Flood Risk Assessment Using Geographic Information System Techniques: In Guba Lafto District, North Wollo Zone, Amhara National Regional State, Ethiopia.

2021 ◽  
Author(s):  
Dinku Ebabu ◽  
Fikadu Fufa ◽  
Asnake Boyana ◽  
Getahun Sisay
Keyword(s):  
High Risk ◽  
Flood Risk ◽  
Key Factors ◽  
Weighted Overlay ◽  
Causative Factors ◽  
Prone Area ◽  
Significant Area ◽  
Risk Areas ◽  
Risk Zones ◽  
Flood Prone Area

Abstract Background In Ethiopia, flooding has long been recognized as one of the major environmental perils that often develop into a disaster affecting the lives and livelihoods of people for many years. Assessing flood causative factors and identifying flood risk prone areas are very crucial to minimize the harmful consequences of the hazard on the socio-economic conditions of the environment. Result The causative factors of flooding were developed and converted into raster formats to make them classification-ready. Finally, weighted overlay analysis is used to generate the flood risk areas. Based on key factors, the district was classified in to five-risk classes namely; very low, low, moderate, high and very high-risk Flooding zones. The major finding of the study prevails that, most areas of the district is at low, moderate and high-risk zones accounts 25.58, 61.41 and 12.81% respectively. Conclusion The flood prone area is mainly found in the eastern and southern parts of the study area based on their LULC type, soil characteristics and nearness to rivers. The study demonstrates, a significant area of the district is at a high risk for flooding and hence preliminary measures should be taken with the concerned bodies to reverse the resulting adverse impacts on environment.

scholarly journals Development of Flood Prone Area Map for Igbokoda Township using Geospatial Technique

2017 ◽  
Vol 4 (2) ◽  
pp. 158-178 ◽  
Author(s):  
James R. Adewumia ◽  
James K. Akomolafe ◽  
Fidelis O. Ajibade
Keyword(s):  
Flood Risk ◽  
Vegetation Cover ◽  
Slope Angle ◽  
Landsat 8 ◽  
Stream Network ◽  
Rapid Urbanization ◽  
Risk Zone ◽  
Prone Area ◽  
Risk Zones ◽  
Flood Prone Area

Rapid urbanization has greatly increased the volume of runoff generated in many developed areas and subsequently resulting in flooding. This study evaluated the flood prone area of Igbokoda town in Ondo State and developed a flood risk map to facilitate proper planning and future flood mitigation. Scientific technique of GIS was used to identify flood risk areas within the study area. The Landsat 5 (TM), Landsat 7 (ETM+) and Landsat 8 (LC) images for 1986, 1999 and 2013 coupled with STRM 90 m DEM data of the area were used to identify three categorized risk zones. A total of 339 basins were delineated and stream network on the landscape of this area were carved. Hydrological and vegetation cover analyses were conducted using the satellite imageries obtained from United States Geological Surveys Archive online over the study area for three different epochs 1986, 1999 and 2013. There was a sharp decrease in area of vegetation cover from 1986 (19,630 ha) to 1999 (16,527.36 ha) and in 2013 (12,246.80 ha). The hydrological analysis results revealed that a major part of the residential area within the largest basin delineated was associated with low elevation and high slope angle. The combined stream network and slope of the area were used in developing flood risk zones. Three zones were specified: high, medium, and low flood risk zones. The total area covered by the high risk zone was 28.5615 km2 while the area of the medium and small risk zones were 15.94759 km2 and 31.3619 km2 respectively. It is recommended that an increased awareness on flood risk zone should be created among the populace of Igbokoda to guide them in further development.

scholarly journals A Multi-Criteria Decision Support System in the Analysis of Flood Risk and Vulnerability Mapping in Suleja, Niger State, Nigeria

2019 ◽  
Vol 2 ◽  
pp. 1-7 ◽  
Author(s):  
Nura Khaliel Umar ◽  
Halima Sadiya Abdullahi ◽  
Ado Kibon Usman
Keyword(s):  
Flood Risk ◽  
Hazard Map ◽  
Ahp Method ◽  
Rainfall Distribution ◽  
Weighted Overlay ◽  
Causative Factors ◽  
Priority Weights ◽  
Vulnerability Map ◽  
Hierarchy Process ◽  
Pair Wise Comparison

<p><strong>Abstract.</strong> This study aims at assessing flood risk factors and mapping areas vulnerable to flood in Suleja of Niger State, Nigeria, using Geo-spatial techniques. The method follows a multi-parametric approach and integrates some of the flood causative factors as: rainfall distribution, elevation and slope, drainage network and density, landuse/ land-cover and soil type. The Spatial Multi-Criteria Analysis (MCA) was used to rank and display potential locations, while the Analytical Hierarchy Process (AHP) method was employed using pair-wise comparison to compute the priority weights of each factor. The various layers were integrated in weighted overlay tool in ArcGIS to generate the final vulnerability map (high, moderate and low). The normalized criterion weights were obtained for each factor, and the results shows that, rainfall (34) and slope (31) have the highest influence on flood in the study area. The Consistency Ratio (CR) with an acceptable level of 0.05 was obtained which further validated the strength of the judgement. The factor weights from the AHP were incorporated to produce a Geo-hazard map and it showed that areas that are high vulnerable to flood in Suleja constitute about 37%, while moderate and low vulnerable areas constitute about 45% and 18% respectively. Elements at high risk of flood are those found at the extreme northeast, where elevation is very low, southwest where rainfall distribution is high and on low lying areas along the depressions. Therefore using the Geo-hazard map as a guide, local councils and other stakeholders can act to prepare for potential floods.</p>

scholarly journals Towards sustainable community: Effort to reduce flood risk and increase well-being in a densely populated flood-prone area

2021 ◽  
Vol 930 (1) ◽  
pp. 012096
Author(s):  
L Sedyowati ◽  
G Chandrarin ◽  
G I K Nugraha
Keyword(s):  
Community Involvement ◽  
Flood Risk ◽  
Flood Control ◽  
Local Community ◽  
Well Being ◽  
Economic Benefits ◽  
Prone Area ◽  
Community Effort ◽  
Flood Prone Area ◽  
Almost All

Abstract Dealing with flooding in a densely populated flood-prone area poses complex challenges. Almost all residents realize that living in the area is hazardous. However, they choose to stay there. Therefore, flood risk management should be applied in the area. This study aims to: 1) develop facts of the local community in a flood-prone area in decreasing the flood risk while improving well-being through modifying drainage channels used for fish and vegetable farming; 2) evaluate all benefits of drainage investments include the social and economic benefits. The research method consists of a quantitative approach through the distribution of questionnaires and a qualitative approach through in-depth interviews and field surveys. In this study, a concerted community effort was developed as a design parameter. At the same time, the observation parameters include knowledge of the causes of flooding, knowledge of flood risk, community involvement, and government flood control programs. The results showed that the strength of concerted community effort was significantly influenced by the knowledge of flood risk and the local community involvement. This effort can decrease the flood risk by up to 30% and serve direct financial benefits of IDR 48 million in a year.

scholarly journals Assessment of Flood Risk Map under Climate Change RCP8.5 Scenarios in Taiwan

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 207
Author(s):  
Yun-Ju Chen ◽  
Hsuan-Ju Lin ◽  
Jun-Jih Liou ◽  
Chao-Tzuen Cheng ◽  
Yung-Ming Chen
Keyword(s):  
Climate Change ◽  
High Risk ◽  
Flood Risk ◽  
Spatial Scales ◽  
Disaster Risk ◽  
Decision Makers ◽  
Risk Map ◽  
Climate Data ◽  
Risk Areas ◽  
Flood Risk Map

Climate change has exerted a significant global impact in recent years, and extreme weather-related hazards and incidents have become the new normal. For Taiwan in particular, the corresponding increase in disaster risk threatens not only the environment but also the lives, safety, and property of people. This highlights the need to develop a methodology for mapping disaster risk under climate change and delineating those regions that are potentially high-risk areas requiring adaptation to a changing climate in the future. This study provides a framework of flood risk map assessment under the RCP8.5 scenario by using different spatial scales to integrate the projection climate data of high resolution, inundation potential maps, and indicator-based approach at the end of the 21st century in Taiwan. The reference period was 1979–2003, and the future projection period was 2075–2099. High-resolution climate data developed by dynamic downscaling of the MRI-JMA-AGCM model was used to assess extreme rainfall events. The flood risk maps were constructed using two different spatial scales: the township level and the 5 km × 5 km grid. As to hazard-vulnerability(H-V) maps, users can overlay maps of their choice—such as those for land use distribution, district planning, agricultural crop distribution, or industrial distribution. Mapping flood risk under climate change can support better informed decision-making and policy-making processes in planning and preparing to intervene and control flood risks. The elderly population distribution is applied as an exposure indicator in order to guide advance preparation of evacuation plans for high-risk areas. This study found that higher risk areas are distributed mainly in northern and southern parts of Taiwan and the hazard indicators significantly increase in the northern, north-eastern, and southern regions under the RCP8.5 scenario. Moreover, the near-riparian and coastal townships of central and southern Taiwan have higher vulnerability levels. Approximately 14% of townships have a higher risk level of flooding disaster and another 3% of townships will become higher risk. For higher-risk townships, adaptation measures or strategies are suggested to prioritize improving flood preparation and protecting people and property. Such a flood risk map can be a communication tool to effectively inform decision- makers, citizens, and stakeholders about the variability of flood risk under climate change. Such maps enable decision-makers and national spatial planners to compare the relative flood risk of individual townships countrywide in order to determine and prioritize risk adaptation areas for planning spatial development policies.

scholarly journals Socio-hydrological modelling: the influence of reservoir management and societal responses on flood impacts

2020 ◽  
Author(s):  
Cinzia Albertini ◽  
Maurizio Mazzoleni ◽  
Vincenzo Totaro ◽  
Vito Iacobellis ◽  
Giuliano Di Baldassarre
Keyword(s):  
Flood Risk ◽  
Management Strategies ◽  
Floodplain Management ◽  
Technological Systems ◽  
Flood Impacts ◽  
Operating Rules ◽  
Operation Rules ◽  
Prone Area ◽  
Levee System ◽  
Flood Prone Area

&lt;p&gt;Over the last few years, several socio-hydrological studies have investigated the dynamics of risk generated by feedback mechanisms and interactions between floods and societies, with a focus on either changing reservoir operation rules or raising levees. In this study, we propose a new socio-hydrological model of human-flood interactions that represents both changes in the operating rules of reservoirs and updating of the levee system. Our model is applied to simulate three prototypes of floodplain management strategies: green systems, in which societies cope with flood risk by resettling outside the flood-prone area; technological systems, in which societies cope with flood risk also via structural measures, such as levees; and green-to-techno systems, in which societies shift from green to technological approaches. Floodplain dynamics are explored simulating future scenarios in the city of Brisbane, Australia. Results show that flood risk is strongly influenced by the flood memory of reservoir operators and their risk-awareness levels control the development of communities. Furthermore, scenarios of more frequent and higher magnitude events prove to enhance social preparedness levels in green systems, while technological systems experience much higher losses.&lt;/p&gt;

scholarly journals Analysis of the exposure of Polish lakes to flood risk

2015 ◽  
Vol 15 (1) ◽  
pp. 39-50
Author(s):  
Anna Pasiecznik-Dominiak ◽  
Andrzej Tiukało ◽  
Grzegorz Dumieński
Keyword(s):  
Flood Risk ◽  
Flood Hazard ◽  
Risk Level ◽  
Resilience Theory ◽  
Risk Area ◽  
The Social ◽  
Prone Area ◽  
Extreme Hazards ◽  
Flood Prone Area

Abstract Flooding constitutes one of the main natural hazards in Poland, which causes enormous social, economic and environmental losses. The main causes of the occurrence of floods include intensive rainfall, rapid melting of snow and ice cover, as well as strong gusts of wind from the sea. Based on the resilience theory (resistance, elasticity), which constitutes an efficient tool for the description of the social-ecological system capability or components thereof to mitigate the effects of dangerous events, as well as the capability of reconstructing and adapting the system to new conditions, the authors have analysed the exposure of Polish lakes to flood risks with a probability of occurrence Q0.2%, Q1% and Q10%. In order to determine the level of exposure of lakes to the risk of flooding by flood waters, studies were conducted using the flood hazard and flood risk maps which were developed under the Project entitled “IT System of the Country’s Protection against Extreme Hazards”. The result of the efforts of the group of authors is the determination of the number of lakes, which are located in the flood risk area Q0.2%, Q1% and Q10%, including division into risk level groups (low, moderate and high). The results presented in the paper may constitute a contribution to further, more detailed studies concerning assessment of the vulnerability of Polish lakes located in the flood prone area.

scholarly journals Application of Geographic Information Systems for Flood Risk Analysis: A Case Study from Accra Metropolitan Area

2019 ◽  
Vol 13 (1) ◽  
pp. 81-97
Author(s):  
Alex Barimah Owusu ◽  
Mathias Agbozo
Keyword(s):  
Flood Risk ◽  
Drainage Density ◽  
Low Risk ◽  
Soil Drainage ◽  
Risk Area ◽  
The Public ◽  
Risk Areas ◽  
Risk Zones ◽  
High Flood

Abstract The main objective of the study was to identify high flood risk zones in AMA. The study also used questionnaires to assess local knowledge on what accounts for the high flood risk in their community. Spatial analysis techniques were used to model flood risk based on the following contributory factors; land cover, soil, drainage density, topography and proximity to rivers. The results show that high flood risk areas covered 46.3km2(20%), moderate risk area, 72.9km2(31.6%), low risk area 41.5km2(18%) and very low risk areas, about 6.7km2(2.9%). The high flood risk zones were low-lying areas below 50 meters above sea level and closely associated with poor drainage systems. People perceived not just low-lying areas as a paramount reason accounting for flooding but also very bad waste disposal habit of the public. These offsets the efforts of waste management companies to keep drains free of refuse.

scholarly journals Spatiotemporal Flood Risk Determination and Management for a Large River Basin

2021 ◽  
pp. 92-106
Author(s):  
Nuanchan Singkran
Keyword(s):  
High Risk ◽  
River Basin ◽  
Flood Risk ◽  
Mitigation Measures ◽  
Environmental Damage ◽  
Risk Zone ◽  
Risk Indices ◽  
Risk Zones ◽  
Chao Phraya River ◽  
Very High

The Chao Phraya River Basin (CPRB) of Thailand faces flooding almost every year. The severest flood occurred in the CPRB in 2011 with the highest property damage costs (46.5 billion USD) and the highest casualty (813 deaths). The objectives of this study were thus to (1) determine flood risk indices and categorize them into four risk zones (low, moderate, high, and very high) across 994 sub-districts in the CPRB during the six rainy months (May–October); and (2) propose specific measures for flood risk management for each of the categorized risk zones. The flood risk indices were assessed as the product of two hazard variables (flood levels and monthly cumulative precipitation) and the vulnerability variable (land uses). The findings revealed spatiotemporal variations in flood risk. Spatially, the sub-districts deemed to be in the high or very high flood risk zone were mainly located close to the Chao Phraya River (CPR), where the flood levels reached 1.1 – 4 m in depth; whereas the sub-districts detected in the low or moderate flood risk zone were located further away from the CPR. Temporally, more sub-districts were detected in the high or very high risk zone in September when heavy rainfalls were observed. Specific measures are proposed herein to manage flood risk regarding the categorized zones during three periods. The preventive and mitigation measures should be prepared before flooding; emergency responses should be practically implemented during flooding; and the recovery after flooding should cover both infrastructural and environmental damage and mental/physical illnesses amongst the affected people. Intensive measures are recommended for the sub-districts located in both the high and very high risk zones. These measures may be properly loosened for the sub-districts located in the low and moderate risk zones.

Flood Risk Assessment in Asian Flood Prone Area with Limited Local Data – Case Study in Pampanga River Basin, Philippines –

2016 ◽  
Vol 11 (6) ◽  
pp. 1150-1160 ◽  
Author(s):  
Miho Ohara ◽  
◽  
Naoko Nagumo ◽  
Badri Bhakta Shrestha ◽  
Hisaya Sawano ◽  
...  
Keyword(s):  
Risk Assessment ◽  
River Basin ◽  
Flood Risk ◽  
Evidence Based ◽  
Flood Risk Assessment ◽  
Damage Cost ◽  
Local Data ◽  
Prone Area ◽  
Flood Prone Area

Disaster risk assessment is vital to determining needs for disaster countermeasures and promoting their implementation. However, it is difficult to conduct evidence-based risk assessment in flood-prone areas of Asia due to area-specific characteristics such as limited local data on natural and societal conditions and local lifestyles of persons who have adapted to frequent floods. This paper proposes basic flood risk assessment considering these characteristics and explores a case study conducted in a flood-prone area of the Pampanga River basin in the Republic of the Philippines to verify our method. We surveyed local household members as part of the study to understand local situations, finding that past flood damage cost little thanks to building structures adapted to frequent flooding and to local ways of protecting property during floods. We also found that the use of depth-damage curves developed for urban areas may overestimate anticipated damage expected in future floods when these curves are applied to flood-prone rural areas. For this reason, we propose a method of flood risk assessment for evaluating the societal impact on residents’ lives using observed thresholds of inundation depth by flood simulation, rather than using a method that estimates damage cost. Application of our proposal to the case study area confirmed its applicability and effectiveness in evidence-based planning for reducing flood risk.

scholarly journals Design and implementation of two surveys targeted at describing fouling communities and identifying non-native species within active ports

2020 ◽  
pp. 1-14
Author(s):  
Samuel Holmes ◽  
Ruth Callaway
Keyword(s):  
High Risk ◽  
Native Species ◽  
Survey Methods ◽  
Key Factors ◽  
Fouling Communities ◽  
Robust Solution ◽  
Design And Implementation ◽  
South Wales ◽  
Risk Areas ◽  
Caprella Mutica

Abstract Ports have long been considered ‘high-risk’ areas for the introduction of non-native species (NNS) and should therefore be a focus of NNS monitoring. The industrial nature of active ports can, however, provide various problems when attempting to carry out monitoring programmes. Current methodologies designed to identify NNS and to describe fouling communities have not been developed specifically for use in active ports and can encounter a number of issues when used in these environments. Here, two surveys were developed and trialled within an active port in South Wales, UK, designed to describe fouling communities, identify NNS and overcome some of the major limitations to conducting surveys within ports. Over a 6-month period, fouling communities dominated by solitary ascidians developed in each survey. Seven NNS were identified, mostly species already recorded in the 1950s, including the Mediterranean crab Brachynotus sexdentatus, and the more recently introduced Japanese skeleton shrimp Caprella mutica. Each survey was evaluated independently with respect to key factors, including the ability to detect NNS and practical aspects of using these survey methods in an applied context. We conclude that whilst each survey can function independently, the use of both survey types in conjunction offers the most robust solution to identifying NNS and describing wider fouling communities within active ports. This research has implications for the future monitoring and management of NNS within UK ports.

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