Delimitation of flood areas based on a calibrated a DEM and geoprocessing: case study on the Uruguay River, Itaqui, southern Brazil

Abstract

Abstract. Flooding is a natural disaster which affects thousands of riverside, coastal, and urban communities causing severe damage. River flood mapping is the process of determining inundation extents and depth by comparing historical river water levels with ground surface elevation references. This paper aims to map flood hazard areas under the influence of the Uruguay River, Itaqui (southern Brazil), using a calibration digital elevation model (DEM), historic river level data and geoprocessing techniques. The temporal series of maximum annual level records of the Uruguay River, for the years 1942 to 2017, were linked to the Brazilian Geodetic System using geometric leveling and submitted for descriptive statistical analysis and probability. The DEM was calibrated with ground control points (GCPs) of high vertical accuracy based on post-processed high-precision Global Navigation Satellite System surveys. Using the temporal series statistical analysis results, the spatialization of flood hazard classes on the calibrated DEM was assessed and validated. Finally, the modeling of the simulated flood level was visually compared against the flood area on the satellite image, which were both registered on the same date. The free DEM calibration model indicated high correspondence with GCPs (R2=0.81; p<0.001). The calibrated DEM showed a 68.15 % improvement in vertical accuracy (RMSE = 1.00 m). Five classes of flood hazards were determined: extremely high flood hazard, high flood hazard, moderate flood hazard, low flood hazard, and non-floodable. The flood episodes, with a return time of 100 years, were modeled with a 57.24 m altimetric level. Altimetric levels above 51.66 m have a high potential of causing damage, mainly affecting properties and public facilities in the city's northern and western peripheries. Assessment of the areas that can potentially be flooded can help to reduce the negative impact of flood events by supporting the process of land use planning in areas exposed to flood hazard.

Tidal flood area mapping fronts the climate change scenarios: case study in a tropical estuary of Brazilian semiarid

“…Among its advantages, it does not require normal distribution of data and is only slightly influenced by abrupt changes or nonhomogenous series (Zhang et al, 2009). In recent years, with growing concerns over environmental degradation and about the implications of greenhouse gases on the environment, researchers and practitioners have frequently applied the non-parametric Mann-Kendall test to detect trends in recorded hydrologic time series such as water quality, streamflow, and precipitation time series (Yue and Wang, 2004;Araújo et al, 2019). Although it has no influence on the tidal flood risk mapping, the Mann-Kendall test was applied to investigate if the elevation of tides is showing any upward or downward trend.…”

Flood Mapping Uncertainty from a Restoration Perspective: A Practical Case Study

“…In this context, many multi-purpose restoration plans are triggered by flooding and related natural disasters that have a significant impact on socio-economic activities of populations in developed and developing countries around the world [4,5]. Thus, the process of determining inundation extents by the development of flood hazard maps, including the frequency of floods, and how they affect infrastructure and social activities in flood-prone areas is part of any restoration plan.…”

Modelling flood hazard in dry climates of southern Africa: a case of Beitbridge, Limpopo Basin, Zimbabwe

“…A summary of the environmental variables used in this study Areas of low elevation are prone to flooding compared to areas of high elevation(Araújo et al, 2019;Samela et al, 2016).Distance from water bodies Euclidean distance from a riverAreas close to rivers are more likely to be flooded than those further away(Budiyono et al, 2016;Death et al, 2015). A river map is needed to calculate the distances from rivers.…”