Flood Analysis Research Articles

Analysis of compound floods from storm surge and extreme precipitation in China

To enhance flood protection and risk reduction in China's coastal cities, it is crucial to comprehend the variability and underlying causes of compound floods along the coasts arising from storm surges and intense precipitation. The variability of compound floods from storm surge and extreme precipitation from 1958 to 2014 was analyzed using daily maximum sea level data and daily cumulative precipitation from 16 tide gauges along the coast of China. More than 70 % of the storm surges that caused damage from 1989 to 2014 at 14 out of 16 tide gauges were compound floods. We found a strong and seasonally varying dependence between storm surges and extreme precipitation along the coast of China. There were generally positive trends for the annual number of compound events at tide gauges south of 35°N. Compound flood variability was related to large-scale climate modes. The Arctic Oscillation in March was significantly negatively correlated with the compound events at tide gauges north of 35°N, while the opposite was true at tide gauges south of 35°N. The compound events were significantly correlated with the Pacific Decadal Oscillation (PDO) in June at 10 of the 16 tide gauges, and negatively correlated with the Niño1 + 2 index in February at 7 of the 16 tide gauges. Precipitation extremes determine the changes in the occurrence of compound floods, and by modifying the East Asian summer monsoon and typhoons, the large climate modes are supposed to impact the occurrence of compound floods. Our findings can enhance our understanding of compound floods and provide an important reference for flood risk management, particularly for low-lying coastal cities in China.

Analysis of flooding and nature-based solutions in the improvement of urban drainage system

This paper studies the drainage system performance of a conventional system with concrete channels and a retention pond. Also, the analysis of runoff reduction by implementing a nature-based solutions (NBSs) technique of rainwater harvesting and recharge well. The case study site is located in an industrial area in West Karawang City, West Java. The analysis was carried out by simulating the flood event using rainfall data from the site for a 10-year return period. The flood simulation was performed using the Storm Water Management Model (SWMM). The model consists of the analysis of flooding events in the drainage system and retention pond and the analysis of flooding prevention scenarios. The result reveals that the cause of the flooding is an extreme rainfall event which leads to the large accumulation of water at one junction point. Moreover, although the capacity of the retention pond is sufficient, the discharge rate is way larger than the infiltration rate, so the overflow occurred and resulted in flooding. The scenario of widening the drainage channel and installing a pump in the retention pond provides a good solution scenario to prevent flooding. The implementation of rainwater harvesting and recharge well could reduce the surface runoff volume of 21%. Further study should be conducted to analyze the combination of conventional and NBSs drainage system performance under the highest daily rainfall of the series.

The Spatial Planning in Purworejo Regency-based Flood Hazard using Sentinel-1A Imagery

Flood disasters in Indonesia increased by 23% over a period of 70 years. In Central Java Province, the incidence of floods has also experienced a significant increase, including flooding in Purworejo Regency. Floods in Purworejo Regency occur in almost every rainy season in the same location. In 2020 and 2021, floods hit the same 13 villages. The utilization of the Sentinel-1A Imagery technology can quickly and accurately visualize the distribution of locations where there are indications of flood inundation. This research aims to do rapid flood mapping for spatial planning. The method used in this research is the processing of Sentinel-1A imagery, flood mapping in Purworejo Regency, validation test of processed Saentinel-1A imagery, and flood analysis with the Purworejo Regency Spatial Planning. The Sentinel-1A data processing is in the form of a combination process between Composite RGB and the Change Detection and Thresholding (CDAT) method. Sentinel-1A imagery was taken at two different times, namely when there was a flood and when there was no flood. The Flood Map Processed by Saentinel-1A imagery will be verified and validated. The validity test results using the Kappa coefficient are 0.841, and the accuracy value is 94%. The Kappa coefficient value and accuracy show that the flooding results from the Saentinel-1A image processing are valid and accurate. The results of the analysis between spatial planning and flood inundation in Purworejo Regency are > 50% of the flooded areas in the form of paddy fields and plantations.

Analisis Spasial Kenaikan Tinggi Permukaan Air Batang Sumani Menggunakan Model Permukaan Digital

The occurrence of flooding in the Batang Sumani area of ​​Solok Regency is caused by several things, including the low slope of the river, the river cross-section which is not wide enough, the topography of the plains, heavy bends along the river and silting due to sedimentation and the vulnerability to flood hazards which is quite high in the watershed area. The influence of the topography of the plains causes inundation on land managed and used by the community. In accordance with technological developments in digital mapping of the earth's surface, the earth's surface can be presented in the form of a three-dimensional map called a Digital Elevation Model (DEM). This DEM is used as a model, analysis and representation of conditions related to the earth's surface. The use of DEM in the process of analyzing inundation caused by surface runoff will help in identifying the coverage of inundation areas and water catchment areas. By using the Simulate water level rise / flooding analysis from the Global Mapper application it is possible to simulate water level rise / flooding which makes it possible to simulate the coverage or spread of water/flooding by increasing the water level to a certain depth and spatial analysis using the Geographic Information System can see the influence of the inundation area on land use managed by the community around the inundation area. So that the location and coverage of the inundation on land use can be obtained. Most of the inundation areas are in garden areas at 37.56%, rice fields at 23.83%, fields at 24.03% and residential areas at 13.67%. There was a significant increase in the water level rise of 2 meters.

Sentinel-1-based analysis of the severe flood over Pakistan 2022

Abstract. In August and September 2022, Pakistan was hit by a severe flood, and millions of people were impacted. The Sentinel-1-based flood mapping algorithm developed by Technische Universität Wien (TU Wien) for the Copernicus Emergency Management Service (CEMS) global flood monitoring (GFM) component was used to document the propagation of the flood from 10 August to 23 September 2022. The results were evaluated using the flood maps from the CEMS rapid mapping component. Overall, the algorithm performs reasonably well with a critical success index of up to 80 %, while the detected differences can be primarily attributed to the time difference of the algorithm's results and the corresponding reference. Over the 6-week time span, an area of 30 492 km2 was observed to be flooded at least once, and the maximum extent was found to be present on 30 August. The study demonstrates the ability of the TU Wien flood mapping algorithm to fully automatically produce large-scale results and how key data of an event can be derived from these results.

Physical Model Tests of Concrete Buttress Dams with Failure Imposed by Hydrostatic Water Pressure

Although the failure of a concrete dam is a complex and highly dynamic process, the current safety assessments of concrete gravity and buttress dams rely on a simplified 2D stability analysis, which neglects the load redistribution due to 3D monolith interactions and the valley shape. In addition, the estimation of breach parameters in concrete dams is based on assumptions rather than analyses, and better prediction methods are needed. Model tests have been conducted to increase the understanding of the failure behavior of concrete dams. A scale model buttress dam, with a scale of 1:15, consisting of 5 monoliths that were 1.2 m in height and 4 m in width, was constructed and loaded to failure using water pressure. The model dam had detachable abutment supports and shear keys to permit variations in the 3D behavior. The results showed that the shear transfer was large between the monoliths and that the failure of a single dam monolith is unlikely. A greater lateral restraint gives not only a higher failure load but also a better indication of impending failure. These findings suggest that the entire dam, including its boundary conditions, should be considered during a stability assessment. The results also suggest that the common assumption in dam safety codes that a single monolith fails during flooding analysis is not conservative. The dataset obtained provides a foundation for the future development of dam-monitoring alarm limits and for predictive models of dam-breaching processes.

Flood frequency and flood forecasting analysis of Krishna basin Andhra Pradesh

Floods are occurrences of natural hazards, frequent during the year in many rivers across the globe. Every year, several rivers in India are vulnerable to flooding, causing loss of property and life. Krishna is one of the major rivers in India which is vulnerable to flooding in every monsoon. In this study, flood analysis was conducted for the year 2019. Rainfall data from AWS was used to estimate discharge levels in dams during the monsoon of 2019. It was observed that moderate rainfall occurred in the months of August and September, corresponding to low rainfall and that extreme flooding occurred in the same month. Compared to the flood inundation map of the satellite, it shows a close relationship with the flood map of 2019 and the affected area. The study shows that proper analysis of rainfall will be helpful in predicting downstream floods. To evaluate the flood control situation with appropriate data management in the Krishna basin, the usage of flood water is strong. Such types of studies would help to provide reliable and prompt flood forecasts and advance warning to redirect the main river flow to small canals, which will help to mitigate, excavate and remediate flooding in any area.

MITIGASI BANJIR BERDASARKAN HUJAN 3 HARIAN MAKSIMUM TAHUNAN DENGAN SIMULASI PEMASANGAN PARAPET DI KOTA SURAKARTA

<em>Surakarta City often floods when there is high rainfall, according to BNPB 2016 three consecutive days of rain can cause flood disasters. Hydrological analysis is needed to determine the flood discharge due to the maximum three-day rain. With the development of TRMM satellite rain data technology can be used in hydrological analysis to overcome the problem of limited data availability at rainfall gauges. The purpose of this research is to determine the value of discharge, inundation area caused by a maximum of three days of rain. In addition, this research also evaluates flood events and determines appropriate efforts in overcoming floodwater runoff by installing parapets. The use of HEC-RAS software in this research is for flood analysis and simulation of parapet installation in areas experiencing river water runoff. The calculated flood discharge is the annual flood discharge from 2000 - 2019. The method of calculating the discharge uses HSS Gama 1. Then flood tracing is carried out to determine the area of inundation that occurs. The process of mapping and determining the extent of flooding that occurred in each sub-district was carried out with the help of software GIS. The highest flood area due to river runoff occurs in Laweyan Subdistrict, which is 45,80 ha. From this location, a parapet installation simulation was carried out as one of the flood mitigation efforts. Simulation of parapet installation was carried out in Pajang Village and Laweyan Village, after simulating parapet installation, the flood area for Laweyan Subdistrict was 2,21 ha. </em>

Hydrometeorological-modeling-based analysis and risk assessment of a torrential rainfall flash flood in a data deficient area in Wenchuan County, Sichuan Province, China

Hydrometeorological-modeling-based analysis and risk assessment of a torrential rainfall flash flood in a data deficient area in Wenchuan County, Sichuan Province, China

Implementation of HydroBID Model with Satellite-Based Precipitation Products in Guadalquivir Basin, Bolivia

The use of distributed precipitation data in hydrological models is critically important to simulate processes at a micro-basin scale. However, aerial precipitation at a high resolution is required to run these models. This study aimed to set up the HydroBID tool in the Guadalquivir River basin using satellite-based precipitation products. The employed products included GSMaP gauge version 6, interpolated rain gauges using Kriging, the combined GS product for Bolivia, and the proposed combined product for the Guadalquivir basin. The GS Guadalquivir was generated by combining the satellite-based product GSMaP gauge version 6 with the local rain gauge network. The main difference with GS Bolivia is the improvement of the resolution from 5 km to 250 m. An iteration scheme using 230 micro-basins was employed, reaching a correlation of 0.98 compared to the control dataset. By using the hydrological model with the precipitation products, the daily river discharge was obtained, showing a high correlation of 0.99 and efficiency of 0.96 in relation to observed data between 2000 and 2016 at Obrajes station. Simulated flows with Kriging and GS Guadalquivir products presented similarly high correlations compared to the observed flows. In the case of GSMaP and GS Bolivia, these products showed general underestimations of the simulated flows, reaching correlations between 0.28 and 0.91, respectively. Moreover, annual volumes were analyzed, where the overestimation of GSMaP, Kriging, and GS Guadalquivir showed similar characteristics concerning the distribution of specific river discharges and volumes. Therefore, HydroBID appeared to be a feasible tool with enough adaptability to use distributed precipitation and simulate flows at a micro-basin scale. Therefore, we recommend applying this scheme to other basins to carry out analysis of events, water balance, and floods and similar studies.

Hazards of a flooding event in the city of Gdansk and possible forms of preventing the phenomenon – case study

ABSTRACT The main objective is to examine the urban flood hazard in the city of Gdansk and to determine the possibilities of preventing this phenomenon. Hydrological and hydraulic modeling was used for the case study analysis of urban flood in Strzyża basin, applying the HEC-HMS and HEC-RAS systems. The result of modeling with the assumption of torrential rainfall with a duration of t = 1 h (from 35 to 58 mm) is the probability of pluvial flood occurrence divided into low probability (p = 10%), high probability (p = 1%) and catastrophic probability (p = 0.2%). The normal flow of the Strzyża stream at the mouth is 0.175 m3·s−1, while the modeling results indicate an increase in the flow depending on the assumed flood flow probability from about 41.8 m3·s−1 to 54.7 m3·s−1. In addition, the article presents the basic elements of the policy of the city of Gdańsk in the field of reducing the hazards of urban flooding.

Selection and application of Copula functions with dependence on its tail right to the joint frequency analysis (Q, V) of annual floods

través del análisis de frecuencias bivariado del gasto máximo (Q) y el volumen escurrido (V) anuales de las crecientes registradas. Las funciones Cópula (FC) son modelos probabilísticos basados en la dependencia entre Q y V, que establecen fácilmente su distribución bivariada con base en las funciones marginales previamente adoptadas o distribuciones de cualquier tipo, iguales o diferentes. La aplicación de las FC en las estimaciones hidrológicas mostró que un aspecto decisivo en su selección idónea está relacionado con la dependencia en el extremo derecho de los datos ("λ" _U^CFG) y la que tienen ("λ" _U) ciertas FC. Por lo anterior, en este estudio se exponen las FC: t de Student, Gumbel-Hougaard, Clayton Asociada y Joe, que muestran valores de "λ" _U que van en aumento. Se contrastan los valores de "λ" _U contra los "λ" _U^CFG obtenidos en 16 registros reales aleatorios de Q y V, para establecer la aplicabilidad de cada FC citada. Además, se procesa como aplicación numérica el registro de 26 datos de Q y V anuales de las crecientes de entrada a la presa Adolfo López Mateos (Humaya) del estado de Sinaloa, México. Por último, se exponen las conclusiones, las cuales destacan las ventajas de las FC en los análisis de frecuencias bivariados de crecientes.

A comprehensive method to estimate flood levels of rivers subject to ice jams: A case study of the Chaudière River, Québec, Canada

Abstract The main difference between an open-water (regular) flood and an ice jam flood is that it is normally the whole river length that is overtopped whereas an ice jam flood is localized to where the jam is located. Comparatively, the regular flood analysis can use the value of the extreme discharge as the main input parameter for a long river section, an ice jam flood needs to account for the probability of jams of various lengths and intensities occurring at specific locations under significantly variable discharges while having several mechanical ice parameters to be considered. Through the case study of the Chaudière River, the methodology presented in this paper demonstrates how to statistically characterize four significant inputs (jam location, jam length, jam properties and river discharge during jam event) into the widely used numerical river water model (HEC-RAS) and how Monte–Carlo simulations are generated to estimate probable ice jam floods along a whole river reach. The purpose of this article is to propose a robust methodology through a case study and asses the sensitivity that historical and mechanical parameters have as to why specific locations along the reach have higher 1:100 AEP ice-induced water levels as to 1:100 AEP open-water levels.

Coupled sink and flow accumulation analyses with single flow direction and multiple flow direction algorithms

Abstract A static flood analysis (SFA) toolset is implemented with the purpose of performing simplified, event-based flood inundation modeling. The simulation process is divided into two steps: a topographic sink analysis of the terrain followed by flow accumulation (FA) of runoff volumes. Both procedures are coupled to account for sink storage effects. The sink analysis procedure determines the morphology of present sinks that are utilized during FA to calculate the sink storage by solving a mass balance, whereby inflows are captured in each sink according to their capacity and overflows are routed further downstream. Each sink is enriched with a set of hydrological attributes such as the total inflow, overflow, and flood depth. The flood depth is then utilized to determine the flood extent and flood depths of each sink. Two main options are made available for the FA procedure: either a single flow direction (SFD) or a novel formulation of the multiple flow direction (MFD) algorithm. Both methods were compared in terms of their accuracy with results from the TELEMAC-2D finite-volume solver for an urban inundation model. Both methods showed good agreement when compared with the validation results, with the MFD method performing marginally better than the SFD method.

Modifying 2D surface models in urban flood analysis

Hydraulic models in urban flood analysis play a decisive role, as they obtain information about flood extension, flow patterns on the surface and in the pipe network comes at cost of time consuming model set up and computing time. Dual drainage models do have the advantage of more accurate results as they consider bidirectional interaction between surface and sewers. This can be crucial as for certain rainfall events the sewer system can have a decisive impact. The aim of this paper is to modify 2D surface models and consider the performance of the sewers according to design standards for sewer systems, without the actual coupling process. Therefore a time varying approach, as inflow capacity into the sewers, was designed which reduces the rainfall depth before surface run off occurs. For a one-hour storm event, the novel approach indicates a higher performance (about 13 %) of the sewer system in the first half of the rainfall event compared to using a constant drainage removal rate. The presented approach in this paper will be tested in further research.

Parameter Optimization of Coupled 1D–2D Hydrodynamic Model for Urban Flood Inundation

In this study, the sensitivity of the parameters was analyzed using PEST (Parameter ESTimation) to improve the accuracy of the runoff and flooding analysis in urban areas. Using four parameters (watershed width, roughness coefficient of impervious and pervious areas, and Manning’s roughness coefficient for conduits) with high sensitivity, six scenarios were created according to the number of parameters considered, and a PEST-SWMM (Storm Water Management Model) combined simulation was performed. The scenarios were applied to the Seocho 3, 4, 5, Yeoksam, and Nonhyun drainage basins in which inundation damage occurred due to the heavy rain on 21 July 2013. The sensitivity of the four parameters was in the order of Manning’s roughness coefficient for conduits, the roughness coefficient of the impervious area, the watershed width, and the roughness coefficient of the pervious area. When the PEST–SWMM coupled analysis for each scenario was performed using the analyzed sensitivity results, the RMSE (Root Mean Square Error) decreased by up to 2.37 cm and the RPE (Relative Peak Error) decreased by 22.04% compared to the SWMM alone. When the accuracy of each scenario was analyzed, similar or better accuracy was obtained as far as the parameters were considered. However, the further consideration of less sensitive parameters tends to reduce the accuracy. In this study, it was found that a more efficient simulation in terms of accuracy and calculation time could be obtained when constructing scenarios by considering only highly sensitive parameters. Additionally, when combining two-dimensional (2D) flood analysis with other rainfall events, it can help study real-time flood forecasting in urban areas.

Probabilistic Analysis of Floods from Tailings Dam Failures: A Method to Analyze the Impact of Rheological Parameters on the HEC-RAS Bingham and Herschel-Bulkley Models

The difficulty in determining the rheological characteristics of tailings inside reservoirs as well as their intrinsic variability adds uncertainty to tailings dam failures in flood studies. Uncertainty propagation in non-Newtonian hydrodynamic models stands as a great scientific challenge. This article explores the sensibility of tailings dam breach flood mapping to rheological parameters in Bingham and Herschel-Bulkley (H-B) models. The developed approach was based on the probabilistic Latin Hypercube Sampling of rheological parameters. It was automated to propagate uncertainty throughout multiple hydrodynamic simulations using the HEC-RAS v.6.1 software. Rheological parameter ranges and distributions were based on a broad bibliographic review. Bingham models were revealed to be more sensitive than H-B in terms of simulated min-max area values: for Bingham, flood areas, maximum depths, and arrival times varied by 17.9%, 9.3%, and 8.2%, respectively; for H-B, variations were 25.7%, 5.1%, and 3.9%. However, Bingham was less sensitive in terms of hydrodynamically associated probability: high probability ratios were related to a small range of simulated areas in Bingham, while H-B presented great variability. Finally, for each model, the parameters that affect uncertainty the most were identified, reinforcing the importance of determining them properly. Furthermore, the identified parameter ranges for both models should be valuable for defining variable value boundaries for flood sensitivity tests on specific tailings materials for other case studies. The automated algorithm can be used or adapted for specific tests with other hydrodynamic simulations.

Airborne UAV Remote Sensor Position Accuracy Algorithm in Catastrophes Zones

Sensor payload calibration and FOV are still the most essential parameters in Airborne Remote Sensors for developing quality terrain images in the Remote Sensing field. UAVs are core devices in Airborne Remote Sensing by carrying camera payload for large terrain objects to achieve desired image quality with geographical position provided for different available flight planning algorithms.
 This paper proposes the algorithm to find the exact Geo-coordinates for UAV navigation algorithm viewpoint identification for implementing Airborne Remote Sensing (ARS) to study Landslide Susceptibility Zone as well as application for catastrophe analysis. Terrain Slope and Aspect was considered using Remote Sensing products from ISRO CartoSat and NASA ASTER satellite available in the Digital Elevation Model (DEM) construction to maintain the calibrated angle of vision, field of vision, and land surface image quality.
 This algorithm will enhance the functioning of various available UAV Flight Planning Algorithms to improve the quality of 3D topography images for 3D Modeling as well as Landslide and Flood Prediction and Analysis, as well as provide the position of camera payload and tilting angle for enhanced terrain images.

Physical resilience of riverside cities against floods

Human societies today pay attention to natural disaster control more than ever, yet floods are still among destructive hazards. Researchers are constantly seeking solutions to mitigate the damages associated with floods and increase urban resilience against them. This study explored the assessment of urban physical resilience to floods, rapid recovery from flood shocks, and enhancement of urban functioning over time. This was an applied study using a descriptive-analytical method. The research population consisted of experts in urban affairs. First, the research variables and indices were extracted through the theoretical foundations, and then, validity testing was used to identify the most effective indicators. A review of the research literature showed a lack of consensus on a coherent model for flood damage assessment across different urban zones and the identification of effective indices. Therefore, HEC-GeoRAS (a program for inundation mapping) was used for flood Vulnerability zoning of the Cheshmeh Kileh River Region, Based on this, three zones Vulnerable to floods were determined. The proposed model and its algorithms are structured based on GIS statistical modeling, which accurately zones the urban fabric around the river based on Vulnerability severity and accurately identifies vulnerabilities. This model did not follow the current methods that limit river buffer zones to two categories inside and outside the river's buffer zone; rather investigated the zones based on the Vulnerability severity of urban cover classes (e.g., roads and buildings). The research findings suggest that the conditions of the existing buffer zone deviate from those recommended by the modeling results. Meanwhile, a historical analysis of floods shows that the affected areas match those identified by the software. In all studied zones, the primary cause of the Vulnerability is the absence of surface water drainage networks, non-standard constructions, and road network-related restrictions, which exacerbate the crisis conditions. The existence of large area (coarse-grained) plots can be considered a point of strength in all zones, which presents an opportunity to modify the urban fabric in the future.

Analysis and risk prevention of flooding in high-risk gorges in the city of Arequipa – Perú

La ciudad de Arequipa, la segunda ciudad más importante del Perú, se ve enfrentada a eventos extremos como lluvias de alta intensidad, pero de corta duración que generan inundaciones y crecidas del rio Chili (avenidas de lodo y huaycos). Esta situación agrava la vulnerabilidad de la población asentada en las márgenes de las quebradas posteriormente torrenteras, debido a la poca o nula planificación territorial por parte de las entidades gubernamentales reflejadas cada año en pérdidas humanas y de infraestructuras presentes. La frecuencia de estos eventos va en aumento con el tiempo y es por esta razón que se generan umbrales de precipitaciones extremas para su correspondiente caracterización con un registro de 41 años (1981-2021) con el objetivo de informar sobre la peligrosidad de un fenómeno meteorológico adverso, previsto o en desarrollo. Se utilizó datos de precipitación máxima de 24 horas de las estaciones meteorológicas del SENAMHI (Servicio Nacional de Meteorología e Hidrología del Perú) para obtener el hidrograma líquido para diferentes periodos de retorno con el modelo hidrológico HEC - HMS. También se realizaron estudios de mecánica de suelos para determinar los parámetros reológicos del flujo no newtoniano y luego calibrar a través de eventos históricos con el modelo hidráulico HEC - RAS. Finalmente se elaboraron mapas cartográficos en QGIS para evaluar las zonas de peligro por inundaciones en las torrenteras Del Pato, San Lázaro, Venezuela y Los Incas.