APPLICATION OF RS and GIS TO DETERMINE FLOOD ZONE MAPPING IN DAMAVAND RIVER, IRAN

Determination of flood zone mapping by using RS and GIS is the subject of research carried out in a reach of Damavand River. The objectives of this is to generate a digital elevation model and the method by which flood water propagation to be evaluated, then GIS techniques were applied to determine flood zone mapping for a specific reach of the river. It is impossible to determine the river flood zone mapping without its magnitude and behaviour in floodplain. However, in this research, HEC-HMS (1998) was applied to estimate flood hydrographs in eight sub-catchments of the river. In order to run HEC-HMS (1998), two sets of data were required. 1- Available data which contain rainfall, flood and soil type records. 2- Field work was also carried out to obtain longitudinal survey profile at 1:2000 scale as well as soil infiltration measurement using an infiltrometer and also Manning's roughness coefficient was estimated. Maps of land use, land cover and vegetation density were also provided by using RS, then digital elevation model (DEM) as well as slope maps for sub-catchments were generated in GIS, As a result, a map of SCS (1972) curve number (CN) was obtained. HEC-HMS (1998) was applied to estimate flood hydrographs at the outfall of the catchment. The outputs from HEC-HMS (1998) were used to estimate water surface elevation in MIKE 11 (1999). In the end, generated DEM as well as maximum water surface elevation along the river profile were applied for different flood return periods to determine flood zone mapping.