Flood Risk and Impact Analysis of Varanasi City Region, India (original) (raw)
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URBAN FLOOD MANAGEMENT AND MONITORING IN VRISHABHAVATHI VALLEY
IAEME, 2019
Urban flood is mostly seen in urban areas. They may be due to heavy rainfall, adverse topographical conditions and anthropogenic factors, lead to destruction of drainage, damage to buildings, and even loss of life and property. Now in order to control such problems, systematic urban flood studies are necessary. This study is focused on the mapping and spatial analysis of urban flood vulnerability in Vrishabhavathi valley watershed, Bengaluru using Analytical Hierarchy Process (AHP), GIS and remote sensing techniques. Few causative factors for flooding considered are rainfall, slope, drainage density, land use, building density, road density, non-existing natural drainage and non-existing Lake. The thematic map of these factors was converted into raster maps. Numerical weight and ranking scores will be assigned to each element factor according to fundamental scale of AHP technique. Urban Flood Vulnerability Zone (UFVZ) map is computed using weighted overlay analysis of GIS technique and classified into five categories, viz., very low, low, moderate, high and very high flood zone classes. UFVZ map was compared with the flood prone locations exist in Bengaluru city to assess the accuracy of result. The plot of flood prone locations on flood vulnerability zone map evident that, 50% of flood prone locations found under moderate flood vulnerability zone. This result depicts the fact that, urban flood vulnerability is highly influenced by anthropogenic factors than natural factors in urban environmental study area. The predicted flood vulnerability zones are found to be in good agreement with known flood prone locations.
2015
In the past, there have been severe climatic conditions occurring in most part of the earth due to climate change. As a result of this, the intensity of rainfall has increased tremendously causing flooding in many areas and countries worldwide. Therefore, it is very important to have a thought on such a natural hazard to minimize the impact which it creates on public and environment. In order to prepare from such calamity, vulnerable areas for flood affection need to find out. In flood risk management activity demarcation of flood prone areas plays an important role. Therefore, in this research paper, efforts were made to find out the flood prone areas by using remote sensing, (DEM) digital elevation model data and GIS techniques. LISS III satellite data, Cartosat DEM have been used to generate the slope gradient of the study area. To get the different level of flood risk map, the slope gradient map has been reclassified in low risk, medium risk and high risk zone maps. It is recomm...
Flood is a major environmental problem in India as it has devastating effects on life and property. The objective of present study is to delineate and identify flood hazard and risk assessment at landscape level using Landsat satellite data from 1974-2013 in Chamoli District, Uttarakhand, India covering total geographical area of 8030 km2. The study area lies between 30-31° N latitude and 79-80° E longitude. The satellite data was ortho-rectified and the study area was extracted using district boundary. The vegetation type/land use map was prepared using on-screen visual interpretation technique. The multi-flood time series dataset was used for preparation of Digital Elevation Model. Geographical Information System was used for identification of flood prone areas which were classified with zone-wise. A flood frequency map was developed using the multi-date Landsat satellite imagery. The classified vegetation type/land use map from 1974-2013 was overlaid to find out the frequency of the flood. Flood affected areas were classified into very low, low, medium, high, very high and extremely high based on vulnerability to the potential of flood hazard. The areas were further categorized, based on the vulnerability of flood viz; extremely high (6) very high (5), high (4), medium (3), low (2) and very low (1) respectively. The study assigned the scores to each class for further determination of risk zone in various thematic layers such as slope, aspect and elevation. The incorporation of all thematic layers and flood frequency map was generated to prepare flood hazard and risk map using GIS platform. Flood frequency and flood prone areas were calculated using DEM. The vegetation type/land use map was integrated for creation of flood hazard and risk assessment. Based on this analysis the flood risk zones at different levels and intensity in the Chamoli district were prepared. This flood hazard and risk assessment maps will be useful to management and mitigate losses of lives and property from recurrent flood disasters in Chamoli District. This model can also be applied to comparable areas in Himalayas.
Flood Risk Analysis of Upper Krishna Sub-Basin using GIS
International Journal for Research in Applied Science & Engineering Technology (IJRASET), 2022
Floods are the most and repeatedly occurring destructive natural disaster due to an overflow of water submerges land which is basically dry. Generally, floods are occurring due to heavy rainfall or cloud bursting or manmade disturbance to nature, fast snowmelt, global warming or tropical cyclone or tsunami. In 2019, the Krishna River has faced very heavy rainfall and major floods which took the lives of approximately 500 people and nearly isolating 350 villages and leaving millions homeless. Here we studied the previous flood disaster at the basin of the Krishna River and processed the GIS environment using software tools. This facilitates exploring the data and methods that are mostly unexplored, and areas that have not lightened in the field of flood studies in Krishna basin. It is impossible to avoid floods and risk associated with flood, however it is possible to work on the flood reduction. Flood hazard mapping is to identify comparatively safe sites in high elevation with low risk is one of the powerful tools for this purpose. Flood hazard mapping flash flood will be beneficial for risk assessment. Management and emergency services during flood events. The objective of this paper is to generate flood hazard zonation maps of Upper Krishna sub-basin using GIS tools and satellite images. To do so, we use spatial data and SRTM DEMs with accuracy assessment is achieved by using check points, obtained by GPS observations. Runoff, surface slope, drainage density, distance to main channel and land use were considered causative factors. All used data are processed and integrated in an ArcMap and QGIS to prepare a final flood hazard map for Upper Krishna sub-basin. The areas in high risk flood zones are obtained by overlaying the flood hazard index map with the zone boundaries layer..
Sustainability
Urban floods are very destructive and have significant socioeconomic repercussions in regions with a common flooding prevalence. Various researchers have laid down numerous approaches for analyzing the evolution of floods and their consequences. One primary goal of such approaches is to identify the areas vulnerable to floods for risk reduction and management purposes. The present paper proposes an integrated remote sensing, geographic information system (GIS), and field survey-based approach for identifying and predicting urban flood-prone areas. The work is unique in theory since the methodology proposed finds application in urban areas wherein the cause of flooding, in addition to heavy rainfall, is also the inefficient urban drainage system. The work has been carried out in Delhi’s Yamuna River National Capital Territory (NCT) area, considered one of India’s most frequently flooded urban centers, to analyze the causes of its flooding and supplement the existing forecasting model...
ASSESSMENT OF FLOOD USING GEOSPATIAL TECHNIQUE FOR INDUS RIVER REACH: CHASHMA -TAUNSA
Floods are the most critical among all the natural calamities in world causing vast damages to life and property. It is thus essential to address this natural calamity by developing integrated approach for flood modelling and mapping for future prevention of flood and to decrease the effect it causes on property and people. In this study Indus River reach Chashma- was selected for flood modelling and mapping for normal flood of 2006 and exceptionally high flood of 2010 due to which lot of damages occurred to life and property. Flood hydraulic modelling and floodplain mapping was integrated to perform flood routing for the computation of peak flow attenuation, assessment of lag time between inflow and out flow and to perform mapping for the estimation of flood zone depth and flooded area of reach. To perform hydraulic modelling and floodplain mapping HEC-RAS, ARC-GIS and its extension Hec-GeoRAS were used as tools. HEC-RAS model input cross-sections data were collected from physical survey and extracted from DEM SRTM 90 m by using Hec-GeoRAS. HEC-RAS model accuracy has been determined by numerical prediction at upstream of Taunsa barrage of Indus River against the observed data. The statistical comparison by coefficient of determination (R 2 ) (0.95 & 0.90) and Nash and Sutcliffe coefficient (0.93 & 0.86) demonstrated that the numerical simulation of model has a good agreement with observed flow at upstream of Taunsa barrage. Model stability has been observed during simulation of the flood discharge in study reach. Comparison of lag times for observed and computed flood peaks 2010 and 2006 has been carried out, which show almost good agreement (3 days and 6 hours, and 2 days for 2006 and 2010 flood respectively are well matched with the observed values 3.5 days and 2 days and 6 hours for 2006 and 2010 flood respectively). Results of HEC-RAS model were exported in ARC-GIS to perform flood mapping. Flood maps of the whole study area were finally prepared for 2010 flood. Integrated modeling approach used in the study performs well to assess areas vulnerable to flood with estimation of depth and area of flooded extent; calculated as 8.1 m and 1900 km 2 respectively for 2010 flood.
In recent years humans have endured increasing number of natural disasters, of which flood is the greatest and most common throughout the world. Flood plains are thickly populated because of their economic significance. The present study area, Vamanapuram River Basin in Kerala State, India presents a challenge in terms of repeated flash flood hazard in some parts. The present study aims to prepare Flood hazard zone map of Vamanapuram River Basin based on Multi Criteria Evaluation method using Remote Sensing, GIS and GPS tools. Present study is limited to factors such as rainfall distribution, drainage density, land use/land cover, soil, size of micro watershed, slope, and roads per micro watershed, to prepare the Flood hazard zone map. The thematic maps of these factors are prepared using ArcGIS and ERDAS IMAGINE tools. By assigning ranks and weights to these thematic maps, the weightage maps are created. In this study Weighted Overlay Analysis method is adopted to prepare the Flood hazard zone map. The hazard map thus prepared will show the total areas subjected to the hazards, as very low, low, moderate, high, and very high hazard zones. By preparing the hazard zone map, we can propose measures to reduce the risk of these hazards in Vamanapuram River Basin.
Urban Flood Hazard Zonation in Bengaluru Urban District, India
Journal of Landscape Ecology, 2024
Flooding in urban areas is increasingly becoming a global challenge, driven by extreme rainfall events and the vulnerability or resilience of affected regions. This urban flood disaster not only threatens societal security but also hampers economic development in cities. Satellite remote sensing technology has played a crucial role in all aspects of flood disaster management, including preparedness, prevention, and relief efforts. Space systems, with their advantageous perspective, have proven their ability to provide essential information and services for effective flood management. This study focuses on creating flood hazard maps for Bengaluru's urban district using an Analytical Hierarchy Process (AHP)-based Multi-Criterion Decision Analysis (MCDA) and Geographic Information System (GIS) techniques. Factors such as rainfall, drainage networks, land use, groundwater levels, terrain elevation, slope, and soil type are considered. The AHP method assigns weights and ranks to each factor, and a weighted linear combination approach is used to merge basic maps into the final flood vulnerability map.
A Geospatial Study of Urban Floods in Hyderabad City
International Journal of Science and Research (IJSR), 2022
India is one of the world's regions that is most vulnerable to natural disasters, which results in yearly in Hyderabad also losses of property, infrastructure, and human lives. Monitoring and evaluating the floods and other disasters can be done from a unique vantage point by using air and space-based observations of the globe. Geospatial technology has significantly enhanced flood research, particularly in the first three phases of floods. Specifically, there are three phases: a) preparation for floods; b) monitoring for floods; and c) recovery from floods (damage assessment and mitigation phase). Agriculture, socioeconomic, communication, population, and infrastructure data are all included in the GIS data set that was developed during the preparation phase. In the event of a serious flood crisis in Hyderabad, this can be utilised in conjunction with the flooding data to adopt an evacuation strategy, rehabilitation planning, and damage assessment.