scholarly journals GIS based Flood Vulnerability Studies for Ife Central Local Government Area, Osun State, Nigeria

2020 ◽  
Vol 4 (1) ◽  
pp. 160-171
Author(s):  
V.A. Ijaware
Keyword(s):  
Local Government ◽  
Flood Hazard ◽  
Pairwise Comparison ◽  
Tropical Rainfall Measuring Mission ◽  
Satellite System ◽  
Comparison Method ◽  
Local Government Area ◽  
Landsat 8 ◽  
Flood Hazards ◽  
Flood Vulnerability

Flood has negatively affected Ife Central Local Government Area of Osun State, Nigeria. This work is aimed at mapping the vulnerability of the area to flood. Its objectives addressed the ranking of various natural and artificial factors causing flood, the determination and delineation of vulnerability to flood in the study area. Using remote sensing and GIS techniques, coordinates of flooded sites were acquired with Global Navigation Satellite System receiver; Landsat 8 data were acquired from the USGS website. To map land use, elevation data were acquired from the Shuttle Radar Topographic Mission Digital Elevation Models, soil data was obtained from the Nigerian Geological Survey website, and rainfall data was acquired from Tropical Rainfall Measuring Mission satellit. Using Pairwise Comparison, the various weights of factors constituting flood in the area were acquired. Weighted Linear Combination and Analytical Hierarchical Process was used in producing the flood hazard and flood vulnerability maps. ArcGIS 10.2 Software was used in spatial and attribute data acquisition, processing, and information presentation. The Pairwise Comparison method adopted was validated and observed to have a consistency ration of 0.003. Results obtained show that 9.2% of the study area is highly prone to flood hazards 20.4% is prone to flood hazard and 44.3% is moderately prone to flood hazard. The method adopted correctly identifies all existing flood incidence areas within the flood- prone areas in the hazard map. The maps produced will serve as an effective tool to aid the prevention and mitigation of flood disaster in the flood-prone area.

scholarly journals Flood Vulnerability Mapping of Lagos Island and Eti-Osa Local Government Areas Using a Multi-Criteria Decision Making Approach

2017 ◽  
Vol 1 (2) ◽  
pp. 244-255
Author(s):  
D. N. Olayinka ◽  
H. E. Irivbogbe
Keyword(s):  
At Risk ◽  
Local Government ◽  
Pairwise Comparison ◽  
Spatial Modelling ◽  
Comparison Method ◽  
Mapping Method ◽  
Vulnerability Mapping ◽  
Case Scenario ◽  
Worst Case ◽  
Flood Vulnerability

This study discusses the assessment and analysis of areas vulnerable to flooding in Eti-Osa and Lagos Island Local Government areas of Lagos state, using Geographic Information System (GIS), LIDAR and spatial modelling techniques. These areas require quality assessment of their level of vulnerability to floods, in order to take adequate measures and develop programs that will help prevent the impacts of flooding. A set of indicators influencing flooding, which are elevation, slope, flow accumulation and land use, were identified and used in the study. A vulnerability scale of (1 – 3) was developed, where 1 represents ‘low’, 2 represents ‘moderate’ and 3 represents ‘high’. The indicators identified were reclassified in the vulnerability scale. The flood vulnerability maps, in three different case scenarios, were created using the weighted overlay of the reclassified indicators identified. The weights used are determined by a Pairwise comparison method (Analytical Hierarchical Approach (AHP). The mapping method was implemented in ArcGIS environment. The vulnerability mapping results show that for a normal case scenario, 27.15% of the area have high vulnerability, 49.79% have moderate vulnerability and 23.06% have low vulnerability. However, for a worst-case scenario, 60.01% have high vulnerability, 37.71% have moderate vulnerability and 2.28% have low vulnerability. Buildings at risk and the extent of areas at risk were determined and relevant recommendations were made.

Multi-Criteria Decision Making for Vulnerability Mapping of Flood Hazard: A Case Study of Pune City

2019 ◽  
Vol 2 (1) ◽  
pp. 41-52
Author(s):  
Nitin Mundhe
Keyword(s):  
Decision Making ◽  
Flood Hazard ◽  
Geographical Information ◽  
Multi Criteria Decision Making ◽  
Flood Hazards ◽  
Very High Frequency ◽  
Flood Vulnerability ◽  
Natural Risk ◽  
The Town

Floods are natural risk with a very high frequency, which causes to environmental, social, economic and human losses. The floods in the town happen mainly due to human made activities about the blockage of natural drainage, haphazard construction of roads, building, and high rainfall intensity. Detailed maps showing flood vulnerability areas are helpful in management of flood hazards. Therefore, present research focused on identifying flood vulnerability zones in the Pune City using multi-criteria decision-making approach in Geographical Information System (GIS) and inputs from remotely sensed imageries. Other input data considered for preparing base maps are census details, City maps, and fieldworks. The Pune City classified in to four flood vulnerability classes essential for flood risk management. About 5 per cent area shows high vulnerability for floods in localities namely Wakdewadi, some part of the Shivajinagar, Sangamwadi, Aundh, and Baner with high risk.

The Physiognomy of Flooding and Flood Disasters in Nigeria: Stakeholders’ Perception of Flooding Events of Ogbaru in Anambra State

2019 ◽  
pp. 1-12
Author(s):  
F. O. Ezeokoli ◽  
K. C. Okolie ◽  
A. I. Aniegbuna
Keyword(s):  
Local Government ◽  
Ground Surface ◽  
Flood Disaster ◽  
Local Government Area ◽  
Building Construction ◽  
Flood Hazards ◽  
Anambra State ◽  
Mitigation Action ◽  
Flooding Events ◽  
Structured Questionnaire

Aim: This study evaluates and establishes the nature and characteristics of flooding and flood disaster in Ogbaru. Study Design: It was a survey research, where questionnaires were distributed to heads of the selected households and building practitioners in the study area. Likewise, physical observations were carried out to substantiate the findings of the questionnaire survey. Place and Duration of the Study: The study was conducted in Ogbaru Local Government Area, Anambra State, Nigeria for a period of 2 years. Methodology: Data were collected through structured questionnaire administered to the selected building construction practitioners and occupants in Ogbaru. In addition, interviews and direct observation survey were conducted to substantiate the validity of the questionnaire. Accordingly, a total of three hundred and eighty-four (384) questionnaires were distributed and a total of two hundred and ninety-three (293) questionnaires were completed and returned. This corresponds to a response rate of 76.3%.  Data collected were analyzed using mean score, standard deviation and t-test. Results: The survey found that flooding is a regular phenomenon for the last five years in Ogbaru with a depth ranging from medium to shallow and not more than 1.8 m deep. The velocity of flow is either laminar or moderate but not up to 3m/s in nature while the intensity of flow & destruction significantly varies across the local government area. The flood disaster lasts for more than a month in most areas and moves with floating debris lowering the ground surface and removing refilled earth of the foundation of buildings. Over 90% of the residents of Ogbaru had experienced flood hazards which have affected their houses and those of their neighborhood. Conclusion: The study concluded by recommending that the nature and characteristics of flooding in the study area should be thoroughly examined and considered before any construction/ mitigation action will be deployed in Ogbaru.

scholarly journals Land Use/Land Cover Changes of Ado-Ekiti LGA, Ekiti State, Nigeria Using Remote Sensing Techniques

2021 ◽  
pp. 32-42
Author(s):  
Ajagbe, Abeeb Babajide ◽  
Oguntade, Sodiq Solagbade ◽  
Abiade, Idunnu Temitope
Keyword(s):  
Remote Sensing ◽  
Land Use ◽  
Local Government ◽  
Land Cover ◽  
Water Body ◽  
Local Government Area ◽  
Land Cover Changes ◽  
Landsat 8 ◽  
Land Use Land Cover ◽  
Bare Surface

Land use assessment and land cover transition need remote sensing (RS) and geographic information systems (GIS). Land use/land cover changes of Ado-Ekiti Local Government Area, Ekiti State, Nigeria, were examined in this research. Landsat 5 TM, Landsat 7 ETM+ and Landsat 8 OLI were acquired for 1985, 2000, and 2015 respectively. Image scene with path 190 and row 055 was used for the three Landsat Images. A supervised digital image classification approach was used in the study, which was carried out using the ArcMap 10.4 Software. Five land use/land cover categories were recognised and recorded as polygons, including Built-up Areas, Bare surface, water body, Dense Vegetation and Sparse Vegetation. The variations in the area covered by the various polygons were measured in hectares. This study revealed that between 1985 and 2015, there was a significant change in Built-up areas from 1694 hectares to 5656 hectares. However, there was a reduction in water body from 25 hectares in 1985 to 19 hectares in 2015; there was a severe reduction in the bare surface from 4641 hectares in 1985 to 2237 hectares in 2015. Generally, the findings show that the number of people building houses in the study area has grown over time, as many people reside in the outskirts of the Local Government Area, resulting in a decrease in the vegetation and bare surfaces. The maps created in this research will be useful to the Ekiti State Ministry of Land, Housing, Physical Planning, and Urban Development to develop strategies and government policies to benefit people living in the Ado-Ekiti Local Government Area of the State.

scholarly journals Flood Rate Assessment of the Woyla River Watershed, Aceh Province, Indonesia

2021 ◽  
Vol 10 (2) ◽  
pp. 84-99
Author(s):  
Rifa Alayani ◽  
Sugianto Sugianto ◽  
Hairul Basri
Keyword(s):  
Flood Hazard ◽  
Survey Method ◽  
Flood Hazards ◽  
Flood Vulnerability ◽  
Flood Susceptibility ◽  
Aceh Province ◽  
Collection Data ◽  
Hazard Level ◽  
Hazard Levels ◽  
Very High

This study aims to assess Flood susceptibility and flood hazard levels and obtain the distribution of hazard levels and flood hazards in the Woyla watershed, Aceh Province. This research design generally uses a descriptive survey method and divide into several stages, such as data collection, data processing, data presentation, and delivery of research results. Each determinant of flood-prone areas includes a land slope, altitude, soil texture, drainage, land cover, and rainfall, analyzed spatially utilizing a map. Furthermore, based on the map, the regions are described based on the values that have been divided into classes. The results showed that the level of flood vulnerability in the Woyla watershed was divided into five classes, namely; the non-vulnerable class with an area of 14.88 Ha / 0.01%, low prone with an area of 90,731.62 Ha / 35.45%, medium with an area of 57,120.35 Ha / 22.32%, high with an area of 44,918.15 Ha / 17.55%, and very high with an area of 63,151.72 Ha / 24.67%. Also obtained a map of the distribution of flood hazard areas, the Woyla watershed area is divided into five classes, namely; the very light class with an area of 179,146.15 Ha / 70.00%, mild with an area of 32,868.84 Ha / 12.84%, moderate with an area of 20,129.93 Ha / 7.87%, danger with an area of 6.007. 29 Ha / 2, 35%, and very dangerous with an area of 17,784.51 Ha / 6.95%. The level of flood vulnerability in the Woyla watershed is dominant in West Aceh Regency, which is in the very high and high category classes with a total area of 56,876.65 Ha and 23,527.40 Ha. Meanwhile, the level of flood hazard in the Woyla watershed is also more dominant in West Aceh Regency than falls into the most dangerous and dangerous class category with a total area of 17,784.51 Ha and 6,007.29 Ha. With the largest part in the very light class at the flood hazard level of 179,146.15 ha.

scholarly journals Monitoring Supraglacial lakes Formation and Risk of Outburst Flooding in the Himalayan Cryosphere of Pakistan

2020 ◽  
Vol 9 (1) ◽  
pp. 52-67
Author(s):  
Arshad Ashraf ◽  
Manshad Rustam
Keyword(s):  
Flood Hazard ◽  
Fold Increase ◽  
Hydrodynamic Process ◽  
Landsat 8 ◽  
Flood Hazards ◽  
Mountain Ranges ◽  
Supraglacial Lakes ◽  
Hindu Kush ◽  
Dramatic Rise ◽  
Downstream Communities

The dramatic rise in warm temperatures in the Himalayan region has caused the formation and expansion of numerous supraglacial lakes, some of which pose a serious flood hazard for the downstream communities. In this study, we have investigated the risk of flood hazards associated with supraglacial lakes in the Hindu Kush, Karakoram and Himalayan ranges of Pakistan using Landsat 8 OLI (Operational Land Imager) data of 2013 and field observations. Among the total of 438 supraglacial lakes, the majority were identified in the Karakoram (378) followed by the Hindu Kush range (39). The concentration of lakes was high within 3500-4000 m elevation (168) followed by 4000-4500 m elevation range (116). The lakes had shown more than a two-fold increase during the 2001-2013 period in the three mountain ranges. The increase in lake number was pronounced over valley glaciers likely due to increasing hydro-glacial activity under changing climate. Two types of supraglacial lakes were identified based on geographic characteristics, for example those rolling over glaciers surface away from the margins (called rolling supraglacial lakes ‘RSLs’) and the lakes found near the margins of glaciers mostly stationary in nature (called static supraglacial lakes ‘SSLs’). Most of the glacial lakes outburst flood (GLOF) events have been observed from SSLs in this region. However, the hydrodynamic process exaggerating the risk of GLOF from supraglacial and englacial lakes needs in-depth research for effective disaster risk reduction in this region in future.

scholarly journals Need Assessment of Farmers in Crop-Livestock Production Systems in Ido Local Government Area, Oyo State, Nigeria

2019 ◽  
Vol 7 (2) ◽  
pp. 177-186
Author(s):  
Sosina Adedayo
Keyword(s):  
Local Government ◽  
Technical Assistance ◽  
Production Systems ◽  
Group Discussion ◽  
Pairwise Comparison ◽  
Sampling Technique ◽  
Livestock Production ◽  
Local Government Area ◽  
Donor Agencies ◽  
Inadequate Nutrition

Agricultural projects and programmes funded by governments and donor agencies often failed to achieve the desired set objective(s) at the system levels. The study tries to assess the existing production practices with a view of coming up with a consensus farmer need in a crop-livestock production system at Ido Local Government Area (LGA). The study used a three-stage-sampling technique to elicit information from 225 respondents. Ido Local Government Area was purposively selected for the study. Three cells were randomly selected for the research, three villages were randomly selected in each cell and twenty-five farmers were selected using the snowball selection technique. The data obtained from the Participatory Rural Appraisal were analyzed using descriptive statistics. The pairwise ranking tool helped in determining the importance of the identified problems from the FGD in the study area. The researcher identified the following problems (Pb) from the focus group discussion; inadequate capital for livestock production (Pb1), poor housing for livestock (Pb2), inadequate nutrition for livestock (Pb3), diseases of crops (Pb4), livestock and predatory attack on crops (Pb5). The pairwise comparison of percentage of Pb1 versus (vs) Pb2 was 80/20%, Pb1 vs Pb3 was 68/32%, Pb1 vs Pb4 was 80/20%, Pb1 vs Pb5 was 12/88%, Pb2 vs Pb3 was 68/32%, Pb2 vs Pb4 was 20/80%, Pb2 vs Pb5 was 20/80%, Pb3 vs Pb4 was 32/68%, Pb3 vs Pb5 was 20/80%, vs Pb4 vs Pb5 was 20/80% respectively. The ultimate farmers’ problem in crop-livestock production systems (CLPS) that needs immediate intervention and technical assistance was inadequate capital as perceived from the responses of the farmers.

scholarly journals Analysis of the Impacts of Urbanisation on Land Cover Change in Gombe Local Government Area, Gombe State Nigeria

2020 ◽  
Vol 03 (12) ◽  
Author(s):  
Bibi Umar Muhammed ◽  
Keyword(s):  
Local Government ◽  
Land Cover ◽  
Supervised Classification ◽  
Spatial Information ◽  
Population Change ◽  
Urban Expansion ◽  
Local Government Area ◽  
Landsat 8 ◽  
Land Cover Types ◽  
Short Period

Like many other Nigerian capital cities of newly created states in the 1990s, Gombe the capital city of Gombe State in the North-eastern geopolitical zone has experienced tremendous change in the land cover which is primarily driven by urbanisation. However, little is known on the extent of this urban expansion, how it has affected other land cover types or the dynamics of demographic change as a function of urban growth in the area. This spatial information is highly needed for effective planning and development. This paper, therefore, attempts to answer these questions by firstly, processing LandSat5 images of 1998 and Landsat 8 images of 2016 both of November of Gombe Local Government Area where the state capital is situated. Image processing is then carried out using the semi-automated classification plugin in QGIS 2.18. A supervised classification scheme was used to classify the 1998 and 2016 Landsat Image scenes into four land cover classes (water bodies, built-up area, bare-surface and vegetation) using the spectral angle mapping algorithm. Secondly, the paper analysed population data of Gombe Local Government Area for the same period to understand the dynamics of population change in the area. Based on the findings, urban land cover type increased from 13.02 Km2 (25.14% of the total land cover) in November 1998 to 25.98 km2 (50.17% of the entire land cover) in November 2016. As a result of this change in land cover, all other land cover types decreased in areal coverage. A Kappa index of 0.82 and 0.81 suggest that that the error margins during the supervised classification process of the 1998 and 2016 Landsat images are relatively small. The implications of rapid changes in land cover and population change in the area over a short period of 18 years on planning and management are also discussed.

scholarly journals Assessing vulnerability for inhabitants of Dhaka City considering flood-hazard exposure

Geofizika ◽  
2020 ◽  
Vol 37 (2) ◽  
pp. 97-130
Author(s):  
Md. Enamul Huq ◽  
Md. Mahabubur Rahman ◽  
Abdullah Al Mamun ◽  
Md. Masud Parves Rana ◽  
Ahmed Abdullah Al Dughairi ◽  
...  
Keyword(s):  
Flood Hazard ◽  
Future Research ◽  
Urban Habitat ◽  
Flood Hazards ◽  
Flood Vulnerability ◽  
Hazard Exposure ◽  
Household Vulnerability ◽  
Individual Household ◽  
Social Environmental ◽  
Future Work

Global flood hazard is gradually increasing. Though it is impossible to avoid them, losses and damage of hazards (e.g., floods, cyclones, and earthquakes) could be efficiently reduced by reducing household vulnerability with appropriate measures. This study aims to quantitatively measure the household vulnerability of flood hazards as a mitigation tool. It also proposed a unique approach to quantify flood-hazard household vulnerability, and shows its application in the flood prone city of Dhaka as an example case. Data were collected from both slum and non-slum areas to cover the entire urban habitat, and to compare their level of flood vulnerability. A total of 300 households were surveyed by structured questionnaire on the basis of five factors (economic, social, environmental, structural, and institutional) of flood vulnerability. The analytical hierarchy process (AHP) was applied to measure individual household vulnerability scores by using the relative weightage of variables and indicators with proper standardisation. Analytical results demonstrated that 63.06% slum and 20.02% non-slum households were highly vulnerable to floods. In addition, this paper determined and assessed responsible factors for household flood vulnerability in Dhaka. For structural vulnerability, results exhibited that 82% of slum households were highly vulnerable, and 95.3% of non-slum households were moderately vulnerable. Socially, 67.3% of slum and 78.7% of non-slum households were moderately and low-vulnerable. The majority of slum and non-slum households (84% and 59.3%, respectively) showed high and moderate vulnerability with respect to economic vulnerability. Moreover, 69.3% of slum and 65.3% of nonslum household institutional vulnerability levels were high. Of slum inhabitants, 63.3% were environmentally at high risk, and 78% of non-slum habitats were in the low-vulnerability category. However, as an effective tool to measure location-specific vulnerability, it is applicable for the measuring vulnerability of other cities in the world with proper customisation. On the basis of this study, future research could be conducted with more factors, variables, and indicators of human vulnerability to natural or artificial hazards/disasters. Future work may provide a better reflection of the vulnerability status of single/multiple hazard(s)/disaster(s).

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