scholarly journals The Role Of Relative Slope Length In Flood Hazard Mapping Using Ahp And Gis (Case Study: Lam River Basin, Vietnam)

2020 ◽  
Vol 13 (2) ◽  
pp. 115-123
Author(s):  
Ba Dung Nguyen ◽  
Dang Tuyet Minh ◽  
Adeel Ahmad ◽  
Quoc Long Nguyen
Keyword(s):  
River Basin ◽  
Flood Hazard ◽  
Influence Factors ◽  
Drainage Density ◽  
Hazard Mapping ◽  
Gis Technology ◽  
Slope Length ◽  
Factors Affecting ◽  
Relative Slope

In addition to the five main factors affecting the formation of floods including slope, rainfall, drainage density, soil, and land cover, the relative slope length factor has also been considered to be one of the fundamental causes that contribute to flood hazard. The paper analyzes the theoretical basis for choosing the relative slope length criterion when zoning flood hazard in Lam river basin. The important role of this factor was evaluated by the results of the flood risk zoning map established by the method of integrating AHP and GIS technology in two cases: using 5 flood influence criteria and using 6 flood influence criteria. Flood hazard zoning maps for 2 cases were tested with 3 historic floods occurring on Oct 2010, Oct 2013 and Oct 2016. The results showed that the map established with six influence factors is more detailed and accurate than the one created with five factors affecting flood hazard because of the similarity with the reality of that map. The results of the study are applicable to other river basins which their geographical features are similar to characteristics the Lam river basin.

scholarly journals ASSESSMENT OF FLOOD INFLUENCE CRITERIA IN THE LAM RIVER BASIN USING A COMBINED DELPHI-AHP METHOD

2021 ◽  
Vol 13 (3) ◽  
pp. 387-396
Author(s):  
Nguyen DUNG ◽  
◽  
Dang MINH ◽  
Keyword(s):  
Land Cover ◽  
River Basin ◽  
Flood Hazard ◽  
Drainage Density ◽  
Analytic Hierarchy ◽  
Slope Length ◽  
Study Results ◽  
Baseline Information ◽  
And Control ◽  
Relative Slope

Flood is represented as one of the most destructive natural hazards to humankind. Assessing and predicting floods hazard is necessary to offer appropriate solutions for flood mitigation and sustainable environmental management. It is only possible when the main criteria that contributed to creating the flood hazard are pointed out. The purpose of the current research was to choose and attribute scores to all various flood-causing factors in the Lam river basin. Firstly, the Delphi method was applied to the expertbased survey to choose six key parameters that led to the floods, including rainfall, slope, relative slope length, drainage density, land cover, and soil. Then, Analytic Hierarchy Process (AHP) approach is employed as an effective tool to obtain a better understanding of all the factors or indicator contributions in the flood process based on weight given to each of six flood influencing elements. The consistency analyses revealed that the findings were coherent and consistent with a previous study. It is also interesting to notice that rainfall and slope are the most prominent flood occurrence criteria with 45% and 25.5%, respectively. However, the influence of other factors (drainage density, relative slope length, land cover, and soil) is not visible. These parameters are assigned to the small weights and do not have a significant influence on the flood phenomenon. The study results provide baseline information, which needs to be taken into account to mitigate and control floods.

scholarly journals ASSESSMENT OF VULNERABILITY IN AGRICULTURAL LAND IN FLOOD PRONE AREAS AND APPLICATION OF MOBILE SMART PHONE IN PROVIDING FLOOD HAZARD INFORMATION IN LAM RIVER BASIN (VIETNAM)

2021 ◽  
Vol 13 (2) ◽  
pp. 254-264
Author(s):  
Nguyen DUNG ◽  
◽  
Dang MINH ◽  
Bui AN ◽  
Nguyen NGA ◽  
...  
Keyword(s):  
River Basin ◽  
Agricultural Land ◽  
Flood Hazard ◽  
Smart Phone ◽  
Flood Management ◽  
Drainage Density ◽  
Slope Length ◽  
Risk Levels ◽  
High Hazard ◽  
Very High

Floods are considered to be one of the most costly natural hazards in the Lam river basin causing infrastructure damages as well as devastating the affected area and relatively high death toll. So prevention is necessary for shielding lives and properties. The flood management on the Lam River basin has been considering for many years to minimize damages caused by flooding. The flood hazard zoning map is one of the indispensable tools to provide information about hazard and risk levels in a particular area and to perform the necessary preventive and preparedness procedures. The multicriteria decision analysis based on geographic information systems is used to build a flood hazard map of the study area. The analytic hierarchy process is applied to extract the weights of six criteria affecting the areas where are prone to flooding hazards, including rainfall, slope, relative slope length, soil, land cover, and drainage density. The results showed in 91.32 % (20103.83 km2) of the basin located in the moderate hazard zones to very high hazard zones. Accordingly, this study also determined 4 vulnerability levels to agricultural land including low, medium, high, and very high. About 94% of the total area of agricultural land in the basin are classified into moderate to the very high hazard of flood vulnerability. The paper presents a method that allows flood risk areas in the Lam River basin to receive information about flood risks on a smartphone, making them more aware.

Flood hazard zoning in Ngan Sau, Ngan Pho river basin, Ha Tinh province using GIS and analytical hierarchical process

2021 ◽  
Vol 66 (1) ◽  
pp. 198-212
Author(s):  
Minh Dang Thi Tuyet
Keyword(s):  
Flood Hazard ◽  
Hazard Analysis ◽  
Drainage Density ◽  
Gis Technology ◽  
Slope Length ◽  
Hazard Zoning ◽  
Hazard Zone ◽  
Gis Environment ◽  
High Flood ◽  
Reliable Methods

This paper introduces the AHP method integrated with GIS technology to provide information for flood hazard analysis in the Ngan Sau and Ngan Pho river basins. The factors ìnluencing the occurrence of floods in a study area include slope, rainfall, drainage density, soil, relative slope length, and land cover. These data are used for establishing a flood hazard zone map in a GIS environment. The obtained results indicate that the two main causes of flooding are rainfall and slope with weights of 45% and 25.5%, respectively. The resultant map has shown about 82.78% of the total catchment area is having a high and very high probability of flood and areas under high flood hazard only covers 17.22% of the study area. The validation of the flood hazard zone map was conducted based on flood evens in the field. The results showed that the AHP technique and GIS are reliable methods for the assessment of the flood hazard potential, specifically in spare-data regions.

scholarly journals Evaluation and validation of flood hazard zoning using Analytical Hierarchy Process and GIS: A case study of Lam River basin (Vietnam)

2021 ◽  
Vol 66 (4) ◽  
Author(s):  
Ba Dung Nguyen ◽  
◽  
Quynh Nga Nguyen ◽  
Thi Lan Pham ◽  
Thi Le Le ◽  
...  
Keyword(s):  
Natural Disasters ◽  
River Basin ◽  
Analytical Hierarchy Process ◽  
Negative Impact ◽  
Flood Hazard ◽  
Gis Technology ◽  
Slope Length ◽  
The People ◽  
Hazard Zoning ◽  
Hierarchy Process

In recent years, the Lam river basin had suffered various forms of natural disasters such as floods, inundations, windstorms, tornadoes, etc. Among all these, the flood has proved to be the greatest threat to the people and the socio-economic development in the basin. Moreover, it is very frequent as compared to other natural disasters. In view of the fact that such disastrous floods are still occurring in the basin, it becomes a necessity to determine the causes and analyze the components affecting flood. This is important in order to develop an early flood warning system and thus minimize the negative impact of flood in the Lam river basin on the people and the facilities. In this paper, the Analytical Hierarchy Process (AHP) analysis method integrated with GIS technology is used to map flood risk zones in the Lam river basin. The parameters used for the analysis are the main causes affecting the floods. In addition to the 5 most commonly used factors such as slope, rainfall, land cover, soil, and drainage density, this study also includes a new factor - relative slope length to compute a more rigorous and reliable model. The results were compared with the two more methods of flood hazard zoning in the same study area: the method of the main flood caused factor analysis and the method of inheriting, data analyzing, and processing. The results were also validated by the historical flood data of three years 2010, 2013, and 2016.

Flood Hazard Assessment of Bago River Basin, Myanmar

2018 ◽  
Vol 13 (1) ◽  
pp. 14-21 ◽  
Author(s):  
Win Win Zin ◽  
Akiyuki Kawasaki ◽  
Wataru Takeuchi ◽  
Zin Mar Lar Tin San ◽  
Kyaw Zaya Htun ◽  
...  
Keyword(s):  
River Basin ◽  
Hazard Assessment ◽  
Geographical Information Systems ◽  
Flood Hazard ◽  
Disaster Risk ◽  
Geographical Information ◽  
Hazard Mapping ◽  
Flood Hazard Assessment ◽  
Structural Measure ◽  
Inundation Map

Flood hazard mapping is an effective non-structural measure for sustainable urban planning, protecting human properties, lives, and disaster risk reduction. In this study, flood hazard assessment for the Bago river basin was performed. The flood inundation map of the Bago river basin was developed by coupling a hydrological and hydraulic model with geographical information systems. Flood hazard maps with different return periods were developed. The flood hazard map can be utilized to enhance the effectiveness of disaster risk management activities.

scholarly journals Use of HAND terrain descriptor for estimating flood-prone areas in river basins

2021 ◽  
Vol 56 (3) ◽  
pp. 501-516
Author(s):  
Ana Alice Rodrigues Dantas ◽  
Adriano Rolim Paz
Keyword(s):  
River Basin ◽  
Flood Hazard ◽  
Mitigation Strategies ◽  
Drainage Area ◽  
Hazard Mapping ◽  
Morphological Pattern ◽  
River Drainage ◽  
Variable Approach ◽  
The Impact ◽  
Flooded Areas

The flood hazard mapping in a river basin is crucial for flooding risk management, mitigation strategies, and flood forecasting and warning systems, among other benefits. One approach for this mapping is based on the HAND (Height Above Nearest Drainage) terrain descriptor, directly derived from the Digital Elevation Model (DEM), in which each pixel represents the elevation difference of this point in relation to the river drainage network to which it is connected. Considering the Mamanguape river basin (3,522.7 km²; state of Paraíba, Brazil) as the study location, the present research applied this method and verified it as for five aspects: consideration of a spatially variable minimum drainage area for denoting the river drainage initiation; the impact of considering a depressionless DEM; evaluation of hydrostatic condition; effect of incorporating an existing river vector network; and comparative analysis of basin morphology regarding longitudinal river profiles. According to the results, adopting a uniform minimum drainage area for the river network initiation is a simplification that should be avoided, using a spatially variable approach, which influences the amount and spatial distribution of flooded areas. Additionally, considering the depressionless DEM leads to higher values of HAND and to a smaller flooded area (difference ranging between 3% and 99%), when compared with the use of DEM with depression, despite 3.1% of the pixels representing depressions. The use of the depressionless DEM is recommended, whereas the DEM pre-processing by incorporating a vector network (stream burning) generates dubious results regarding the relation between HAND and the morphological pattern presented in the DEM. Moreover, the estimation of flooded areas based on HAND does not guarantee the hydrostatic condition, but this disagreement comprises a negligible area for practical purposes.

Variation of Uncertainty of Drainage Density in Flood Hazard Mapping Assessment with Coupled 1D-2D Hydrodynamics Model

2021 ◽  
Author(s):  
Song-Yue Yang ◽  
Che-Hao Chang ◽  
Chih-Tsung Hsu ◽  
Shiang-Jen Wu
Keyword(s):  
Return Period ◽  
Flood Hazard ◽  
Extreme Rainfall ◽  
Drainage Density ◽  
Hazard Mapping ◽  
Extreme Rainfall Events ◽  
Model Sets ◽  
Density Values ◽  
Rainfall Reduction ◽  
Flooded Area

Abstract Coupled 1D-2D hydrodynamic models are widely utilized in flood hazard mapping. Researchers have explored several uncertainties in flood hazard mapping, but have not addressed the uncertainty of drainage density. Drainage density is equal to total length of the drainage divided by the catchment area. The model sets denser the tributary drainages for higher drainage density values. This study uses a designed case and a real case, Yanshuixi Drainage in Tainan, Taiwan, to assess the uncertainty of drainage density in flood hazard mapping. Analytical results indicate that under the same return period rainfall, reduction in tributary drainages in a model (indicating a lower drainage density) results in an underestimate of the flooded area in tributary drainages. This underestimate causes higher peak discharges and total volume of discharges in the drainages, leading to flooding in certain downstream reaches, thereby overestimating the flooded area. The uncertainty of drainage density decreases with increased rainfall. We suggest that modeling flood hazard mapping with low return period rainfalls requires tributary drainages. For extreme rainfall events, a lower drainage density could be selected, but the drainage density of local key areas should be raised.

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