, in addition to the old rural and urban centers, there are massive activities to construct villas in recent years. The results show in the upstream, 85% of standard river bank and obtained measures in this research have not been considered. In the middle part of stream, 70% of standards and 90% obtained measure in this research has not been considered due to over population. In the downstream there is a small band in river bank due to less length and low land gradient. In this part 50% of standard river bank and 70% of obtained band have not been considered. Key Word : River, Bed Privacy, Zayandehroud, Flood Zoning
