Abstract
ABSTRACT Generally, the base for any flood mapping is the topography information whose resolution determines the map accuracy. Furthermore, river bathymetry in detail and the type of used model are also relevant. Therefore, the objective of the present study was to evaluate the influence of different sources of topographic data on the flood mapping by using the CAESAR-Lisflood model and three Digital Elevation Model (DEM) configurations, among which two were freely available, and the other was generated with field survey (topography and bathymetry). First, the resolution and precision of each DEM were evaluated, from the comparison of different cross-sections, besides the variation of the wetted area and absolute value of the relative error in mean velocity as a function of depth. Subsequently, after elaborating flood maps with each DEM, the results were compared in terms of flood area, mean flood width and flow depth. It is observed that the more accurate resolution, the smaller the flood area becomes. The flood map elaborated with the DEM through field survey had the best fit to the observed area. However the relation between the topographic resolutions and flow-depths was not clear in obtained results.
Highlights
Hydrological disasters related to floods have been increasing considerably and causing serious socioeconomic and environmental damages including human losses in the world
After the transformation of the daily rainfall into an hourly one and the calibration of the hydrological model inserted in the CAESAR-Lisflood, it was determined the hyetograph for the 1982 event modifying the peak to 75% of the total duration
The computational mapping of areas susceptible to floods is an important tool in the flood disaster management
Summary
Hydrological disasters related to floods have been increasing considerably and causing serious socioeconomic and environmental damages including human losses in the world. In Brazil, the type of disaster that causes the largest number of deaths is flash flood with 58.2%, followed by mass movements. In terms of flash floods, the southern region of Brazil represents the largest records, with 39% (Universidade Federal de Santa Catarina, 2013). Based on the guidelines of the Brazilian National Policy on Protection and Civil Defense (PNPDEC) under Federal law 12.608/2012, and with the initiative of the Brazilian Geological Survey (CPRM), areas susceptible to flood were preliminarily elaborated for 881 municipalities that the National Plan for Risk Management and Natural Disasters Responses (PNGRRDN) considered very critical
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