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Flood-Prone Ghatal Region, India: A Study on Post-‘Phailin’ Inundations of 2013
Abstract
Located at the base of the Chhota Nagpur Plateau’s fringe fan system, the Ghatal region in the Indian state of West Bengal is highly vulnerable to recurring floods. The region typically becomes flooded 3–5 times in a year; usually floodwaters remain stagnant for a long period of time owing to the typical basin-shaped topography of the area. A complex drainage system has evolved due to, on the one hand, the low gradient of the Shilabati–Dwarkeshwar–Rupnarayan Rivers and their numerous tributaries and distributaries and, on the other hand, to man-made irrigation channels. These rivers struggle to carry surplus run-off water during high discharge events. In addition, these rivers receive significant run-off from the upstream reservoirs of the Damodar Valley Corporation (DVC) and Kangsabati Project (KP). These factors combine into a disastrous flood scenario. In October 2013, due to the cyclone ‘Phailin’, both the Chhota Nagpur Plateau region of Jharkhand and the western part of West Bengal received extremely high levels of rainfall within a short amount of time, which caused much flooding in the Ghatal region. Almost 75% of the Ghatal Community Development (CD) Block was inundated; some areas remained flooded for a month thereafter. This study attempts to figure out the characteristics of the post-Phailin flood crisis through a field survey combined with satellite images and a digital elevation model (DEM) analysis, as well as secondary information acquired from various sources. The physiographic setting and drainage characteristics are analysed with the help of said DEM as well as multi-dated satellite images, various hydro-geomorphic techniques, spatial overlay and ground truth verification (GTV). Information on geology, rainfall, flood history, tidal character, demography, etc. was obtained from administrative departments and from various reports and literatures. Oral interviews with administrative personnel and local citizens helped understand the floodwater flow pattern—most especially the role of circuit embankments of Ghatal erected in the nineteenth century under British Raj in obstructing the natural drainage of this region. The present drainage system does not follow the natural slopes—ill-thought-out construction of embankments led to the formation of potential flood valleys cutting through the Shilabati and Dwarkeshwar courses a number of times. This results in breaches within the embankments and recurring floods. The region’s low gradient and the routine reversal of river flows due to upstream tidal flows are responsible for prolonged inundations. The 1980s Ghatal Master Plan (GMP) and the 2009–2011 WAPCOS Project prioritized the construction of a continuous, high-level embankment on the Shilabati’s left bank and the artificial resuscitation of the river’s lower areas. However, the implementation of these plans can lead to a variety of unintended consequences.
In the current study, subsurface characteristics within the complex formation of the Shilabati basin system of West Bengal, India, extending over an area of 3888 km², have been estimated using a cost-effective piezometer and MIKE FEFLOW package based on a steady-state numerical model. Pore size and fine particle content of streambeds are affected by two opposing flow contraptions. Such opposite flow conditions are likely to affect the hydraulic conductivity of the streambed. However, analogies of the hydraulic conductivity (Kh) of streambeds for losing and gaining streams have not been well documented in the recent past. The Kh value from the piezometer has been highest at the Dakshin Pairachali site (6.765 m/day), with the stream gaining water from the discharge of the local aquifer. Analysis of the stream-aquifer interaction using the FEFLOW model has allowed us to understand the groundwater water head of the basin ranging from 160.33 to 0.32 m.a.s.l (meters above sea level). The present study also constitutes the first attempt for the identification of suitable sites for the implementation of managed aquifer recharge (MAR) technology in West Bengal, India, to manage extreme drought events. The suitable sites have been identified by means of three fuzzy multi-criteria decision analysis based on nine criteria: river discharge, moisture content, porosity, drainage type, rainfall, land use type, geology, aquifer material, and hydraulic conductivity. To design a radial collector well and infiltration gallery for the selected site in an anisotropic, homogeneous, unconfined, and semi-infinite aquifer near a fully penetrating stream, a pumping test has been conducted to optimize a safe yield of 12.096 MLD (megaliters per day).
A few years back, when travelling flooded Bengal, a graduate student from Ahmed
Draia University said, ‘You have too many water resources to manage, but we die
from dehydration’. He uttered the serious truth of the Earth’s extreme contrast of
climate. Rather, extreme contrast of all – the soil, the water, the air, the life and the
living. In India, better all over the world, the threat of water scarcity is increasing day
by day. It is reported that even the Bengal basin will come under the threat of
permanent drought in near future. The lowering of groundwater level in the Bengal
basin is ringing the alarm. Discharges of rivers are diminishing rapidly. Some rivers
have dried out and got lost. Many lakes and swamps have ceased to exist.
Yet our fellows get killed under flood water! Our cattle and poultry get washed
away. Each year, either here or there, floods toll our lands, our properties. We, from
the Ganga-Brahmaputra-Meghna delta, suffer the pains of floods. It goes beyond our
capacity for utilization and management. The flood erases all differences in terrain.
Even barriers of international border crossings disappear under flood water and make
the landscape uniform. People of different nations feel the pain and suffering of
floods the same way. Regarding floods, India and Bangladesh have fellow feelings.
Moreover, during the Covid-19 situation, we became accustomed to online communication to come closer.
In 2020, when the Covid-19 pandemic locked down the entire world, Dr Aznarul
Islam took the initiative to introduce ourselves to each other, and eventually, we
came closer to thinking on a single point with multi-dimensions – the flood. We felt
the urge to work and invited articles on ‘Floods in the Ganga-Brahmaputra-Meghna
Delta’ and did pile huge responses from worldwide contributors, which offered us
the opportunity to be selective. We are very much thankful to our authors who
contributed to this volume. Their thought-provoking contributions made this volume
knowledgeable. We are also equally thankful to our compadre authors, whose
articles do not appear as chapters in this volume but who made us feel blessed
with their articles rich in noesis.
We are grateful to Dr Guido Zosimo-Landolfo, Editorial Director/Asset Manager
of Springer Nature Switzerland AG, for signing the agreement on this project and
providing the opportunity of using their prestigious pages for manuscripts of our
eminent authors.
We hope, the outcomes of this volume will flood the thoughts of scholars,
faculties, planners and stakeholders returning us the apt worth.
Climate change has increased hazardous events associated with tropical cyclones, which ultimately increased the intensity of other extreme events such as flooding and associated impacts. This event has increased the vulnerability of low-lying areas, deltas, coasts, and islands in many parts of the world including Indian subcontinent. Floods and water-related disasters and their associated problems are the most common natural calamity in most parts of West Bengal. The flood is frequently occurring in every year in many low-lying areas of West Bengal. The existing study has been completed with the use of geospatial technology both remote sensing (RS) and GIS environment in Pratappur village, Ghatal Block, Paschim Medinipur district. This study aims toward the shifting nature of river course and assessment of flood vulnerability zones in the study area. The position of Silaboti River has affected more this area. The depth of riverbed is low to hold huge discharge, especially during monsoon. The area is characterized by low-lying land. People inhabited in this area are habituated and adopted with the occurrence of two or three times flood situation in a year. A devastating flood happened in 2017 due to breaching of Chetua circuit embankment at Pratappur, located at the left bank of Silaboti River. This event inundated 93.27 km2 of area and stayed for 45 days.KeywordsShifting of river course
Flood vulnerability
RS& GIS techniqueSilaboti riverGhatal block
Floods, being the most common natural disaster, affect millions of people worldwide. Out of 3290 lakh hectare (3,290,000 km2) land area in India, 40 million hectares have been declared as flood prone, with an annual average of 75 lakh hectares being affected, either directly or indirectly. West Bengal is considered as one of the most flood-prone states in India, with its southern portion being severely affected by floods annually. Although natural factors are probably the usual causes of floods, the Silabati (also called Silai) River basin, near its mouth in the vicinity of Ghatal town of Paschim Medinipur district, experiences annual flooding partly due to its regional setting within the subdued Bengal fan, while much of the inundation here occurs due to direct anthropogenic interventions into the channel and the floodplain. The various natural and anthropogenic causes of flooding in the region have been explained in this study with a special emphasis on the embankment circuits of the area that make the river flow constrained, thereby causing siltation and rising of the river bed with resultant flooding. An analysis of the extent, recurrence and duration of flooding in the region has also been done to highlight the severity of the event and the annual suffering of the resident communities in the region. The formulation of the Ghatal Master Plan in the region has not been much of a success, with non-structural mitigation measures being a viable means to reduce floods in the region.
Groundwater crisis is playing a serious concern in the Shilabati river basin located in a tropical plateau fringe region of the south eastern part of West Bengal, India. The river rises from the geological structure of Chotonagpur gneissic complex where groundwater recharge is very poor and is affected by yearly drought scenarios with a prolonged shortage of water supply. The present research is to address this issue through a number of statistical techniques and multicriteria decision-making approaches (MCDM). To accomplish the research objectives, morphometric attributes of 9 sub-watersheds of Shilabati river basin having a total area of 3881 km2 have been estimated. Principle component analysis (PCA) has been used to group these attributes into three components and K-means clustering categorised the sub-watershed into 3 cluster based on mor-phometric asymmetry. Basin prioritisation based on recharge and infiltration capacity using three MCDM techniques like Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), Complex Proportional Assessment (COPRAS) and VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) ranked the sub-watersheds where TOPSIS has been selected as the best model using spearman rank correlation coefficient test. According to the TOPSIS model, Donai sub-watershed ranked 1st and proved greater amplitude in recharging its aquifer where the yield capacity of wells ranges from 200 to 400 LPM (litre per minute). The sub-watersheds like Betal and Joypanda need sustainable management at the prior level as validated by groundwater yield data where the yield capacity of wells ranges from 10 to 100 LPM. The methodol-ogy is proficient enough for the decision-makers to execute groundwater management and planning strategies substantially.
In September 2000 at the end of a good monsoon and during a tropical cyclonic storm, Bengal suffered a particularly severe flood in which more than 1,500 people died. In West Bengal more than 20 million people and in Bangladesh more than 3 million lost their homes and virtually all of their possessions. This paper explores different experiences of the disaster, and many differing explanations of its causes, both physical and social. It proposes the idea that the specific form of development that has taken place in Bengal since the mid nineteenth century, the ‘standard’ road–rail and urban–industrial model, has been transplanted into an inappropriate geographical setting. The result is that the urban sector has externalised its costs onto the rural poor. In this context it is suggested that the new ‘open policy’ on floods, also advocated elsewhere in the world, be seriously considered as more appropriate and sustainable for Bengal.
Detailed photogeomorphological studies were carried out in West Bengal Basin to understand the present day Bengal Delta, its morphology and processes responsible for its development. The Quaternary Geology of the area is constituted of deposit of lateritic uplands in the west followed in the east by those of paleo/sub deltaic plains, younger fluviodeltaic plains and the recent tidal flat and beach ridge complexes. The lateritic uplands exhibit dark photo tone, sparse drainage, hummocky and pitted appearance. The paleo deltaic plain exhibits dark photo tone with distributary and radiating river channels (resembling alluvial fans), with occurrence of clean yellowish brown, medium to coarse grain sands in the subsurface. -from Authors
Rivers are the important primary resource of landed community for their primary sustenance. Losses of navigability, gradient fall within a short distance, deltaic formations in lower reaches, anthropogenic actions or manipulations such as construction of embankments and guard walls, silt depositions or encroachment of river beds, monsoon induced changes, etc., can cause a river to die. As per the current status of West Bengal (Eastern part of India) and Jharkhand rivers, the effect of the creation of reservoirs, industrial extractions, and climate change can be observed easily. Damodar and Rupnarayan river systems are two major river networks of eastern India which are one of the major sources of water for irrigation, agriculture, and industrial purposes of the people living in the river banks. The present note tries to give an overview of the current trends, geomorphological characteristics, and economical resources of the two rivers which can give an idea of the impact of vulnerabilities on the natural water resources of the two catchments.
Many developing countries are very vulnerable to flood risk since they are located in climatic zones characterised by extreme precipitation events, such as cyclones and heavy monsoon rainfall. Adequate flood mitigation requires a routing mechanism that can predict the dynamics of flood waves as they travel from source to flood-prone areas, and thus allow for early warning and adequate flood defences. A number of cutting edge hydrodynamic models have been developed in industrialised countries that can predict the advance of flood waves efficiently. These models are not readily applicable to flood prediction in developing countries in Asia, Africa and Latin America, however, due to lack of data, particularly terrain and hydrological data. This paper explores the adaptations and adjustments that are essential to employ hydrodynamic models like LISFLOOD-FP to route very high-magnitude floods by utilising freely available Shuttle Radar Topographic Mission digital elevation model, available topographical maps and sparse network of river gauging stations. A 110 km reach of the lower Damodar River in eastern India was taken as the study area since it suffers from chronic floods caused by water release from upstream dams during intense monsoon storm events. The uncertainty in model outputs, which is likely to increase with coarse data inputs, was quantified in a generalised likelihood uncertainty estimation framework to demonstrate the level of confidence that one can have on such flood routing approaches. Validation results with an extreme flood event of 2009 reveal an encouraging index of agreement of 0.77 with observed records, while most of the observed time series records of a 2007 major flood were found to be within 95 % upper and lower uncertainty bounds of the modelled outcomes.
I. General Considerations .
1. Introduction —It may seem presumptuous in one who is neither a geologist nor has any pretension to geological knowledge to venture to address this Society on a subject so nearly akin to their special science. My excuse must be that, having resided for five years on the banks of one of the most active of the Bengal rivers, I have had opportunities which are not vouchsafed to every one of observing their phenomena, and have been a witness of the changes I am about to describe. I may also, perhaps, be allowed to state that, when I first became aware of the disturbance that was taking place around me, I set myself carefully to measure and observe what was passing; and , in 1835, made a sketch-survey of the lower Ganges and Brahmapootra, from Jaffiergunge to the sea. This was published by Mr. Tassin a few years afterwards, and is, so far as I know, the only survey that was made—certainly the only one published—between that made by Major Rennell and the survey now in progress, but which has not yet been given to the world. I may also mention, in extenuation, that I have waited for more than a quarter of a century in order that some one more worthy might undertake the task; but, as no one has come forward, I may perhaps be now excused for venturing upon it.
In order, however, to obviate the reproach of presumption, my intention is to confined myself
The movement of Antarctica with respect to South America has a number of implications for paleocirculation as well as for the reconstructions of Gondwanaland. Recent papers on the Southwest Indian Ridge have published new or revised poles of opening for Africa and Antarctica which can be combined with the poles of opening between South America and Africa to give resultant motions between South America and Antarctica.The first indication of a complete closure between South America and the Antarctic Peninsula is at anomaly 28 time (64 Ma) as the two continents are now configured. Between anomaly 28 time (64 Ma) and anomaly M0 time (119 Ma) the amount of closure does not change greatly, and the small computed overlap can be explained by minor uncertainties in the rotation poles used for the reconstructions or some slight extension between East and West Antarctica. By 135 Ma some rotation or translation of the Antarctic Peninsula with respect to East Antarctica must be postulated in addition to any presumed extension between East and West Antarctica in order to avoid an overlap of South America with the Antarctic Peninsula.Having determined what we feel to be a viable reconstruction of Western Gondwanaland and holding South America fixed, we rotated Africa and Antarctica, with respect to South America, for eight different times during the past. Africa moved away from South America in a more or less consistent manner throughout the time period, closure to present, while Antarctica moved away from Africa in a consistent manner only between 160 Ma and 64 Ma. At 64 Ma its motion changed abruptly: it slowed its north-south motion with respect to Africa and began slow east-west extension with respect to South America. This change supports the hypothesis that a major reorganization of the triple junction between Africa, Antarctica and South America occurred between 60 and 65 Ma. The triple junction changed from ridge-ridge-ridge to ridge-fault-fault at the time of the major westward jump of the Mid-Atlantic Ridge just south of the Falkland-Agulhas Fracture Zone.The Mesozoic opening of the Somali Basin moved Madagascar from its presumed original position with Africa in Gondwanaland. The closure of Sri Lanka with India produces a unique fit for India and Sri Lanka with respect to Africa, Madagascar and Antarctica. This fit juxtaposes geological localities in Southeast India against similar localities in Enderhy Land. East Antarctica. The late Jurassic opening in the Somali Basin is tied to opening of the same age in the Mozambique Basin. Since this late Jurassic movement represents the initial break-up of Gondwanaland, it is assumed that similar movement must have occurred in what is now the western Weddell Sea and may also explain the opening evidenced by the Rocas Verdes region of southern South America.
Extension of continental crust by up to 360 km on a north-northeast azimuth in the Great Australian Bight occurred prior to the Middle Cretaceous (96 Ma) onset of seafloor spreading between Australia and Antarctica. This large amount of continental extension is constrained to the Late Jurassic (≈ 160 Ma)-Middle Cretaceous interval, about a pole estimated to lie about 40° southeastward of southeastern Australia. Using bathymetric data combined with seismic and magnetic determinations of the continent-ocean boundaries off Australia, India and Antarctica, we determine a revised fit of East Gondwanaland prior to continental extension, and at various stages thereafter. In the first stage from 160 to 132.5 Ma (≈ M11), India-Australia rotated from Antarctica with continental crustal extension between Australia and Antarctica and largely transform motion between the Coromandel Coast margin of India and the Kron Prins Olav Kyst margin of Antarctica. In the second stage, from 132.5 to 96 Ma, India rotated northwestward away from Australia-Antarctica, producing M10 and younger magnetic anomalies along the western margin of Australia. Continental extension was greatest between Australia and Antarctica during this stage.