Surveying Spatial Effect of Influencing Areas on Peak flood Discharge to decreasing flood damages in Iran watersheds
2006
Roghani, Mohammad | Ghafori, Abdolmajid | Tabatabaei, Mahmoud reza | Ghyasi, Najafgholi
Due to particular geographic situation, Iran has arid and semi arid climate in most areas. Rainfall condition and distribution in these areas is influenced by the geographic characteristics which causes of seasonal floods. These floods imposes huge and irreparable damages. The aim of this research is decreasing of flood hazard. For this purpose by using time_area diagram, average slope, surface roughness coefficient, time of concentration, rain and runoff coefficient in a hydrologic model has calibrated and evaluated the behavior of watershed basin. Then isochron of basin was determined and spatial distribution condition of sub-basins has been surveyed. Since interaction between sub-basins spatial distribution and turtiality potential has an important role in arise of peak flood discharge in basin outlet. Therefore considering the implementation of flood control activities in the sub basins located in each isochron, their effect on peak flood hydrograph has been analyzed. The results of this research indicate that the number five isochron in Polmanjenig catchment with 64.6 kmcz area and number five isochron in Bagmalek catchment with 21.1 lmc2 area has had the most effect in peak flood discharge in the basin outlet. In the contrary, the sub-basin located in isochron near outlet have had less important role in peak flood discharge. ln general, from the outlet toward middle stream of basin along with increase in areas of isochron, the effects of sub-basins in peak flood discharge has showed an increasing. Thus concentrating on watershed management and flood control activities based on priorities and the areas identified achieving the research goals, will lead to considerable decrease in implementation expenses of the project
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