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

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.

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Delimitation of Flood Areas Based on Calibrated DEM and Geoprocessing: Case Study on Uruguay River, Itaqui City, Southern Brazil

10.5194/nhess-2018-212 ◽

2018 ◽

Author(s):

Paulo Victor N. Araújo ◽

Venerando E. Amaro ◽

Robert M. Silva ◽

Alexandre B. Lopes

Keyword(s):

Statistical Analysis ◽

Flood Hazard ◽

Satellite Image ◽

Ground Surface ◽

Water Levels ◽

Calibration Model ◽

Southern Brazil ◽

Temporal Series ◽

Flood Level ◽

Uruguay River

Abstract. Flooding is a natural disaster which affects thousands of riversides, coastal and/or urban communities causing severe damages. River flood mapping is the process of determining inundation extents and depth by comparing historic river water levels with ground surface elevation referenced. This paper aims to map flood geohazard areas under the influence of the Uruguay River, Itaqui city (Southern Brazil), using calibration Digital Elevation Model (DEM), historic river level data and Geoprocessing techniques. The annual maximum for years of 1942 to 2017, of fluviometric temporal series records of Uruguay River were linked to Brazilian Geodetic System using geometric levelling and submitted the statistical analysis. The DEM was calibrated with Ground Control Points (GCP) of high vertical accuracy based on post-processed high-precision GNSS surveys. Using the temporal series statistical analysis results, was assessed the spatialisation of flood hazard classes on the calibrated DEM and validated. Finally, was visually compared the modelling of the simulated flood level versus flood area on satellite image, which both were registered on the same date. The free DEM calibration model indicated high correspondence with GCPs (R2 = 0.81; p

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Panchromatic Satellite Image Classification for Flood Hazard Assessment

Journal of Applied Research and Technology ◽

10.22201/icat.16656423.2012.10.6.350 ◽

2012 ◽

Vol 10 (6) ◽

Cited By ~ 3

Author(s):

Ahmed Shaker ◽

Wai Yeung Yan ◽

Nagwa El-Ashmawy

Keyword(s):

Maximum Likelihood ◽

Hazard Assessment ◽

Flood Hazard ◽

Satellite Image ◽

Image Data ◽

Maximum Likelihood Classifier ◽

Flood Hazard Assessment ◽

Before And After ◽

High Flood ◽

Occurrence Matrix

The study aims to investigate the use of panchromatic (PAN) satellite image data for flood hazard assessment with anaid of various digital image processing techniques. Two SPOT PAN satellite images covering part of the Nile River inEgypt were used to delineate the flood extent during the years 1997 and 1998 (before and after a high flood). Threeclassification techniques, including the contextual classifier, maximum likelihood classifier and minimum distanceclassifier, were applied to the following: 1) the original PAN image data, 2) the original PAN image data and grey-levelco-occurrence matrix texture created from the PAN data, and 3) the enhanced PAN image data using an edgesharpeningfilter. The classification results were assessed with reference to the results derived from manualdigitization and random checkpoints. Generally, the results showed improvement of the calculation of flood area whenan edge-sharpening filter was used. In addition, the maximum likelihood classifier yielded the best classificationaccuracy (up to 97%) compared to the other two classifiers. The research demonstrates the benefits of using PANsatellite imagery as a potential data source for flood hazard assessment.

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Validating the vertical quality of SRTM digital elevation model of the Mirim Lagoon hydrographic basin

Abstracts of the ICA ◽

10.5194/ica-abs-1-136-2019 ◽

2019 ◽

Vol 1 ◽

pp. 1-2

Author(s):

Andrea Lopes Iescheck ◽

Patricia Andréia Paiola Scalco

Keyword(s):

Statistical Analysis ◽

Digital Elevation Model ◽

Precise Point Positioning ◽

Post Processing ◽

Srtm Dem ◽

Hydrographic Basin ◽

Digital Elevation ◽

Vertical Accuracy ◽

Elevation Model ◽

Srtm Data

Abstract. This work is part of a research project that aims at the automatic determination of knickpoints and the assessment of morphometric and hypsometric parameters of Mirim Lagoon Hydrographic Basin, using Shuttle Radar Topography Mission digital elevation model (SRTM-DEM) and spatial analyses.The analysis of geomorphologic systems is done using computational treatment of data obtained by remote sensing, especially those obtained by SRTM. These data permit the elaboration of a topographic model for the Earth surface and provide a base for studies in several units of geomorphologic analyses (geomorphologic systems), such as hydrographic basins.The most usual technique for derivation of relief morphologic attributes is based on digital elevation models (DEMs) and digital hydrographic nets. Computational routines are applied on those data for acquisition of the hydrography and drainage anomalies. The DEMs and the hydrographic nets must have either morphologic or hydrologic consistency to validate the results obtained in the morphometric analyses.More specifically, this study aims at describing the method and related results regarding the validation of the vertical accuracy of SRTM-DEM through a kinematic positioning based on the Global Navigation Satellite System (GNSS), in the Mirim Lagoon Hydrographic Basin region. Mirim Lagoon Hydrographic Basin is as cross-border basin located on the Atlantic coast of South America, and covers an area of 58,407.78&thinsp;km2, where 47% of this area is in Brazil and 53% in Uruguay.Several studies deal with the validation of Digital Elevation Models (DEMs) and SRTM data using different GNSS surveying methods and receivers. The innovation of this work is the methodology developed to achieve the suitable accuracy for the control points coordinates to validate the SRTM-DEM of Mirim Lagoon Hydrographic Basin. The study used the kinematic relative positioning method with a recording rate of 1 second and without reference stations for post-processing with the precise point positioning (PPP) method. This methodology allowed covering a large area with reference stations being very far from the surveyed region and with different geodetic reference systems (two countries).The methodology entails the GNSS data acquisition and post-processing, the transformation from geometric heights into orthometric heights, the SRTM-DEM mosaic, the extraction of homologous points in the SRTM-DEM and the statistical analyses for validating the model.The study used a GNSS receiver of dual-frequency with recording rate of 1 second to collect a total of 275,916 points with 3D coordinates. Those points were post-processed using the PPP method with the Canadian Spatial Reference System &ndash; Precise Point Positioning (CSRS-PPP), and the ellipsoidal height was converted into orthometric height through the software INTPT geoid. During this work, we used the geopotential model (EGM96) to transform height differences between two countries, Brazil and Uruguay.In order to obtain the SRTM-DEM we used 15 SRTM images, version 3, band C, with a spatial resolution of 1 arcsecond (approximately 30&thinsp;m). These images were individually processed to obtain the Digital Elevation Model Hydrologically Consistent (DEMHC) and to treat the inconsistencies. Afterwards, we created a mosaic with the 15 images.In the statistical analysis we examined the magnitude of absolute errors in the SRTM data. These errors were named discrepancies between the SRTM heights and the heights of GNSS survey points. After the post-processing and the heights conversion, the GNSS survey points were considered accurate and used as a reference for SRTM-DEM validation. The goal of the statistical analysis was to verify if the absolute vertical precision of the DEM data exceeds 16&thinsp;m, according to the precision specifications of the DEM SRTM.Results showed that the vertical mean absolute error of the SRTM-DEM vary from 0.07&thinsp;m to &plusmn;&thinsp;9.9&thinsp;m with average of &minus;0.28&thinsp;m. This vertical accuracy is better than the absolute vertical accuracy value of &plusmn;&thinsp;16&thinsp;m published in the SRTM data specification and validates the SRTM-DEM. Besides that, even considering different slopes and different heights the statistics showed that SRTM-DEM could be validated, in spite of the results for lower and flat area were more accurate than the ones for a higher area with high slope.

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Analysis of Flood Vulnerability as a Support to Water Sensitive Urban Design Planning in Klaten Regency

MEDIA KOMUNIKASI TEKNIK SIPIL ◽

10.14710/mkts.v26i2.31929 ◽

2021 ◽

Vol 26 (2) ◽

pp. 183-193

Author(s):

Desyta Ulfiana ◽

Yudi Eko Windarto ◽

Nurhadi Bashit ◽

Novia Sari Ristianti

Keyword(s):

Land Use ◽

Urban Design ◽

Flood Hazard ◽

Flood Management ◽

Flood Vulnerability ◽

Geological Conditions ◽

Order Preference ◽

Water Sensitive Urban Design ◽

High Flood ◽

High Level

Klaten Regency is one of the regions that has a high level of flood vulnerability. The area of Klaten Regency which is huge and has diverse characteristics makes it difficult to determine an appropriate flood management model. Water Sensitive Urban Design (WSUD) is a model that focuses on handling water management problems with environmentally friendly infrastructure. Therefore, an analysis is carried out to determine the level of flood vulnerability and factors causing flooding to plan a WSUD design that is suitable for each sub-districts of Klaten Regency. The Analytical Hierarchy Process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) methods are used to help the analysis. Aspects used as criteria are rainfall, slope, soil type, geological conditions, and land use. Based on the analysis, it could be concluded that Klaten Regency has two sub-districts with high flood hazard category, 21 sub-districts with medium category, and three sub-districts with low category. Bayat and Cawas are sub-districts that have a high level of flood vulnerability category. Meanwhile, Kemalang, Karangnongko and Polanharjo are districts with a low level of flood vulnerability category. The main factors causing flooding in Klaten Regency are slope and land use.

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Assessing the susceptibility of schools to flood events in Iran

Scientific Reports ◽

10.1038/s41598-020-75291-3 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Saleh Yousefi ◽

Hamid Reza Pourghasemi ◽

Sayed Naeim Emami ◽

Omid Rahmati ◽

Shahla Tavangar ◽

...

Keyword(s):

Flood Risk ◽

Flood Hazard ◽

Rural Students ◽

Flood Hazards ◽

Analytic Hierarchy ◽

Flood Susceptibility ◽

Susceptibility Maps ◽

High Flood ◽

Analytic Hierarchy Process Method ◽

Very High

Abstract Catastrophic floods cause deaths, injuries, and property damages in communities around the world. The losses can be worse among those who are more vulnerable to exposure and this can be enhanced by communities’ vulnerabilities. People in undeveloped and developing countries, like Iran, are more vulnerable and may be more exposed to flood hazards. In this study we investigate the vulnerabilities of 1622 schools to flood hazard in Chaharmahal and Bakhtiari Province, Iran. We used four machine learning models to produce flood susceptibility maps. The analytic hierarchy process method was enhanced with distance from schools to create a school-focused flood-risk map. The results indicate that 492 rural schools and 147 urban schools are in very high-risk locations. Furthermore, 54% of rural students and 8% of urban students study schools in locations of very high flood risk. The situation should be examined very closely and mitigating actions are urgently needed.

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Effect of Moisture and Incubation Time on Ochratoxin A Production by an Isolate of Aspergillus ochraceus

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/53.1.89 ◽

1970 ◽

Vol 53 (1) ◽

pp. 89-91

Author(s):

A F Schindler ◽

Stanley Nesheim

Keyword(s):

Statistical Analysis ◽

Moisture Content ◽

Ochratoxin A ◽

Incubation Time ◽

Maximum Yield ◽

Water Levels ◽

Aspergillus Ochraceus ◽

Ambient Temperatures ◽

Incubation Periods ◽

Transfer Needle

Abstract Experiments were conducted to determine the culture requirements that would insure a probability of high ochratoxin production with a given isolate. Experiments at ambient temperatures (72 ± 2°F) determined the levels of the two most readily controlled variables, time and moisture content, during the growth of a high toxin-producing isolate (M298) of Aspergillus ochraceus. Tests were conducted in 2.8 L - Fernbach flasks containing 100 g shredded wheat and inoculated with spores on a transfer needle. Amounts of ochratoxin A/flask were determined by comparison against standards on TLC after chloroform extraction. Statistical analysis showed a relation between ochratoxin yield, water levels, and incubation periods. A water level of 40–70 ml/flask with an incubation period of 19-21 days at ambient temperatures should give a near to maximum yield of ochratoxin A.

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Statistical Analysis of the Stability of Rock Slopes

Journal of Marine Science and Engineering ◽

10.3390/jmse7030060 ◽

2019 ◽

Vol 7 (3) ◽

pp. 60 ◽

Cited By ~ 5

Author(s):

Marcel van Gent ◽

Ermano de Almeida ◽

Bas Hofland

Keyword(s):

Statistical Analysis ◽

Physical Model ◽

Model Tests ◽

Water Levels ◽

Test Series ◽

Length Effect ◽

Wave Flume ◽

Physical Model Tests ◽

Erosion Area ◽

The Stability

Physical model tests were performed in a wave flume at Deltares with rock armoured slopes. A shallow foreshore was present. At deep water, the same wave conditions were used, but by applying different water levels, the wave loading on the rock armoured slopes increased considerably with increasing water levels. This allowed an assessment of the effects of sea level rise. Damage was measured by using digital stereo photography (DSP), which provides information on each individual stone that is displaced. Two test series were performed five times. This allowed for a statistical analysis of the damage to rock armoured slopes, which is uncommon due to the absence of statistical information based on a systematic repetition of test series. The statistical analysis demonstrates the need for taking the mean damage into account in the design of rock armoured slopes. This is important in addition to characterising the damage itself by erosion areas and erosion depths. The relation between damage parameters, such as the erosion area and erosion depth, was obtained from the tests. Besides tests with a straight slope, tests with a berm in the seaward slopes were also performed. A new method to take the so-called length effect into account is proposed to extrapolate results from physical model tests to real structures. This length effect is important, but is normally overlooked in the design of rubble mound structures. Standard deviations based on the presented model tests were used.

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Risk-Based Early Warning System for Pluvial Flash Floods: Approaches and Foundations

Geosciences ◽

10.3390/geosciences9030127 ◽

2019 ◽

Vol 9 (3) ◽

pp. 127 ◽

Cited By ~ 6

Author(s):

Julian Hofmann ◽

Holger Schüttrumpf

Keyword(s):

Information System ◽

Early Warning ◽

Urban Areas ◽

Heavy Rainfall ◽

Flood Hazard ◽

Significant Risk ◽

Early Warning Systems ◽

Flash Floods ◽

Water Levels ◽

Heavy Rainfall Event

In times of increasing weather extremes and expanding vulnerable cities, a significant risk to civilian security is posed by heavy rainfall induced flash floods. In contrast to river floods, pluvial flash floods can occur anytime, anywhere and vary enormously due to both terrain and climate factors. Current early warning systems (EWS) are based largely on measuring rainfall intensity or monitoring water levels, whereby the real danger due to urban torrential floods is just as insufficiently considered as the vulnerability of the physical infrastructure. For this reason, this article presents a concept for a risk-based EWS as one integral component of a multi-functional pluvial flood information system (MPFIS). Taking both the pluvial flood hazard as well as the damage potential into account, the EWS identifies the urban areas particularly affected by a forecasted heavy rainfall event and issues object-precise warnings in real-time. Further, the MPFIS performs a georeferenced documentation of occurred events as well as a systematic risk analysis, which at the same time forms the foundation of the proposed EWS. Based on a case study in the German city of Aachen and the event of 29 May 2018, the operation principle of the integrated information system is illustrated.

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Development of high-resolution multi-scale modelling system for simulation of coastal-fluvial urban flooding

Natural Hazards and Earth System Science ◽

10.5194/nhess-17-205-2017 ◽

2017 ◽

Vol 17 (2) ◽

pp. 205-224 ◽

Cited By ~ 4

Author(s):

Joanne Comer ◽

Agnieszka Indiana Olbert ◽

Stephen Nash ◽

Michael Hartnett

Keyword(s):

Moving Boundary ◽

Flood Hazard ◽

Hazard Identification ◽

Water Levels ◽

Urban Flooding ◽

Coastal Zones ◽

Urban Flood ◽

Multi Scale ◽

Scale Modelling ◽

Modelling System

Abstract. Urban developments in coastal zones are often exposed to natural hazards such as flooding. In this research, a state-of-the-art, multi-scale nested flood (MSN_Flood) model is applied to simulate complex coastal-fluvial urban flooding due to combined effects of tides, surges and river discharges. Cork city on Ireland's southwest coast is a study case. The flood modelling system comprises a cascade of four dynamically linked models that resolve the hydrodynamics of Cork Harbour and/or its sub-region at four scales: 90, 30, 6 and 2 m. Results demonstrate that the internalization of the nested boundary through the use of ghost cells combined with a tailored adaptive interpolation technique creates a highly dynamic moving boundary that permits flooding and drying of the nested boundary. This novel feature of MSN_Flood provides a high degree of choice regarding the location of the boundaries to the nested domain and therefore flexibility in model application. The nested MSN_Flood model through dynamic downscaling facilitates significant improvements in accuracy of model output without incurring the computational expense of high spatial resolution over the entire model domain. The urban flood model provides full characteristics of water levels and flow regimes necessary for flood hazard identification and flood risk assessment.

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Spatial Patterns and Characteristics of Flood Seasonality in Europe

10.5194/hess-2017-649 ◽

2017 ◽

Cited By ~ 1

Author(s):

Julia Hall ◽

Günter Blöschl

Keyword(s):

Cluster Analysis ◽

Geographical Location ◽

Bimodal Distribution ◽

Water Levels ◽

Mountainous Areas ◽

Continental Scale ◽

High Flood ◽

National Boundaries ◽

Autumn And Winter ◽

Flood Characteristics

Abstract. In Europe, floods are typically analysed within national boundaries and it is not well understood how the characteristics of local floods fit into a continental perspective. To gain a better understanding at the continental-scale, this study analyses seasonal flood characteristics across Europe for the period of 1960–2010. The timing within the year of annual maximum discharges or water levels of 4105 stations from a European flood database is analysed. A cluster analysis is performed to identify regions with different flood seasons. The clusters are determined using the monthly relative frequencies of the annual maxima, and are further analysed to determine the temporal flood characteristics of each region and the European-wide patterns of bimodal and unimodal flood seasonality distributions. Below 60° latitude, the mean timing of floods of individual stations transitions from winter floods in the West to spring floods in the East. Summer floods occurring in mountainous areas interrupt this West to East transition. Above 60° latitude, spring floods are dominant, except for coastal areas in which autumn and winter floods are observed. The temporal concentration of flood occurrences around a specific time of the year is highest in North-Eastern Europe, with most of the floods being concentrated within 1–2 months. The cluster analysis suggests that six regions with geographically distinct flood seasonality distributions exist. Most of the stations (~ 73 %) with more than 30 years of data exhibit a unimodal flood seasonality distribution (one or more consecutive months with high flood occurrence). Few stations (~ 3 %), mainly located on the foothills of mountainous areas, have a clear bimodal distribution. Overall, the geographical location of a station in Europe can give an indication of its flood characteristics throughout the year and is more relevant than catchment area and outlet elevation for the observed flood seasonality.

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