Research on methods for mapping suitable areas for flood spreading, using RS and GIS. Case study: West of Khorasan province.
2008
Dad Rasi Sabzevar, Abu Al-Qasem | Jalali, Nader | Gohari, Ebrahim | Farzaneh, Hossein
Flood Water and need for best operation of water in Iran, is very important. Mapping of suitable areas for flood spreading by traditional methods usually is very expensive and take up time. Using GIS and RS can reduce such costs. The study area is located in the great khorasan province ( Sabzevar, Esferayen, Kashmar, Bardeskan, Jagarm and Khalilabad). The main objective of present study is, research on methods for mapping suitable areas for flood spreading. In order to meet this general objective, seven maps were used. Quaternary deposits, land use, slope, infiltration rate, runoff, Storage coefficient and bed rock depth. Map of Quaternary deposits was prepared from geological map at scale of 1:250000 and controled by photo-interpretation. 43 sites were selected by field survey. The slope map was obtained by GIS. Landuse was prepared by visual interpretation, using R.G.B.742 of ETM+ images. Infiltration rate in each area was calculated by double ring test. Geoelectric study was used for bed rock depth estimation. Storage coefficient for each site was calculated by typical table related on soil texture, and finally volumes of overland flow were calculated for all sites. The above mentioned maps as the information layers in GIS and conceptual method were used. Booleain logic, index overlay and fuzzy logic were selected and tested in those areas. The result shows that the GIS and RS are suitable for this study. Also the Fuzzy Algebric sum is the best, but if the classes be reduced to 4, the Fuzzy Gamma 0.5 becomes more convenient than Fuzzy Gamma 0.8.
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