scholarly journals A Model-Based Flood Hazard Mapping on the Southern Slope of Himalaya

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 540 ◽  
Author(s):  
Dibit Aryal ◽  
Lei Wang ◽  
Tirtha Raj Adhikari ◽  
Jing Zhou ◽  
Xiuping Li ◽  
...  
Keyword(s):  
Flood Control ◽  
Agricultural Land ◽  
Flood Hazard ◽  
Monsoon Season ◽  
Peak Discharge ◽  
Hazard Mapping ◽  
Southern Slope ◽  
Management And Development ◽  
Analysis System ◽  
High Level

Originating from the southern slope of Himalaya, the Karnali River poses a high flood risk at downstream regions during the monsoon season (June to September). This paper presents comprehensive hazard mapping and risk assessments in the downstream region of the Karnali River basin for different return-period floods, with the aid of the HEC-RAS (Hydrologic Engineering Center’s River Analysis System). The assessment was conducted on a ~38 km segment of the Karnali River from Chisapani to the Nepal–India border. To perform hydrodynamic simulations, a long-term time series of instantaneous peak discharge records from the Chisapani gauging station was collected. Flooding conditions representing 2-, 5-, 10-, 50-, 100-, 200-, and 1000-year return periods (YRPs) were determined using Gumbel’s distribution. With an estimated peak discharge of up to 29,910 m3/s and the flood depths up to 23 m in the 1000-YRP, the area vulnerable to flooding in the study domain extends into regions on both the east and west banks of the Karnali River. Such flooding in agricultural land poses a high risk to food security, which directly impacts on residents’ livelihoods. Furthermore, the simulated flood in 2014 (equivalent to a 100-YRP) showed a high level of impact on physical infrastructure, affecting 51 schools, 14 health facilities, 2 bus-stops, and an airport. A total of 132 km of rural–urban roads and 22 km of highways were inundated during the flood. In summary, this study can support in future planning and decision-making for improved water resources management and development of flood control plans on the southern slope of Himalaya.

Use of Geo-Informatics in Flood Hazard Mapping: A Case of Balkhu River

2017 ◽  
Vol 13 ◽  
pp. 52-57
Author(s):  
Susheel Dangol
Keyword(s):  
Flood Hazard ◽  
Hazard Analysis ◽  
System Model ◽  
One Dimension ◽  
Hazard Mapping ◽  
Land Area ◽  
Technical Approach ◽  
Barren Land ◽  
Flood Depth ◽  
Analysis System

Flood is one of the striking water induced disaster that hits most of the part of the world. In Nepal also it is one of the serious disasters which affect the study describes the technical approach of probable flood hazard analysis. Segment of Balkhu River within the Balkhu catchment of area 44.37 km2 from Kirtipur gorge to Bagmati confluence was taken as area of study. The total length of the study segment was 5485.89 m. One dimension HEC-RAS (Hydrologic Engineering Center-River Analysis System) model was used for the analysis. The study shows that higher flood depth increases and low flood depth decreases with increase in intensity of flood. Also, huge area of barren land area is affected by flood and few percentage of settlement area is affected by flood indicating the damages to the human lives. Huge area of barren land indicates that in future human lives are more prone to disasters as those lands have gone through planning for future settlement.Nepalese Journal on Geoinformatics -13, 2014, Page: 52-57

Review of Flood Hazards Studies in Nepal

2020 ◽  
Vol 7 ◽  
pp. 24-32
Author(s):  
Buddhi Raj Shrestha ◽  
Raj Kumar Rai ◽  
Saroj Marasini
Keyword(s):  
Risk Assessment ◽  
Flow Model ◽  
Flood Hazard ◽  
Hazard Analysis ◽  
Monsoon Season ◽  
Hazard Mapping ◽  
Flood Hazards ◽  
Journal Articles ◽  
Inundation Mapping ◽  
Flood Disasters

Flood, a common water-induced disaster of monsoon season, is a recurring phenomenon in Nepal. It causes many deaths and injuries besides severe impacts on the vital infrastructures of the nation. This paper reviews the published national and international journal articles related to flood hazard mapping in Nepal. Desinventar database from 1971-2016 shows that Bagmati province and province 2 are more affected than other provinces in Nepal. Here we review the previous studies on flood disasters at the regional and national levels. The results show that most of the papers are based on a steady flow model for inundation mapping and more focuses on hazard analysis rather than vulnerability and risk assessment.

scholarly journals FLOOD HAZARD ASSESSMENT USING PARTICIPATORY APPROACH AND WEIGHTED OVERLAY METHODS

2019 ◽  
Vol XLII-4/W16 ◽  
pp. 153-160
Author(s):  
T. Bibi ◽  
F. Nawaz ◽  
A. Abdul Rahman ◽  
A. Latif
Keyword(s):  
Flood Hazard ◽  
Irrigation System ◽  
Monsoon Season ◽  
Essential Element ◽  
Participatory Approach ◽  
Vital Role ◽  
Hazard Mapping ◽  
Weighted Overlay ◽  
Agricultural Revolution ◽  
The World

Abstract. Unexpected growth of population and urbanization eventually leads towards disasters, might be natural or manmade for instance climate change, the rise in sea level, pollution, landslides, floods, etc. Subsequently, floods are the worst effects of agricultural revolution and comes up as a potential most natural hazard in the world. It couldn’t be stopped but the adverse impact can be minimized through structural and non-structural measures. Flood hazard mapping have a vital role and is an essential element of land use and pre-disaster planning. Moreover, the Earth Observation (EO) data can help to prepare the updated flood hazard maps by distant viewing. Pakistan have one of the greatest irrigation systems of the world and is the sixth largest populous country. However, having such a huge irrigation system is also a threat to overflow in heavy rains. The monsoon season in 2010, the unexpected heavy rainfall caused a massive flood which ultimately destroyed the agriculture, infrastructure in several districts all over the country. District Charsadda was affected severely by both riverine floods and flash floods in 2010. Furthermore, the floodplains of district is occupied by dense population showing the immense need to assess hazard zones to avoid additional losses. In this case study for the catchment area of River Kabul and River Swat, Charsadda, the flood hazard was identified using participatory approach and weighted overlay method. Results depict that more than 80% of the area was inundated during 2010 devastating flood in the UC Agra.

scholarly journals Flood Hazard Mapping by Using Geographic Information System and Hydraulic Model: Mert River, Samsun, Turkey

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Vahdettin Demir ◽  
Ozgur Kisi
Keyword(s):  
River Basin ◽  
Flood Risk ◽  
Flood Hazard ◽  
Human Life ◽  
Hydraulic Model ◽  
Hazard Mapping ◽  
Digital Elevation ◽  
Risk Maps ◽  
Analysis System ◽  
Elevation Model

In this study, flood hazard maps were prepared for the Mert River Basin, Samsun, Turkey, by using GIS and Hydrologic Engineering Centers River Analysis System (HEC-RAS). In this river basin, human life losses and a significant amount of property damages were experienced in 2012 flood. The preparation of flood risk maps employed in the study includes the following steps: (1) digitization of topographical data and preparation of digital elevation model using ArcGIS, (2) simulation of flood lows of different return periods using a hydraulic model (HEC-RAS), and (3) preparation of flood risk maps by integrating the results of (1) and (2).

scholarly journals Flood Hazard Mapping in Residential Area Using Hydrodynamic Model HEC-RAS 5.0

2020 ◽  
Vol 7 (1) ◽  
pp. 25-36
Author(s):  
Muhammad Baitullah Al Amin ◽  
Reini Silvia Ilmiaty ◽  
Ayu Marlina
Keyword(s):  
Flow Velocity ◽  
Hydrodynamic Model ◽  
Flood Control ◽  
Flood Hazard ◽  
Hazard Mapping ◽  
Residential Areas ◽  
Low Level ◽  
Flood Depth ◽  
Two Dimensional Flow ◽  
Hazard Rating

The flood hazard rating is one of the essential variables in flood risk analysis. The identification of flood-prone areas urgently requires information about flood hazard zones. This research explains the method to develop flood hazard map by using hydrodynamic modeling in the residential areas. The hydrodynamic model used in this research is HEC-RAS 5.0, which can simulate the one- and two-dimensional flow regimes. The study area is Bukit Sejahtera and Tanjung Rawa residences located in Palembang City with a total area of about 200 ha, where the Lambidaro River was frequently overflowing caused flood inundation in the area. There are five indicators of flood hazard being analyzed, i.e., 1) flood depth, 2) flow velocity, 3) energy head, 4) flow force, which is the result of multiplication between flood depth and the square of flow velocity, and 5) intensity, which is the result of multiplication between flood depth and the flow velocity. The simulation results show that the flood hazard rating in the study area ranges from high to low level. The zones with a high flood hazard rating are dominated by the area around or near to the river, whereas the further zones have a moderate and low level of flood hazard rating. The flood depth indicator has a more significant influence than the flow velocity on the flood hazard level in the study area. This research is expected can contribute to the development of flood map and flood control methods in advance.

Modelling the flooded area extent at the downstream segment of a small basin through a coupled 1D/2D hydraulic model

2020 ◽  
Author(s):  
Sofia Sarchani ◽  
Ioannis Tsanis
Keyword(s):  
Flood Hazard ◽  
Hydraulic Model ◽  
Peak Discharge ◽  
Precipitation Event ◽  
Hazard Mapping ◽  
Roughness Coefficient ◽  
Extreme Rainfall Event ◽  
Flooded Area ◽  
Lateral Structures ◽  
Small Basin

<p>A high-resolution Digital Terrain Model 5m x 5m, land use characteristics and a validated output hydrograph from an extreme rainfall event were used as input to the coupled 1D/2D HEC-RAS hydraulic model in order to obtain the flooded area extent at the downstream segment of a small basin in the island of Crete. A spatially varying Manning’s roughness coefficient <em>n</em> was used to identify the differences between land coverage for the channel bed and the floodplain. Lateral structures were designed along the left and right overbanks of the stream, connecting the 1D stream flow with the 2D flow areas. The weir coefficient, used to convey the flow above the lateral structures, was also chosen for model validation in the control cross section. Detailed flood hazard mapping at the peak discharge was produced, along with the flood depths at times before and after the heavy precipitation event, in order to obtain the time evolution of the flooded area extent. The results obtained by the 1D hydraulic model are limited in their 2D lateral output that is crucial to the floodplain extent. The 1D/2D provides more detailed output concerning the flood extent at the peak discharge, as well as the maximum water depths and velocities at every grid point of the computed mesh. Defining accurate flood inundated areas is of utmost importance in civil protection agencies in order to initiate a proper early flood warning. At the same time, each EU Member State country is required to produce flood hazard maps according to EU Floods Directive at the river basin level. These 1D/2D simulation results can be beneficial in the aforementioned requirements for low probability extreme floods’ basin management.</p>

scholarly journals Flood Hazard Mapping of Rivers in Snow- and Glacier-Fed Basins of Different Hydrological Regimes Using a Hydrodynamic Model under RCP Scenarios

Water ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 2806
Author(s):  
Huma Hayat ◽  
Muhammad Saifullah ◽  
Muhammad Ashraf ◽  
Shiyin Liu ◽  
Sher Muhammad ◽  
...  
Keyword(s):  
21St Century ◽  
Flood Hazard ◽  
River Basins ◽  
Flood Damage ◽  
Hazard Mapping ◽  
Rcp Scenarios ◽  
Digital Elevation ◽  
Late 21St Century ◽  
Analysis System ◽  
Elevation Model

The global warming trends have accelerated snow and glacier melt in mountainous river basins, which has increased the probability of glacial outburst flooding. Recurrent flood events are a challenge for the developing economy of Pakistan in terms of damage to infrastructure and loss of lives. Flood hazard maps can be used for future flood damage assessment, preparedness, and mitigation. The current study focused on the assessment and mapping of flood-prone areas in small settlements of the major snow- and glacier-fed river basins situated in Hindukush–Karakoram–Himalaya (HKH) under future climate scenarios. The Hydrologic Engineering Center-River Analysis System (HEC-RAS) model was used for flood simulation and mapping. The ALOS 12.5 m Digital Elevation Model (DEM) was used to extract river geometry, and the flows generated in these river basins using RCP scenarios were used as the inflow boundary condition. Severe flooding would inundate an area of ~66%, ~86%, ~37% (under mid-21st century), and an area of ~72%, ~93%, ~59% (under late 21st century RCP 8.5 scenario) in the Chitral, Hunza, and Astore river basins, respectively. There is an urgent need to develop a robust flood mitigation plan for the frequent floods occurring in northern Pakistan.

scholarly journals Kecenderungan dan Perubahan Hujan Ekstrem Harian di Pulau Madura

2020 ◽  
Vol 18 (1) ◽  
pp. 89-96
Author(s):  
Ahmad Nur Akma Juangga Fura ◽  
Retno Utami Agung Wiyono ◽  
Indarto Indarto
Keyword(s):  
Flood Hazard ◽  
Parametric Method ◽  
Extreme Rainfall ◽  
Kendall Test ◽  
Random Processes ◽  
Rain Gauge ◽  
Rainfall Trend ◽  
Significance Level ◽  
High Level ◽  
Crossing Test

Madura subject to a high level of flood hazard. One of the main causes of flood is extreme rainfall. Global warming generates changes in the amount of extreme rainfall. This research is conducted to identify and to analyze the trends, changes, and randomness of 24-hour extreme rainfall data on Madura Island. The method used is a non-parametric method which includes the Median Crossing test, the Mann-Kendall test, and the Rank-Sum test at the significance level of α =0.05. The analysis was carried out on 31 rain gauge stations. The recording period observed is between 1991-2015. The results of the analysis show that based on the Median Crossing test, most rainfall stations have data originating from random processes. The result shows also that the maximum 24-hour extreme rainfall trend is significantly decreased in a few locations, while for the majority of other stations have no experience a significant trend.

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