Spatial pattern of the flood disaster risk in the protected zone of the lower Yellow River embankment

Flood disaster risk is analyzed by using hydraulics simulating method in the protected zone of the embankment along the Huayuankou-Lankao section of the lower Yellow River. According to the results of hydraulics simulation and spatially distributed conditions of social-economic property, the index system for identifying flood disaster risk is established. Flood disaster risk is identified, and spatial pattern of that is analyzed by means of map algebra functions of geographic information system (GIS) and synthetical cluster of fuzzy mathematics. The results show that the first grade flood disaster risk zone is mainly located in the northeast of the study area, with an average floodwater depth of 1.36 m, average flood velocity of 0.33 m/s, average GDP density of 4.35 million yuan/km(2), and average population density of 841.43 person/km(2); the second grade flood disaster risk zone is mainly distributed in the northwest of the study area; the third grade mainly in the southeast; the fourth grade mainly in the southwest; and it is relatively safe in the rest of the zones. This attempt on the methods and technique for identifying flood disaster risk can serve as a reference to the researches in other similar regions.