Flood Height Research Articles

Spatial Assessment of Elevation-based Flood Risk Level of Communities and Mitigation Measures in the Wetlands Areas of Rivers and Bayelsa States, Niger Delta Region, Nigeria

The study examined the spatial assessment elevation-based flood risk level of communities and mitigation measures in the wetlands areas of Rivers and Bayelsa States, Niger Delta Region, Nigeria. The study made use of the elevation data from the Shuttle Radar Topographic Mission, flood height and tidal inundation data to determine the flood risk levels of communities in the study location. Similarly, 400 copies of questionnaire were administered to the residents from the wetland communities using random sampling technique. Descriptive and inferential statistics were used for the analysis. Findings revealed that majority of the coastal region in the study area is generally low lying and highly exposed to flood event. Results also showed that most communities in the Ogba/Egbema/Ndoni Local Government Areas are very highly exposed which included Ahoada, Azagbene, Eben, Kpopkie, Owenegbene, Bisagbene, Ekeni among others while the very risk exposed communities included Okpogo, Ebubu, Aboigbene among other. Findings showed that damage compensation and government relief funds were the major ways used to tackle the negative impact of flood. The popular methods of flood abatement in the study area were restoring meanders in brooks and rivers and coastal wetlands protection. The study concluded that many communities in the coastal parts of Rivers and Bayelsa States in the Niger Delta Region of Nigeria are highly prone to flood risk. The study recommended among others that the use of dam for flood abatement and prevention should be adequately established in the study area; and apart from embankment, other flood defense and control measures such as flood barrier, mobile flood wall, coastal sand supply, bypasses to safeguard wetlands, connect rivers to existing lake, dredging rivers, and river bed widening should be adequately put in place to reduce the levels of flood impact in the study area.

A GIS-Based Index of Physical Susceptibility to Flooding as a Tool for Flood Risk Management

The identification and classification of flood-prone areas comprise a fundamental step in the Flood Risk Management approach, providing subsidies for land use planning, floodproofing policies, the design of mitigation measures and early warning systems. To address this issue, a frequently used preliminary tool is the flood susceptibility mapping of a region using a range of widely available data. Therefore, the present study introduces an index-based approach able to qualitatively assess flood-prone areas, named Physical Susceptibility to Floods Index (PhySFI), based on a multi-criteria decision-making method and developed in a GIS environment. The methodology presupposes a critical discussion of variables commonly used in other flood indexes, intending to simplify the proposed representation, and emphasizes the role of the user/modeler. PhySFI is composed of just four indicators, based on physical parameters of the assessed environment. This index was developed and first applied in the city of Rio de Janeiro, as part of the Rio de Janeiro Climate Change Adaptation Plan. The validation process was based on a comparative analysis with flood extent and height simulated by the hydrodynamic modeling of four watersheds within the study area, with different urbanization processes for each one. The results indicate that the index is a powerful preliminary tool to assess flood-prone areas in coastal cities.

Silver lining of the water: The role of government relief assistance in disaster recovery

Combining three datasets, the Australian Longitudinal Census Panel of 2006 and 2011, engineering data on flood-water height, and administrative data on government relief assistance, we investigate whether and how the government’s post-disaster relief payments helped the economic recovery from riverine floods that struck the state of Queensland in Australia in 2010/11. Using a difference-in-differences methodology that compares the flooded areas with unflooded zones within Queensland whereby the flooded zones differed in their levels of flooding and the government’s relief assistance, we find that the government’s disaster relief assistance was effective in economic recovery, having led individuals residing in flooded areas with average flood height to experience a 3.4 percent rise in (self-reported) income following the disaster, relative to those individuals living in unflooded areas of the state. Our findings are robust to a battery of sensitivity tests, including migration, parallel trends, spatial spillovers, and possible confounders.

Study on the applicability of sponge city concept to flood resilient in Sri Lankan cities: Boralesgamuwa and Sub Urban Areas

In the last few decades, climate change and urbanization have made natural disasters worse all over the world. This has increased the likelihood of flash flood disasters. The purpose of this research is to determine if the six key processes (retention, detention, infiltration, purification, storage, and drainage system) of the China sponge city concept have been accounted for in the projects carried out to construct flood-resilient towns in Sri Lanka, as well as the influence of flood mitigation. This research has identified projects that have adapted the concept's main processes by reviewing the report of the Weras Ganga Development Plan, conducting key informant interviews, and a field survey. As a result, flood height is reduced in Boralesgamuwa and sub-urban areas. But some stages are missed because the SCC is not applied as a concept to flash flood control projects in Sri Lanka.

EVALUATING THE PHYSICAL VULNERABILITY OF PUBLIC SCHOOL BUILDINGS AGAINST FLOODING IN METRO MANILA, PHILIPPINES

Vulnerability analysis has always been an integral part of disaster risk assessment. This study aims to assess the physical vulnerability of public school buildings against flooding. It discusses the vulnerable elements or attributes, the extent of damages incurred during flood events, the damage response, and the future steps that must be taken to increase flood resiliency. The study used empirical data collection using semi-structured interviews to characterize the common types of public schools and to collate the damage responses. Quantity surveying was performed to measure the amount of damages related to different flood depths. Structural damages to public school buildings are not expected for flood heights ranging from ground level up to ten (10) m. However, damages are incurred by building finishes and fixtures. Floors, walls, and septic system are cosmetically damaged. Vulnerable components include wooden elements like doors, cabinets, blackboards and ceiling, and electrical fixtures such as wiring, lighting, outlets, switches, and fire alarm system. Comprehensive vulnerability description of public school buildings were represented as curves of flood depth vs. damage index. The damage ratio decreases as the number of floors increase. Maximum damage to one-story building is 23.6% while at 15.02% for four-story school building. This study is an attempt to promote further research of the subject matter in developing countries towards flood resiliency in the built environment.

Dam Break Analysis of Sermo Dam

Sermo Dam is located in the Special Region of Yogyakarta and serves multiple purposes including providing drinking water, supplementing irrigation systems in the Kalibawang area, and flood control. According to data published by the World Commission, 60% of mitigation measures taken to overcome the impact of dam structure failures are unsuccessful. The simulation of dam failure serves as a crucial aspect of flood mitigation plans and strategies because it is more destructive than natural flood waves. This research used HEC-RAS 5.0.7 to examine the flood inundation mapping and simulate dam failure in two dimensions. However, Dam Break Analysis was adopted to provide a Dam Emergency Action Plan Guide to guide managers and the community. The overtopping scenario was adapted to model the failure of the Sermo Dam based on the frequent occurrence of heavy and extreme precipitation in the affected area. Data were analyzed using unsteady flow and PMF discharge with peak inflow discharge of 1276.6 m³/s, which result in an inundation area of 9394 hectares and a maximum flood height of 17 m. Dam failure-induced floods tend to potentially affect eight sub-districts including Kokap, Pengasih, Sentolo, Wates, Panjatan, Galur, Lendah, and Temon. The piping scenario is also considered based on the potential damage that tends to occur. In the piping scenario, the biggest flooding area was 5112 hectares with a maximum flood height of 13 m. About six sub-districts are potentially affected by dam failure-induced floods with Kokap and Sentolo being excluded from the list. Therefore, it is crucial to establish early warning systems and infrastructure to mitigate disaster risks. The results of this research can also inform evacuation planning, damage estimation, and post-flood rehabilitation efforts in the affected areas.

Analysis of Interaction Between Atmosphere and Sea Using The Delft3D Hydrodynamics Model for Mapping Coastal Flood Zone at Belawan Port and Coastal

Belawan port and coastal areas were also not spared from the impact of the tidal flood. This study aims to determine the performance of the Delft3D hydrodynamic model in simulating sea level and waves in tidal floods at Belawan port and coastal area. Final operational global analysis data, MSLP data from NOAA/NCEP, and tidal data from ECMWF were used to run the Delft3D model. The model output was verified by using tide gauge observation data from BIG (Geospatial Information Agency). This research resulted in a mapping of areas affected by tidal flooding in the Belawan port and coastal area by analyzing the interaction between atmosphere, consisting of wind speed and direction parameters and sea parameters in the form of significant wave height. Based on the results of the Delft3D verification with observation data, the average error value is 23.5 cm and the coefficient of correlation is 0.93. This shows that the Delft3D model is quite good at simulating tidal flood heights in the Belawan port and coastal area. Based on atmospheric analysis, it does not really affect the increasing wave height. The influence is given by significant sea wave height, which can increase the height of tidal floods.

Study of flood mitigation system for improving the resilience of pluvial flood control of south Jakarta. (Case study: Ciledug raya, Cipulir.)

Flooding is the inability of the channel capacity to accept stormwater so that it overflows into the surrounding area. The main problem of flooding in Jakarta is not in the main channel but in micro drainage which is commonly known as pluvial flooding. This research was conducted to increase resilience (reduce the risk of flooding) by making a device that is able to handle floods that can reduce the height and time of flooding in a location where flooding occurs. Floods cause damage. The parameters that are very important in determining the damage are inundation height and inundation duration. The methodology used in this research is to combine early warning system and emergency response based on hydrology engineering, hydraulics engineering and data science. The approach taken is to use an emergency response using the help of an early warning system. The emergency response used in this study is based on a mobile pump and its equipment and power that can be moved at any time. The emergency response is to use an early warning by predicting the microphysical symptoms of clouds that occur in the atmosphere. Emergency response is needed to cooperate together with early warning system in pluvial flooding problem. Unifying early warning system and emergency response system that this research called flood device is able to reduce the depth and duration of inundation.

250 years of flood frequency and discharge in an ungauged Corsican mountain catchment: A dendrogeomorphic reconstruction

The primary goal of paleoflood hydrology is to estimate the frequency and magnitude of past floods. Botanical evidence, and particularly scars on trees, has been used repeatedly as paleostage indicators to reconstruct peak discharges and flood height. Yet, these reconstructions depend on the presence of visible scars on tree stems which tend to be masked as trees grow older. Here, we estimated flood magnitude using an alternative approach based on growth disturbances in tree-ring series, tree positions and the minimal discharge necessary to submerge the root collar of a tree as estimated by hydraulic modeling. We tested the reliability of this newly developed approach by using the traditional scar-based reconstruction as a benchmark. To this end, we sampled 60 trees showing evidence of flood damage on their stems along a 787-m long segment of the Asco river (Corsica, France). Based on 440 growth disturbances dated in tree-ring series, we reconstructed 28 floods between 1759 and 2020 and 18 during the 20th century. Using the two-dimensional Iber hydraulic model and detailed topographic data of the study site obtained from UAV imagery, we estimated that peak discharges of the 28 reconstructed events ranged between 10 and 210 m3s−1, with 200 m3s−1 being considered as the threshold for extreme floods. Not only do the scar-based and root collar submersion approaches yield similar results, findings are also clearly in line with the sparse information available from historical archives and short gauge station records on past floods. The unprecedented length and depth of the record presented here opens new avenues for climate change and flood impact research.

Empowerment of elementary school teachers on Psychosocial Structured Activities (PSSA)

Natural disasters (floods) can cause psychological impacts and potential public health hazards. Children carrying out daily activities will be disturbed, including learning, fear, and remembering the flood under normal conditions. Children need mental health and psychosocial support, which are essential in creating and supporting states that allow optimal growth and welfare of children in disaster situations. Deket Sub-district, one of the sub-districts in Lamongan Regency, is a frequent flood. Sidomulyo Village has the highest flood height, with water levels between 15 to 37 centimeters in 2022. SDN Sidomulyo 1 is one of the schools affected by this annual flood. This activity aims to increase elementary school teachers' knowledge and skills in providing Psychosocial Structured Activities (PSSA) through empowering elementary school teachers. The method used is the first stage: training elementary school teachers, the second stage: assisting elementary school teachers in carrying out PSSA for elementary school students, and the third stage: is evaluation and follow-up plans. The teachers and students were enthusiastic and active in participating in the various stages of the activity. There is an effect of training PSSA on the level of teacher knowledge (p = 0.014), and all teachers have good skills after being given training and mentoring.

The catastrophic flood of the Neva, September 10 (21), 1777. So, in what feet it was measured…

The height of one of the most outstanding floods of the Neva on September 10 (21), 1777 is practically not captured on the walls of buildings and structures in St. Petersburg. In this context, the leveling catalog, which reflects more than 700 height marks of this flood, and plans with the location of these marks within St. Petersburg, seems to be absolutely unique and very relevant. The author of the catalog is Friedrich Wilhelm Bauer, quartermaster general, surveyor, cartographer. Work on leveling the flooded urban areas was carried out at the behest of Catherine II. In the leveling catalog of F.V. Bauer notes that the maximum height of the water in the flood of 1777 reached 10 feet 3 inches and that it was measured from the ordinary of the Admiralty footstock. To measure excess F.V. Bauer used the French linear measure, which made it possible to recalculate the maximum flood height to a value of 333 cm.

Assessment of the effect of land use and land cover (LULC) change on depth runoff: Case study of Skikda floods event

Land use and land cover changes in coastal cities can influence drainage sys-tems in ways that affect surface overflows and the infiltration potential of a land surface, making flooding one of the drivers. This research aims to demonstrate the spatiotemporal dynamics of LULC and their combined impact on rainfall and flood height in Skikda, Algeria. The research uses remote sensing (RS) and geographic information systems (GIS) to determine the type and location of LULC changes in Skikda. The supervised classification methodology used the maximum likelihood technique (MCL). Changes were identified in five categories: built-up areas, green spaces, bodies of water, agriculture, and vacant land. In Q-GIS 3.28.2, Landsat 4-5 (TM) data from 1984 and 2004 and Landsat 8-9 (OLI)/TIRS data from 2019 were used based on the United States Geological Survey (USGS). The results show that the impervious built-up area has changed significantly (44.01%) due to massive urbanization and rapid industrialization, which would affect heavy rainfall activity and increase flood height due to the intense imperviousness of the affected soil (from 27% to 44%). The precipitation and flood height were examined and compared with observations to investigate the impact of the LULC model modification during the flood. The comparison of three flood events (1984, 2004, and 2019) revealed that the change in the LULC model is the main factor increasing flood risk in the study area. This study demonstrates the importance of considering temporal changes in land use, land cover, rainfall, and flood height when mapping floods in urban cities.

곡저추출 방법의 비교분석을 통한 산지유역 곡저추출 방법 제안

The mountain catchments where deep valley networks develop continuously are the main places for agriculture and forestry activities. Understanding the geomorphological characteristics of the valley is primarily needed for managing the natural landscapes in mountain catchments. With respect to the characterization of valley geomorphology, delineating the valley bottom is the most fundamental step. However, previous studies on valley bottom extraction focused on wide and unconfined valleys; they excluded colluvial valleys in headwater catchments. Here, we evaluated the suitability of two methods widely used to extract valley bottoms, specifically applying to a mountainous catchment where colluvial valleys dominate. Our results demonstrated that the Valley Confinement Algorithm (VCA) that delineates valley bottoms by adjusting flood height was more suitable than the Geomorphons-based method that extracts valley bottoms according to the topographic patterns corresponding to valley bottom morphologies. It is mainly because the Geomoprhons-based method should be applied differently to each valley type. In contrast, the VCA applies consistently to the whole area of the study catchment. The extracted valley bottom width is proportional to the power of the drainage area in this study area. In particular, the valley bottom width of fluvial valley increase more rapidly than that of colluvial valley.

Evaluation of Inundation Probability and Inundation Depth through Rainfall–Runoff Analysis

Because of their enclosed nature, underground spaces are more vulnerable to flooding than above-ground structures. As a result, flooding disasters have the potential to cause widespread casualties. Major domestic plan manuals such as ‘Waterproof Standards Plan Manual for Underground Space Flood Prevention’ suggest that the expected flood height is determined and measures are established to ensure safety for underground facilities located in areas where flooding is expected, but no clear methods and standards are presented. In this study, an inundation prediction chart was prepared by performing a one-dimensional (EPA-SWMM) model analysis using the probability rainfall, respectively. Then, data on the depth of inundation where the underground facility is located were extracted using a two-dimensional (FLO2D) model analysis. Using inundation depth and weather data, the probability of inundation for underground facilities and the expected inundation height were quantitatively evaluated through @RISK. Based on the quantitative assessment, it was determined that there was a 7.7% possibility of inundation in an underground space in the case of a 2 h time frame (average inundation depth: 0.1557 m), and a 13.3% possibility in the case of a 3 h time frame (average inundation depth: 0.1655 m). It would be possible to contribute to the development of countermeasures and manuals for underground space flooding using the quantitative assessment described above.

Фитоценотическая активность видов рода Rumex L. на пойменных и суходольных лугах в Брянской области

In the article the phytocoenotic activity of species of the genus Rumex L. in the space of 5 syntaxa of meadow vegetation in the Bryansk Region assessed. Based on geobotanical materials collected in 2018–2022 two new associations and one subassociation were established, for which high activity of Rumex acetosella and R. thyrsiflorus was revealed. The maximum activity (V3–5) of R. acetosella is characterized for the ass. Koelerio delavignei–Festucetum rubrae Rumex acetosella var., R. thyrsiflorus – the ass. Trifolio arvensis–Rumicetum thyrsiflori (V1–5) and the ass. Kadenio dubiae–Rumicetum thyrsiflori (V5). R. acetosella reaches the highest abundance-coverage on dry and poor soils, while R. thyrsiflorus naturally increases the abundance-coverage under more mesophytic conditions. High activity of R. acetosella and R. thyrsiflorus was revealed in grass plant communities in xerophytized river floodplains. This change in the moisture regime against the background of a reduction in the duration and height of floods, as well as the lack of haymaking and grazing in floodplain locations in recent decades, contributed to an increase in the activity of the studied species. In the future, if the trend towards xerophytization of the floodplains persists, we can expect the stable positions of these species to remain in meadow grass stands.

Risk Assessment for Critical Flood Height of Pedestrian Escape in Subway Station

The escape of pedestrians in the subway station is hampered by floods created by heavy rain. In order to explore the critical flood level in a subway station so that pedestrians can escape safely, the case study of the Mingxiu Road subway station in Nanning, China, was conducted using numerical simulation techniques. In total, 30 groups of sample pedestrians with different walking speeds and numbers were randomly generated by the Monte Carlo method, and 3D simulation software was used for escape simulation. The simulated escape data were put into the SVM model, and the maximum pedestrian capacity and minimum speed of pedestrians were solved successfully with different conditions of the Mingxiu Road subway station. Then, a 1:1 contour model of the pedestrian was constructed to simulate the flood resistance of the pedestrian escaping at the minimum speed. The flood resistance and the friction force between the pedestrian and the ground were compared to calculate the critical escape flood level height, and the critical escape flood level height of an adult, child, and elder was 87.4 cm,75.5 cm, and 83.0 cm, respectively.

Assessing flood risks and the coping strategy: a community adaptation in floodplain areas at Beaufort district in east Malaysia

Floodplains have become increasingly populated areas throughout Malaysia as shown in the case of Beaufort district situated in the state of Sabah at East Malaysia. This area is now exposed to flood hazards due to the rise of new settlements. Nonetheless, the commpunity in the district has managed to survive and thrive with the prevalence of flood hazards. The aim of this study is to identify the risk of loss level faced by affected communities in the area as well as the coping strategies practised during floods. A survey consisting of 241 heads of households in four villages was conducted in Beaufort. The raw data was analysed using the chisquare, mean score and frequency. The study outcomes reveal that there are various risks of loss present in all villages such as the risk of death (RD), the risk of injury (RI), the risk of property loss (RPL) and the risk of loss of home infrastructure (RLSI). However, the assessed risk levels are low, even at a flood height of 2.5 metres. Two cases in Beaufort, Kampung Bingkul and Kampung Malugus prove that the accessibility of disruption risk remains low with the same flood height level. The affected communities have traditionally developed coping strategies for flood hazards such as owning a boat or building houses on stilts and attics. The research outcomes can assist relevant local authorities to improvise policies related to flood management in high-risk floodplain areas.

The presence of peat and variation in tree species composition are under different hydrological controls in Amazonian wetland forests

AbstractThe peat‐forming wetland forests of Amazonia are characterized by high below‐carbon stocks and supply fruit, fibres and timber to local communities. Predicting the future of these ecosystem services requires understanding how hydrological conditions are related to tree species composition and the presence, or absence, of peat. Here, we use continuous measurements of water table depth over 2.5 years and manual measurements of pore‐water pH and electrical conductivity to understand the ecohydrological controls of these variables across the large peatland complex in northern Peruvian Amazonia. Measurements were taken in permanent forest plots in four palm swamps, four seasonally flooded forests and four peatland pole forests. All trees ≥10 cm diameter were also measured and identified in the plots to assess floristic composition. Peat occurs in eight of these twelve sites; three seasonally flooded forests and one palm swamp are not associated with peat. Variation in tree species composition among forest types was linked to high flood levels (maximum flooding height) and pH: seasonally flooded forests experience high flood levels (up to 3.66 m from the ground surface) and have high pH values (6–7), palm swamps have intermediate flood levels (up to 1.34 m) and peatland pole forests experience shallow flooding (up to 0.28 m) and have low pH (4). In contrast, the presence of peat was linked to variation in maximum water table depth (i.e. the depth to which the water table drops below the ground surface). Surface peat is found in all forest types where maximum water table depth does not fall >0.55 m below the ground surface at any time. Peat formation and variation in tree species composition therefore have different ecohydrological controls. Predicted increases in the frequency and strength of flooding events may alter patterns of tree species composition, whereas increases in drought severity and declines in minimum river levels may pose a greater risk to the belowground carbon stores of these peatland ecosystems.

Pemodelan Banjir Rob Wilayah Jakarta Utara Menggunakan Sistem Informasi Geografis

Rising sea levels originating from high tides and inundating land are known as tidal flooding. The cases of tidal floods are increasing day by day, especially in areas directly adjacent to the high seas. One of the areas that are prone to tidal flooding is North Jakarta. This study aims to determine the areas affected by the tidal flood and the extent of the area affected by the tidal flood in the Jakarta City area. This research can be used to take preventive action for residents to face the tidal flood disaster. The tidal flood height modeling was obtained based on the value of Mean Sea Level (MSL), Higher High Water Level (HHWL), and the trend of global rising tides. The result of this study is a map of areas affected by tidal flooding, where the lowest is at an altitude of 0.4 m in Penjaringan and Cilincing. At the height of this tidal flood, the impact was approximately 54 hectares of residential areas, 59 hectares of buildings, and 146 hectares of agricultural activities. The highest area affected by the tidal flood is at an altitude of 1.96 m which inundates the coastal District of Penjaringan, Cilincing, Pademangan, and Tanjung Priok Port. The height of the highest tidal flood impacts 983 ha of residential areas, 493 ha of buildings, and 830 ha of the agricultural sector were inundated. At the height of the tidal flood, which is almost 2 m high, it is necessary to carry out careful disaster mitigation efforts for the local government.

Assessment of Flood Risk and Mapping of Flood Risk Zones in Yenagoa, Bayelsa State, Nigeria

In recent years, most Nigerian cities have experienced several major flood episodes with serious catastrophes. Hence, this study was carried out to assess and map flood risk zones in Yenagoa. The Geographic Information System (GIS) and remote sensing technologies were used in generating and analyzing data to identify the different flood risk zones in Yenagoa. Environmental indices such as flood heights, land elevation and land cover images were analyzed using geo-statistical tools such as map overlay operations to produce a flood risk map. The flood risk map produced and the ground truthing carried out confirmed that the highest flood risk are located within residential areas where about 32% of the built-up area was vulnerable to moderate or high risk of flooding. The study revealed that both natural and anthropogenic factors are responsible for the severe flooding experienced in Yenagoa, especially due to heavy precipitation, elevation of the area, poor waste disposal, and inadequate urban development control amongst other factors. The city was classified into three flood risk zones-high, moderate and low, with about 48% of the area being either at moderate or high risk of flooding. It is therefore recommended that the Ministry of Physical and Urban Development should carryout proper urban development control, which will prevent building on flood plains, wetlands and natural drainage channels.