Flood Hazard Zones Research Articles

Assessment of check dams’ role in flood hazard mapping in a semi-arid environment

This study aimed to examine flood hazard zoning and assess the role of check dams as effective hydraulic structures in reducing flood hazards. To this end, factors associated with topographic, hydrologic and human characteristics were used to develop indices for flood mapping and assessment. These indices and their components were weighed for flood hazard zoning using two methods: (i) a multi-criterion decision-making model in fuzzy logic and (ii) entropy weight. After preparing the flood hazard map by using the above indices and methods, the characteristics of the change‐point were used to assess the role of the check dams in reducing flood risk. The method was used in the Ilanlu catchment, located in the northwest of Hamadan province, Iran, where it is prone to frequent flood events. The results showed that the area of ‘very low’, ‘low’ and ‘moderate’ flood hazard zones increased from about 2.2% to 7.3%, 8.6% to 19.6% and 22.7% to 31.2% after the construction of check dams, respectively. Moreover, the area of ‘high’ and ‘very high’ flood hazard zones decreased from 39.8% to 29.6%, and 26.7% to 12.2%, respectively.

Flood hazard zones using 2d hydrodynamic modeling and remote sensing approaches

Increasing frequency and severity of flooding demands identification of flood hazard zones in Kalilangan, Bukidnon in response to the echoing need of better disaster preparedness via enhancing the understanding and awareness of the public on flood characteristics by integrating the use of two-dimensional hydrodynamic modeling and remote sensing. Flood simulation was carried out in a two-dimensional hydrodynamic model using hydrologic engineering center-river analysis system to derive the flood inundation area and flood depth of Kalilangan, Bukidnon. Thus, it was preceded by pre-processing of the model using software packages of hydrologic engineering center-hydrologic modeling system and ArcGIS along with interferometric synthetic aperture radar–digital elevation model, Manning’s roughness coefficient and precipitation data. Five different rain return flooding scenarios were simulated using rainfall intensity duration frequency data. Three zones of flood hazard were then set as low, medium and high. The result shows that most areas of Kalilangan are within the zones of medium to high hazard with residential buildings as the most flooded type of built-up structures. Flood hazard zone areas could be mapped at an accuracy of 79.51%. Thus, harnessing this potential approach offers cost-effective way of flood preparedness viewing hazard-prone areas with special attention and utmost importance.

Flood hazard mapping using FLO-2D and local management strategies of Dire Dawa city, Ethiopia

Study regionThis study was conducted in Dire Dawa city of Ethiopia, where flood hazard occurs on regular basis. Study focusThe study was conducted with the aim of mapping flood hazard and exploring local flood risk management strategies. As to flood mapping, FLO-2D hydrodynamic model was employed to identify flood prone villages. FLO-2D was chosen for its versatility to use different data sources. To identify local flood management strategies, household survey was conducted on 232 households located in flood prone areas. New hydrological insights for the regionThe final result of flood hazard map identified about 1163 buildings located inside high, medium and low flood hazard zones. The validity of the FLO-2D model versus ground truth was statistically tasted and showed a strong positive correlation. Flood smell, cloud direction, extreme weather and gunshot were identified as the locally used flood early warning strategies. Even if, the local flood risk management strategies have helped to reduce the level of vulnerability at normal condition, the gap is observed when extreme events are recorded. It is highly recommended that the flood hazard map developed for the city and existing flood management strategies are properly utilized for future flood risk planning of Dire Dawa city and its watershed.

Geographic information system and AHP-based flood hazard zonation of Vaitarna basin, Maharashtra, India

Flood is one of the most common natural hazard that take place almost everywhere around the world except the polar regions. Flood damage can be reduced through implementing proper management and policies. Flood is a common hazard in Vaitarna basin, Maharashtra, and occurs once in every 2 to 3 years; it causes severe damage to life and properties. Present days, remote sensing and geographic information system are very comprehensive tools for the assessment of hydrological analysis and hazard management. These tools are also capable to deliver quite an accurate result in a cost- and time-effective manner. Thus, in this paper, an attempt has been made to identify critical zones, which are having a higher vulnerability to the flood in the Vaitarna basin through remote sensing and geospatial approach. Total nine influencing factors, such as elevation, slope, distance from the river, rainfall, flow accumulation, land use, geology, topographic wetness index, and curvature have been assessed individually as well as integrated in GIS software by assigning relative weights through the analytical hierarchy process (AHP) approach. As a result of this study, a final flood map has been prepared and the regions having very high flood potentiality are identified. The resultant map has shown about 20% of the total area in Vaitarna basin is having a very high probability of flood, and these regions are requiring some serious attention of governmental or non-governmental bodies to reduce the flood risk. The analytical hierarchy process (AHP) method proposed in this study is capable to provide an accurate result for flood mapping and can be easily applied to other regions around the world for the management and prevention of the flood hazard.

Drawing lines: FEMA and the politics of mapping flood zones

Flooding is the most common and damaging of all natural disasters in USA, and climate change is exacerbating the problem. Accurate flood maps are critical to communicating flood risk to vulnerable populations, to mitigating and adapting to floods, and to the functioning of the federal flood insurance program. Yet, we know little about how the mapping process works in practice. This article argues that politics can shape the remapping process in ways that leave communities vulnerable. Because mapping takes place within the context of the National Flood Insurance Program, the conversation at the local level often centers on the costs of revising the flood hazard zones rather than the risks associated with flooding. This can lead to less than optimal responses by individuals and communities, and suggests that the USA is not adequately preparing for future climate change impacts.

Geospatial hazard modeling for the delineation of flash flood-prone zones in Wadi Dahab basin, Egypt

Abstract This study delineated flash flood hazard zones leading to vast destruction to infrastructure, property, and loss of life. An integrated approach using remote sensing and geographic information systems was applied to reveal flash flood-prone zones. The study approach evaluated topographic, geologic, and hydrologic factors holistically to assess these hazard zones. The morphometric characteristics of Wadi Dahab sub-basins were supported by topographic, geologic, and hydrologic information. Data from Shuttle Radar Terrain Mission and Operational Land Imager imagery were analyzed to characterize hydrological morphometrics, lithology, soil types, and land use. A Natural Resources Conservation Service model was selected to calculate runoff depth at ungauged watersheds. A spatially distributed unit hydrograph was adopted to create the flow time and runoff velocity. The Flashflood Hazard Model was developed by spatial integration of all contributing factors. An analytical hierarchy process was adopted for the logic ranking of the effective factors. The flash flood hazard map classifies Wadi Dahab basin into five relative hazard zones: very high, high, moderate, low, and very low. The highly hazardous zones are distributed at the downstream of Wadi Dahab basin corresponding to steep topography and Precambrian rocks. The hazard map was validated using the flash flood markers defined from field observations.

ARAHAN KEBIJAKAN MITIGASI PADA ZONA RAWAN BANJIR KABUPATEN LIMAPULUH KOTA, PROVINSI SUMATERA BARAT

Indonesia is a country that has a wet tropical climate, so that about 60 % of the cities in Indonesia is very a hazard to flood. The floods have caused many losses to humans. The purpose of this study is determine the direction of development policy mitigation of flood hazard zones in Limapuluh Kota District, by using GIS analysis with the overlay technique. The indicators used to determine the flood hazard zones are rainfall, slope, landform, soil type, geology, elevation, and land use. Mitigation policy directives using AHP analysis involving 15 experts with conservation criteria, regulations, community capacity. The results showed 6,2 % is a very flood zone. Three main landing to reduce the impact of floods is disaster education, improved socialization in flood hazard zones, and planning of based spatial disaster.

Role of physical settings on increasing flood hazard in Muscat Built-up areas (2007-2015) using GIS

This study aims at evaluating selected environmental attributes of urban development pathways in relation to their impacts on increasing cyclone-related flooding in the Governorate of Muscat for the years 2007, 2010, 2013, and 2015. A probability-weighted flood hazard map for the 2015 urban areas was produced by combining all selected environmental attributes into one probability equation, with each attribute given a weight. The 2015 urban flood hazard map showed that 31.7 km² (8.1% of total urban areas) of the built up area is located in the very high flooding hazard zone, 88.3 km² (22.6% of urban area) is located in the high flood hazard zone, 130.5 km² (33.5% of urban area) is located in the medium flooding hazard zone, and 113.4 km² (29.1% of urban area) and 26.1 km² (6.7% of urban area) located in the low and very low flooding hazard zones. The outputs from this research emphasize the potential of environmental forces to increase flood damages. The findings provide decision makers with spatially-explicit evidences on affected areas for more effective evacuation and rescue plans.

Role of physical settings on increasing flood hazard in Muscat Built-up areas (2007-2015) using GIS

This study aims at evaluating selected environmental attributes of urban development pathways in relation to their impacts on increasing cyclone-related flooding in the Governorate of Muscat for the years 2007, 2010, 2013, and 2015. A probability-weighted flood hazard map for the 2015 urban areas was produced by combining all selected environmental attributes into one probability equation, with each attribute given a weight. The 2015 urban flood hazard map showed that 31.7 km² (8.1% of total urban areas) of the built up area is located in the very high flooding hazard zone, 88.3 km² (22.6% of urban area) is located in the high flood hazard zone, 130.5 km² (33.5% of urban area) is located in the medium flooding hazard zone, and 113.4 km² (29.1% of urban area) and 26.1 km² (6.7% of urban area) located in the low and very low flooding hazard zones. The outputs from this research emphasize the potential of environmental forces to increase flood damages. The findings provide decision makers with spatially-explicit evidences on affected areas for more effective evacuation and rescue plans.

Policy Directives for Sustainable Settlement Development at Flood Hazard Zone in Limapuluh Kota District West Sumatera Province, Indonesia

The flood disaster has caused much harm to human life. Efforts to reduce the losses incurred by the policy directed the development of disaster-based residential areas based. The purpose of determining the direction of the policy of settlement development in the area of flood hazard in Limapuluh Kota District. To determine policy direction using AHP approach by involving 25 experts from related institutions. To determine the sustainability of development using the MDS approach. The result of policy analysis of the development of settlement area in the flood hazard area shows that there are three alternatives, namely a) disaster education; b) increased socialization in the flood hazard zone, and c) disaster-based space planning. In addition, the analysis of the sustainability of the development of residential areas shows that the institutional and legal dimensions are still low. Therefore, it is necessary to have the firmness and consistency of the government in spatial planning.

Mitigation Policy of Flood Disaster in Sungai Penuh Town Province of Jambi, Indonesia

This research is based on the weak role of government in reducing the risk of flood disaster in Sungai Penuh Town appropriately, thus efforts are needed to avoid and decrease this situation, in other word mitigation of flood disaster is needed. The purpose of this study are analyzed the characteristics of area based catastrophic flooding, flood hazard, and flood risk and formulate mitigation policy and direction of flood disaster. The type of research is combined or mixed method. This study using quantitative Method used in determining volcano hazard, the level of vulnerability of the community, volcano risk and the use of qualitative Method used in determining the direction and mitigation policies towards mitigation of flood disaster. Findings research shows two characteristics area are good area that didn’t hazard of flood covering 4872 ha and bad area that cause the flood covering 30403 ha, with three levels of flood hazard are high flood hazard covering 3145 ha, medium flood hazard covering 1726 ha, and low flood hazard covering 30403 ha and three levels of flood risk are flood risk high covering 4872 ha, flood risk medium covering 6395 ha, and flood risk low covering 24008 ha. The high flood harmful for environment and agriculture, due this situation, this research is needed mitigation policy of flood disaster which set up zoning on any flood hazard zone, normalization downstream/ estuaries of river, doing and improving the coordination of government in the cross-sectoral of town and regency, developing the early warning system, and socialitation and provide training/ non-agricultural skills to the society.

Development of Flash Flood Hazard Map in Bima City (NTB) using Analytical Hierarchy Process

Flash flood is one of the hydro-meteorological hazards that often occurs in Indonesia. Some major factors affecting this hazard are high topography and weak soil structure. Every incident of flash flood has caused losses in the form of damage to infrastructure, victims, and the other losses. Therefore, flash flood hazard areas should be mapped so that community and local government can anticipate the event during heavy rainfall. This study developed a flash flood hazard index using a decision-making model, with approach of the Analytic Hierarchy Process (AHP). With this method, four parameters were calculated, namely the distance to the stream channels, slope, cover and soil types. The weight and rank values were assigned to the layers and classes of each layer respectively. A hazard map was obtained using an algorithm that combines factors in weighted linear combinations. The index of flash flood hazard zone with rainfall factor was analysed with sensitivity analysis shows better result since 13 of 16 flash flood points (81.25%) are in high vulnerability to flooding.

Dynamic model of forest area on flood zone of Padang City, West Sumatra Province-Indonesia

The flood disaster has caused many harm to human life, and the change of watershed characteristic is one of the factors causing the flood disaster. The increase of deforestation due to the increase of water causes the occurrence of flood disaster in the rainy season. The research objective was to develop a dynamic model of forest on flood hazard zone using powersim 10.1. In model development, there are three scenarios: optimistic, moderate, and pessimistic. The study shows that in Padang there are about 13 percent of high flood hazard zones. Deforestation of 4.5 percent/year is one cause that may increased the flooding intensity in Padang. There will be 14 percent of total forest area when management policy of forest absence in 2050.

An investigation of Digital Elevation Model (DEM) structure influence on flood modelling

Flood is one of the natural calamities that cause huge losses and damages. Flood hazard zonation has been widely produced to face the impact of the disaster. DEM as the primary data to construct the earth surface has been developed from rough to fine resolution. Aster GDEM v.2 within 1arc spatial resolution has an ability to derived DEM and TIN data as bases river geometrics data. Maximum daily peak discharges used to calculate flood peak discharge. Furthermore, steady flow analysis has been used to produce flood inundation model based on four scenarios with return periods 5yr, 10yr, 50yr, and 100yr. The model results have been validated using UAV flood map in 2016 by means of pixel by pixel operation and the result shows that the vertical variance between grid DEM and TIN data about 0.3 m.

A geographic information system-based approach of flood hazards modelling, Paschim Medinipur district, West Bengal, India.

From the beginning of civilisation, human beings have preferred living on the river banks which have been the most vulnerable areas of flood hazards and consequent disasters. During the monsoon period, in many developing countries of south-east Asia, flood hazards and disasters have been a serious challenge for their development. Most of the rivers exceed their normal channel capacity attaining the flood stage and frequently overflow their banks, causing great havoc to the life and property of the people. Flooding is a very serious problem in many districts of West Bengal. The prime concern of delineation of flood-prone areas is to regulate the land use in the flood-prone areas to restrict damage potential and also mitigate the negative effects of floods on people and the economy. In a regulated way, flood-prone areas are required to be developed. Because, on one hand, it is to be ensured that existing hazard and flood damage potential do not increase and new developmental works become a step towards mitigation of disaster risk. In a perspective view, the demarcation and identification of flood-prone areas of different magnitudes, frequencies and return periods on a large-scale map seem to have great importance. Satellite-derived flood maps from 2007 to 2016 have been applied to form a flood frequency map and the same as a group of flood depth maps has been employed to produce the Flood Damage Map for depth data of flood. Finally, the modelling of flood hazards has been directed by envisaging amalgamation of Flood Depth and Flood Affected Frequency. Then the final flood hazard map amalgamated with population and housing data has been used to ascertain the flood disclosure for these two components. Flood hazard analysis in the study area revealed that 24% of the population has been located in high flood hazard zones, where 39% of human settlements are located in different flood hazard zones.

Spatial Analysis of Land Subsidence and Flood Pattern Based on DInSAR Method in Sentinel Sar Imagery and Weighting Method in Geo-Hazard Parameters Combination in North Jakarta Region

The reclamation program carried out in most cities in North Jakarta is directly adjacent to the Jakarta Bay. Beside this program, the density of population and development center in North Jakarta office has increased the need for underground water excessively. As a result of these things, land subsidence in North Jakarta area is relatively high and so intense. The research methodology was developed based on the method of remote sensing and geographic information systems, expected to describe the spatial correlation between the land subsidence and flood phenomenon in North Jakarta. The DInSAR (Differential Interferometric Synthetic Aperture Radar) method with satellite image data Radar (SAR Sentinel 1A) for the years 2015 to 2016 acquisitions was used in this research. It is intended to obtain a pattern of land subsidence in North Jakarta and then combined with flood patterns. For the preparation of flood threat zoning pattern, this research has been modeling in spatial technique based on a weighted parameter of rainfall, elevation, flood zones and land use. In the final result, we have obtained a flood hazard zonation models then do the overlap against DInSAR processing results. As a result of the research, Geo-hazard modelling has a variety results as: 81% of flood threat zones consist of rural area, 12% consists of un-built areas and 7% consists of water areas. Furthermore, the correlation of land subsidence to flood risk zone is divided into three levels of suitability with 74% in high class, 22% in medium class and 4% in low class. For the result of spatial correlation area between land subsidence and flood risk zone are 77% detected in rural area, 17% detected in un-built area and 6% detected in a water area. Whereas the research product is the geo-hazard maps in North Jakarta as the basis of the spatial correlation analysis between the land subsidence and flooding phenomena.double point.

Flood risk management under climate change: a hydro-economic perspective

Abstract Most developing countries, like Nepal, are expected to experience the greatest impact of climate change (CC) sooner and on a greater magnitude than other developed countries. Increase in the magnitude and frequency of extreme rainfall events is likely to increase the risk of flooding in rivers. The West Rapti River basin is one of the most flood prone and also one of the most dynamic and economically important basins of Nepal. This study elicits the willingness to pay (WTP) from the local people in the basin to reduce risks from possible floods due to CC. The WTP for flood mitigation in different flood hazard zones and flood scenarios were determined using referendum method and a face to face questionnaire survey. From a total of 720 households across all flood zones, a stratified randomly selected sample of 210 households was surveyed. The sample included households from a range of socio-economic backgrounds. The average WTP varied by flood hazard zone and within each zone, by CC-induced flood scenarios. The average WTP of respondents was highest for the critical flood prone zone, followed by moderate and low flood prone zones. Similarly, within each zone, the average WTP increased with increasing flood magnitudes due to CC. The variation of average WTP of respondents in different flood prone zones and scenarios indicate different levels of perceived severity. Moreover, the introduction of the concept of ‘man-day’ or ‘labour-day’ in WTP research is a novel and applicable methodological approach, particularly in the South Asian region. The findings of this study are useful for policy implications for the design of participatory flood management plans in the river basin.

Assessment of flood hazard areas using Analytical Hierarchy Process over the Lower Yom Basin, Sukhothai Province

Flood hazard map is essential tool to assess susceptibility of flood prone area. The present study focuses on an assessment of flood hazard areas in Sukhothai province of Thailand where it has suffered from flood in every year with different extents. Spatial analysis in GIS environment has been applied for the estimation of flood risk zones in which six relevant physical factors have been selected namely, rainfall amount, slope, elevation, river density, land use and soil permeability. The relative importance of physical factors has been compared in pairwise matrix to gain the weight values during the process of Analytical Hierarchy Process (AHP). The flood hazard zones have been mapped according to their weights. It has been found that Muang, Kongkrailat, Khirimat and Sisamrong districts are identified as the high risk zones of flood.

Understanding Disaster Risk and Mitigation Special Reference to Ratnapura District

Ratnapura district has an area of 3,275 square kilometers and a population of 1,082.3. The study area is prone to natural and manmade disasters and most of them are originated from metrological events. The main objective of this study was to understand disaster risks of the study area. The other objectives were to examining risk drivers and mitigation process of the Ratnapura district. The identification of extreme rainfall, flood gage level, disaster related deaths and damages was done based on the data collected from the Departments of Meteorology, Irrigation and Disaster Management of Sri Lanka. Disaster inventory map, disaster vulnerability map and disaster risk map were produced to understand the disaster and the risk associated with GIS technology. Gumbal and SINMAP model developed only for RMC and Elaphatha DSD. 56 present families were recorded flood affected from Ratnapura DSD during 1974 – 2017 years. Inventory map shows Elapatha, Ratnapura and Nivithigala as highly risk areas by flood. Gumbal model shows Ratnapura Municipality is 64.3 percent, and it comes under the high flood hazard zone. During the years 1974 – 2010, 45% recorded deaths by landslide in the Elapatha DSD. 5.62 % areas are unstable in the Elaphatha DSD. Vulnerability map and even more risk map will help priorities to the socio – economic planning, and mitigation process in the Ratnapura District.

Flood Hazard Zone Modeling for Cadastral Plots in Ojców National Park in Poland

The paper presents the stages of development of DTM for fragment of ONP (Ojcow National Park). Model was created in order to illustrate potential flood zones of river Pradnik. In subsequent stages of the development are shown: Basic concepts of subjects taken in the publication, characteristics of research object, methodology of DSM implementation, elements of flood zones and assessment of flooded plots devastation impact on their cadastral and landscape values. The advantage of the method is a low cost and short time of DTM creation based on aerial photographs. Created model has also a relatively high accuracy of elaboration. It is noteworthy that for the area being elaborated independent survey were performed using classical and modern technology methods. The work results will provide a base for further analysis in order to determine the flood zones for mountain rivers. Described problem will be the subject of subsequent papers by the authors.