Effects of Threshold Drainage Area and Study Region Size on HAZUS Flood Analysis     

《制图学和地理信息科学》2013,40(2):93-104

This study investigates the trends and error bounds in HAZUS flood hazard modeling due to changes in two parameters: threshold drainage area and study region size. Using the city of Ozark, Missouri, U.S.A., as a case study area, we compared modeled floodplains, flood debris, and economic loss in 24 threshold drainage areas and 20 study region sizes. The results show that the total floodplain area and total economic loss decrease with increasing threshold drainage area while the total amount of flood debris has an increasing trend. A threshold drainage area of 2.00 square miles is regarded as the optimal parameter for future HAZUS flood modeling for Ozark, based on the comparison of modeled floodplains with the FEMA Q3 floodplains. The total floodplain area and total economic loss tend to be larger at a larger study region, while no clear trend has been observed in the amount of flood debris. A study region of one county is suggested for future flood modeling because this size produces stable flood estimates and is also a convenient choice.  相似文献   

Drainage Typification Based on Dendritic Decomposition     

《The Cartographic journal》2013,50(4):321-328

Abstract

Map generalisation is an abstraction process that seeks to transform the representation of cartographic objects from the original version into a coarser one. The characteristics of cartographic objects and the arrangement of map features have to be observed and preserved in a generalisation process. A method is developed for typifying drainages while preserving their structural characteristics, i.e.presenting the drainages with reduced number of rivers under the constraint of preserving the original structure in terms of the type and distribution of the rivers. We apply Töpfer's radical law to calculate the amount of the rivers to be retained on the generalised map. The drainages share the amount of retained rivers in proportion to the number of their tributaries. In each of the drainages, the shared amount is divided among the rivers based on the dendritic decomposition of the drainage. We implement and test the method in Java Environment. Results from case studies show that the method effectively preserves the original structures of the drainages on the generalised maps.  相似文献