Abstract

Flood plains and the area near to the rivers channels, because of their special circumstances such as fertility and water resources are appropriate situations for the social and agricultural activities, but due to morphological characteristics usually, these area are affected by different flood hazards. However, in these areas, determination of flood zone and its height and also detecting properties of floods in different return periods is most significant. So flood zonation is essential for a proper development and most important parameter for investigate of ecological and environmental consequence. Interaction between some river hydrologic models and geographical information systems (GIS) cause some gains and methods, which are reasonable to the planners. This study was carried out with the purpose of using hydraulic model of HEC-RAS with Arc View software to estimate the flood zone of 5 km distance on Neka River in Northern part of Iran, where during the last decade we had different flood events with a high magnitude damages. Topography maps at 1:1000 scale were used for the flood zonation for different periods of 2, 5, 10, 25, 50, 100 and 200 years. The results obtained attest to the fact that the combination of GIS and HEC-RAS model used in this study is useful and efficient in delineating the flood zonation. Finally the flood zone of 25 years is predicted to be more hazardous than the other periods for the selected areas.

Key words: Neka River, flood zonation, HEC-RAS, geographical information systems.