Gharib - Azad University of savadkooh
Mosaedi - Dep. of Water Eng. Gorgan University of Agricultural Science and Natural Resources
Najafinejad - Dep. Of Range & Watershed Management, Gorgan University of Agricultural Science and Natural Resources

Recognition of river behavior and performing salubrious activities with nature has always been the titillation of engineers in this field. They always need an instrument for simulation of the related phenomenon in the river. Without this tool, the engineer’s grudges cause the related plans to be carried out with more conservatism that usually cost more and are often untechnical. In this study to determine the amount of the submergible areas at two conditions like resistance and demolition of the bridge, after some calculations about the level of water flooding area map was drown. Considering water level profile, flooding area for discharge for every return period was determined. After that period the flooding area for discharge for different return periods was drown and calculated by AUTOCAD software and the mensuration of each area was calculated by AUTOCAD software. After some surveying about the extent of flooding areas of any zones in two states of resistance and destruction of the bridge it was observed that by destroying the main bridge the extent of the flooding areas decreased considerably and the amount and extent of flooding area in return period in case of destruction of the bridge reaches only 10 percent of the resistance condition of the bridge in 100 years and mean while the number residential units which are under the influence of flood in the left bank decrease to one second.

water level-profile, AutoCAD Software, flooding area