The Sundarban, covering about one million ha in the delta of the rivers Ganga, Brahmaputra and Meghna is shared between Bangladesh (~60%) and India (~40%), and is the world’s largest coastal wetland. The area experiences a subtropical monsoonal climate with an annual rainfall of 1,600–1,800 mm and severe cyclonic storms. Enormous amounts of sediments carried by the rivers contribute to its expansion and dynamics. Salinity gradients change over a wide range of spatial and temporal scales. The biodiversity includes about 350 species of vascular plants, 250 fishes and 300 birds, besides numerous species of phytoplankton, fungi, bacteria, zooplankton, benthic invertebrates, molluscs, reptiles, amphibians and mammals. Species composition and community structure vary east to west, and along the hydrological and salinity gradients. Sundarban is the habitat of many rare and endangered animals (Batagur baska, Pelochelys bibroni, Chelonia mydas), especially the Royal Bengal tiger (Panthera tigris). Javan rhino, wild buffalo, hog deer, and barking deer are now extinct from the area. Large areas of the Sundarban mangroves have been converted into paddy fields over the past two centuries, and more recently into shrimp farms. The Sundarban has been extensively exploited for timber, fish, prawns and fodder. The regulation of river flows by a series of dams, barrages and embankments for diverting water upstream for various human needs and for flood control has caused large reduction in freshwater inflow and seriously affected the biodiversity because of an increase in salinity and changes in sedimentation. Heritiera fomes (locally called Sundari, from which Sundarban derives its name), Nypa fruticans and Phoenix paludosa are declining rapidly. During the past three decades, large parts of the remaining Sundarban have been protected for wildlife, particularly tiger, through the creation of several sanctuaries and a biosphere reserve. Parts of the Sundarban in both India and Bangladesh have been declared World Heritage sites. However, its biodiversity continues to be threatened by a growing human population that not only places pressure on its biological resources, but also impacts on the freshwater inflows from upstream areas. Oil exploration in coastal areas is also emerging as a new threat. Further threats arise from global climate change, especially sea level rise. The future of the Sundarban will depend upon the management of freshwater resources as much as on the conservation of its biological resources.

http://portal.nceas.ucsb.edu/working_group/valuation-of-coastal-habitats/relevant-papers/various-mangroves-related-papers/Gopal%20and%20Chauhan%2C%202006.pdf/attachment_download/file

Biodiversity and its conservation in the Sundarban Mangrove Ecosystem

Magnetars are the strongest magnets in the present universe and the combination of extreme magnetic field, gravity and density makes them unique laboratories to probe current physical theories (from quantum electrodynamics to general relativity) in the strong field limit. Magnetars are observed as peculiar, burst-active x-ray pulsars, the anomalous x-ray pulsars (AXPs) and the soft gamma repeaters (SGRs); the latter emitted also three 'giant flares', extremely powerful events during which luminosities can reach up to 10(47) erg s(-1) for about one second. The last five years have witnessed an explosion in magnetar research which has led, among other things, to the discovery of transient, or 'outbursting', and 'low-field' magnetars. Substantial progress has been made also on the theoretical side. Quite detailed models for explaining the magnetars' persistent x-ray emission, the properties of the bursts, the flux evolution in transient sources have been developed and confronted with observations. New insight on neutron star asteroseismology has been gained through improved models of magnetar oscillations. The long-debated issue of magnetic field decay in neutron stars has been addressed, and its importance recognized in relation to the evolution of magnetars and to the links among magnetars and other families of isolated neutron stars. The aim of this paper is to present a comprehensive overview in which the observational results are discussed in the light of the most up-to-date theoretical models and their implications. This addresses not only the particular case of magnetar sources, but the more fundamental issue of how physics in strong magnetic fields can be constrained by the observations of these unique sources.

http://iopscience.iop.org/article/10.1088/0034-4885/78/11/116901/pdf

Magnetars: the physics behind observations. A review.

Magnetars are the strongest magnets in the present universe and the combination of extreme magnetic field, gravity and density makes them unique laboratories to probe current physical theories (from quantum electrodynamics to general relativity) in the strong field limit. Magnetars are observed as peculiar, burst--active X-ray pulsars, the Anomalous X-ray Pulsars (AXPs) and the Soft Gamma Repeaters (SGRs); the latter emitted also three "giant flares," extremely powerful events during which luminosities can reach up to 10^47 erg/s for about one second. The last five years have witnessed an explosion in magnetar research which has led, among other things, to the discovery of transient, or "outbursting," and "low-field" magnetars. Substantial progress has been made also on the theoretical side. Quite detailed models for explaining the magnetars' persistent X-ray emission, the properties of the bursts, the flux evolution in transient sources have been developed and confronted with observations. New insight on neutron star asteroseismology has been gained through improved models of magnetar oscillations. The long-debated issue of magnetic field decay in neutron stars has been addressed, and its importance recognized in relation to the evolution of magnetars and to the links among magnetars and other families of isolated neutron stars. The aim of this paper is to present a comprehensive overview in which the observational results are discussed in the light of the most up-to-date theoretical models and their implications. This addresses not only the particular case of magnetar sources, but the more fundamental issue of how physics in strong magnetic fields can be constrained by the observations of these unique sources.

Magnetars: the physics behind observations

The sea level could increase 02 or 22 by 2100 hinging on the effects of carbon dioxide and chlorofluorocarbons on atmospheric temperature changes parallel heat transfer to and thermal expansion of the ocean more precipitation and melting of polar ice Local sea level increases also depend on subsidence Normally deposition of sediment equalizes delta subsidence Yet many activities change this balance including channeling diverting or damming rivers; destruction of mangrove forests; and removal of groundwater or hydrocarbons Large increases in local sea level are a problem especially for low lying deltas with a large human population 80% of Bangladesh comprises the Bengal Delta Annual floods can cover as much as 35% of the entire country India has diverted flow from the Ganges causing rising salinity in coastal streams in Bangladesh Considerable drilling of shallow and deep wells has resulted in subsidence of twice the normal rate Destruction of mangrove forests increases coastal erosion in Bangladesh In Egypt almost all the productive land and most of the population are located in the Nile Delta The coast has an almost endless band of 1-5 m dunes which could protect Egypt against a sea level rise but the Aswan Low and High dams have prevented the deposition of sediment in the Delta leading to coastal erosion They have also ceased the freshwater influx to the delta causing increased salinization of soils This in turn increases the demand for drilling shallow and deep wells and the increased removal of groundwater hastens subsidence By 2100 local sea level rises of these 2 deltas may be as high as 33 45 m This could result in the loss of 26% of habitable land in Egypt and 34% in Bangladesh Rising sea levels would worsen environmental and economic effects Future coastal and fluvial planning for all areas with low lying deltas and large rivers should consider these scenarios

https://www.jstor.org/stable/info/4313605

Environmental and economic implications of rising sea level and subsiding deltas: the Nile and Bengal examples.

The storm surge problem in the bay of Bengal

Estimates of the surge generated by a model storm impinging on three coastal areas of north Bay of Bengal are presented. A linear shallow-water long-wave model was used to evaluate the surge. Surge amplitudes were computed for different values of storm intensity and speed. The effect of the astronomical tide was estimated by specifying initial boundary conditions on the open boundary of the computational grid. For a devastating storm, which struck Bangladesh (formerly East Pakistan) on 12/13 November 1970, we show that superposition of the surge on the tide leads to an overestimate of sea level elevation at the time of landfall.

Storm surges in the Bay of Bengal

Hypernuclear matter in strong magnetic field

We describe the microphysics, phenomenology, and astrophysical implication of a $B$-field induced unpairing effect that may occur in magnetars, if the local $B$ field in the core of a magnetar exceeds a critical value ${H}_{c2}$. Using the Ginzburg-Landau theory of superconductivity, we derive the ${H}_{c2}$ field for proton condensate taking into the correction $(\ensuremath{\le}30%)$ which arises from its coupling to the background neutron condensate. The density dependence of pairing of proton condensate implies that ${H}_{c2}$ is maximal at the crust-core interface and decreases towards the center of the star. As a consequence, magnetar cores with homogenous constant fields will be partially superconducting for ``medium-field'' magnetars $({10}^{15}\ensuremath{\le}B\ensuremath{\le}5\ifmmode\times\else\texttimes\fi{}{10}^{16}\text{G})$ whereas ``strong-field'' magnetars $(Bg5\ifmmode\times\else\texttimes\fi{}{10}^{16}\text{G})$ will be void of superconductivity. The neutrino emissivity of a magnetar's core changes in a twofold manner: (i) the $B$-field assisted direct Urca process is enhanced by orders of magnitude, because of the unpairing effect in regions where $B\ensuremath{\ge}{H}_{c2}$; (ii) the Cooper-pair breaking processes on protons vanish in these regions and the overall emissivity by the pair-breaking processes is reduced by a factor of only a few.

Magnetar superconductivity versus magnetism: Neutrino cooling processes

Ganga River basin, which was comparatively free from anthropocentric activities until the 1940s, became a disposal site for agricultural, industrial and sewerage wastes after independence of India in 1947. Discharge of wastes generated due to developmental activities including irrigation projects, river course modifications and demographic explosion in the basin, have ecologically impaired the river system, so that water quality is degraded, and fish yield as well as biodiversity has decreased. Amongst these, irrigation projects and flood control measures have almost destroyed flood plains, sloughs, inundation zones and oxbow lakes, all of which are the breeding and nursing grounds of the prized Indian major carp. This led to decline of the major carp population, while less economic fishes (minor carps and small catfishes) are increasing in relative abundance. The hydraulic structures have destroyed the anadromous fisheries ( Tenualosa ilisha, Pangasius pangasius ) of the riverine stretch of the Ganga. Ho...

Impact of environmental aberrations on fisheries of the Ganga (Ganges) River

model. The confinement is modeled by means of the Richardson potential for quark-quark interaction modified suitably to account for a strong magnetic field. We compare our results for the equation of state and magnetization of matter to those derived within the MIT bag model. The differences between these models arise mainly due to the momentum dependence of the strong interaction between quarks in the Richardson model. Specifically, we find that the magnetization of strange quark matter in this model �

Monika Sinha

Papers

Storm surges in the Bay of Bengal

Hypernuclear matter in strong magnetic field

Magnetar superconductivity versus magnetism: Neutrino cooling processes

Impact of environmental aberrations on fisheries of the Ganga (Ganges) River

Strange quark matter in strong magnetic fields within a confining model