The study of flood flow hydraulic for determining flood bed and river influences points (Atrak River case study)

Measures should be taken to make better use of the rivers in the study, construction and exploitation optimized to contain, mitigate risks and minimize the negative consequences and the improvement of the situation in order to meet human needs and protect the environment there. Route investigated in Khorasan Razavi province and city and river Ghochan is Atrak. Physiographic parameters using digital layers carefully 25,000: 1 in ArcGIS and ArcView analysis and were estimated. To estimate the return periods of floods in the area of methods of analysis, reasoning, Deacon, Krieger and Fuller were used. By comparing the flood estimation by different methods, field visits in this area, soil, vegetation, slope, main channel length, physical parameters and geographical limits of the study, ultimately in the sub Atrak (A1 to A6) results of Deacon, Was considered. Different regimes in the river hydraulic model HEC-RAS has been simulated. The results of the flow regime was selected for the river. Then enter the results of the HEC-RAS model in GIS environment due to the topography of the river and the water surface profile.Results indicated that the average depth of the river terraces formed by the left and right on the beach between 5.2 m and the effects of erosion can be seen in more than 50% along the way. Intervals of high erosion potential (H4T4-H3T3-H3T4) more visibility in the population centers, which are thus the threat of riverbank protection programs during the route. With regard to the agricultural land and rivers in designing and building the necessary measures to be considered in this context. The results of the final balance of the river and move the threshold conditions at all levels stable river cross sections showed that 71 percent of the unstable situation in stable situation is the remaining 29%. Results of sensitivity analysis showed that the highest sensitivity to changes in the parameters of the roughness coefficient and flow area is the width of the upper level.