Application of entropy weighting method for urban flood hazard mapping

Flooding is one of the most frequently occurring natural hazards worldwide. Mapping and assessment of possible flood hazards are critical components of the evaluation and mitigation of flood risk. In this study, six flood-related indices, i.e., slope, elevation, distance to discharge channel, runoff volume, street-drainage network intersection, index of the development and persistence of the drainage network (IDPR), were used to assess the flood hazard. The entropy weighting method was used for assigning the weights to flood-related indices and combining them to prepare urban flood hazard mapping in Hamadan city. The produced map showed that nearly 20% of the study area (14.7 km(2)) corresponded to very high susceptibility to flooding, 19.4% (143 km(2)) to high susceptibility and 20.3%, 20.7% and 19.6% regard the moderate, low and very low susceptibility to flooding, respectively. Finally, two methods were used to evaluate the accuracy of the produced flood susceptibility map. The first method is related to assessing the behavior of the map by making and propagating error in flood-related indices and used model (entropy weighting method), and the second method is superimposing method. The results showed that by making and propagation of error, the behavior of producing flood susceptibility mapping, the produced map has a robust behavior either in ranking importance of flood-related indices and percentage of flood susceptibility areas. On the other hand, regarding the result of the superimposing method, the accuracy of the flood susceptibility map was 72%, which also suggests an acceptable result.

Automated summary

Flooding is a common natural hazard globally, and assessing flood hazard through various indices is essential. In this study, six flood-related indices were used to produce an urban flood hazard map in Hamadan city, showing different susceptibility levels. The accuracy evaluation of the map using two methods demonstrated consistent results, with a 72% accuracy rate suggesting acceptability.