Tropical rain forest mapping and community analysis of South Andaman Islands (India)

Present study deals with the vegetation type mapping, structure and composition analysis of the tropical forests, spread over 1,294 km² area in South Andaman Islands. Seventeen vegetation classes spreading over 89.92% forested area of the islands were mapped with the overall accuracy of 88.89%. Evergreen, semi-evergreen and mangrove forests were reasonably well distributed forests, while moist deciduous and littoral evergreen were narrowly restricted. The stocking was quite variable across the forest types. 60.04% of forested area was under medium to high canopy density. Secondary and degraded forest types were mapped. Information on floristic composition, structure and diversity of various forest types were obtained from 84 field sample plots. An inventory of 423 species of plants from 101 families included 155 trees, 84 shrubs, 150 herbs and 84 climbers. Tree density and mean basal area ranged from 517 to 900 stems ha⁻¹ and 36.15 to 53.58 m² ha⁻¹ respectively. Evergreen forests accounted for highest diversity followed almost equally by semi-evergreen and moist deciduous forests.     

Application of landscape ecology and remote sensing for assessment,monitoring and conservation of biodiversity

Landscape ecology, inter alia, addresses the question as to how altered landscape patterns affect the distribution, persistence, and abundance of a species. Landscape ecology plays an important role in integrating the different scales of biodiversity from habitat patch to biome level. Satellite remote sensing technology with multi-sensor capabilities offers multi-scale information on landscape composition and configuration. Advances in geospatial analytical tools and spatial statistics have improved the capability to quantify spatial heterogeneity. Globally, landscape level characterization of biodiversity has become an important discipline of science. Considering the vast extent, heterogeneity, and ecological and economic importance of forest landscapes, significant efforts have been made in India during the past decade to strengthen landscape level biodiversity characterization. The generic frame work of studies comprises preparation of national databases providing information on composition and configuration of different landscapes using multi-scale remote sensing techniques, understanding the landscape patterns using geospatial models to elicit disturbance and diversity patterns and application of this information for bioprospecting and conservation purposes. Studies on hierarchical linkage of multi-scale information to study the processes of change, landscape function, dynamics of habitat fragmentation, invasion, development of network of conservation areas based on the understanding of multi-species responses to landscape mosaics, macro-ecological studies to understand environment and species richness, habitat and species transitions and losses, landscape level solutions to adaptation and mitigation strategies to climate change are a few of the future challenges. The paper presents the current experiences and, analyses in conjunction with international scenario and identifies future challenges of Indian landscape level biodiversity studies.     

ANALYSIS OF ROCKBOLT REINFORCEMENT USING BEAM-COLUMN THEORY

A simple analytical procedure that applies classical beam-column theory for evaluating passive rockbolt roof reinforcement is presented in this paper. The analytical model is derived from first principles and is capable of modelling any number of reinforcing bolts. Each rockbolt is modelled as a linear spring and the model allows for non-uniform bolt spacing. In this study the rock beam is assumed to be isotropic and linearly elastic for the sake of simplicity. However, the analytical model can be extended to include anisotropic rockmass as well as inelastic material behaviour. The solution to the coupled set of governing equations is obtained by using a simple numerical solution procedure. The results from the analytical model indicate that the critical buckling load of a rock beam is strongly influenced by the ambient rock modulus. For salt-rock excavations the rock modulus typically declines with time due to various phenomena, and a diminished modulus could seriously compromise roof stability. The other main conclusion of this study is that rockbolts loose their effectiveness in restraining a roof beam once its critical buckling load is approached. In such a situation, increasing bolt stiffness does not improve its reinforcing action on a roof beam but it enhances the possibility of bolt failure due to anchor pull-out. © 1997 by John Wiley & Sons, Ltd. Int. J. Numer. Anal. Meth. Geomech., vol. 21, 241–253 (1997)     

Time-averaged flow structure in the central region of a stream confluence: a discussion

This paper is a discussion of Rhoads and Kenworthy (1998) ‘Time-averaged flow structure in the central region of a stream confluence’ Earth Surface Processes and Landforms, 23 , 171–191, that focuses upon the methods used to identify secondary circulation in river channel confluences. It argues that the Rozovskii method that Rhoads and Kenworthy use to rotate their field data to allow identification of secondary circulation cells is flawed, and can result in misleading conclusions about the nature of flow processes in confluences. It recommends that there is a re-emphasis upon helical as opposed to secondary circulation, and that recent developments in both field monitoring and numerical modelling may help significantly in this respect. Copyright © 1999 John Wiley & Sons, Ltd.     

Risk of Fluoride-Rich Groundwater on Human Health: Remediation Through Managed Aquifer Recharge in a Hard Rock Terrain,South India

The main objective of the present research was to examine the risk of fluoride-rich groundwater in the Shanmuganadhi River basin, south India on human health. The non-carcinogenic risks were estimated into two classes: (1) risks associated with oral intake of water and (2) risks associated with dermal contact. Hazard Quotient for oral intake and dermal contact was separately calculated for adult men, adult women and children from the geochemical results of 61 representative samples collected from the wells constructed in hard rock aquifers during the post- (January-2018) and pre-monsoon (May-2018) seasons. The collected samples were analyzed immediately after the field work for all the major ions and fluoride. Finally, total hazard index was calculated for adults (men and women) and children to evaluate the risk. It directed that 41%, 49% and 74% of post-monsoon samples and 30%, 43% and 62% of pre-monsoon samples possessed a non-carcinogenic risk for men, women and children, respectively. Because the basin falls in the drought-prone region, the water supply for drinking and cultivation are commonly based on groundwater resources. The study revealed that the minerals such as apatite, fluorite, biotite and pyroxene in the hornblende–biotite gneiss formation contribute fluoride ions to the groundwater system due to water–rock interaction mechanism. The Durov diagram depicted that dissolution of silicate minerals and cation exchange are the foremost hydrogeochemical activities, which decide the overall chemical composition of groundwater in this region. The ionic concentrations including fluoride increased with respect to depth of occurrence of groundwater. Escalation of the water table due to monsoon recharge and artificial recharge through a check dam decreased the total dissolved solids and fluoride ion concentration. The investigation conducted around the existing check dam at Kaldurai village highlighted that the fluoride concentration is below the allowable limit of 1.5 mg/l (WHO in World health statistics 2017: monitoring health for the SDGs, Sustainable Development Goals. World Health Organization, Geneva, 2017) in the wells closer to the check dam toward the downstream side. The concentration increased with distance, which lead the groundwater unsuitable for consumption. Therefore, it is recommended to implement the managed aquifer recharge using check dams in the other parts of the basin to enrich the quantity and applicability of groundwater.

     

Time evolution of the matter content of the expanding universe in the framework of Brans-Dicke gravity

A cosmological model has been constructed in the framework of Brans-Dicke(BD) gravity,based on an inter-conversion between matter and dark energy, for a spatially flat universe in the era of pressureless dust. To account for the non-conservation of the matter content, a function of time f(t) has been arbitrarily put into the expression for the density of matter(ρa^3= f(t)ρ_0 a_0~3). By definition, f(t) is proportional to the matter content of the universe. Using suitable ansatzes for the scale factor and scalar field, the functional form of f(t) has been determined from the BD field equations. The scale factor has been so chosen that it would cause a signature flip in the deceleration parameter with time. The function f(t) decreases monotonically with time, indicating a transformation of matter into dark energy. The time dependence of the proportions of matter and dark energy in the universe has been determined. The effect of non-conservation of the matter content upon various cosmological parameters has been explored in the present study. Two models of matter-energy interaction have been proposed and f(t) has been expressed as a function of their interaction term. The dark energy equation-of-state(EoS) parameter has been expressed and analyzed in terms of f(t).     

Study of morphology and suspended sediment of Bhopal Upper Lake using spatial simulation technique and remote sensing data

The scope of this research was to study lake morphology using spatial simulation technique, to develop revised elevation-capacity curve, to develop elevation-water spread area curve, to study the relation between suspended sediment and remote sensing satellite data, and to estimate suspended sediment load in the lake using a Geographic Information System coupled with ground truth. The study area was the Bhopal Upper Lake, which has been classified as one of the major wetlands in India by the Ministry of Water Resources, India. A precise digital elevation model was created using 0.5 meter interval contour information collected from bathometric surveys. Water-spread areas at different water levels were simulated spatially in a Geographic Information System (GIS) through the neighbourhood connectivity operator. Revised elevation-capacity curve and elevation-area curve of the lake were prepared using the simulated results. Simulated water spread area at full tank level (FTL) was compared with the actual water spread area delineated using remote sensing data. Water samples at different locations of the lake were collected and located using the Global Positioning System (GPS) instrument. These samples were analysed in the laboratory for suspended sediment concentration. Different image processing techniques were applied to LANDSAT 5 TM satellite digital data (except thermal band). Correlation between radiance values of band 2 and suspended sediments was established and a positive linear equation was found to fit the data best. Spatial distribution of suspended sediment load was estimated using the developed regression equation and band 2 radiance image of the complete lake. Total suspended sediment load and loss of capacity at full tank level were computed.     

Gas hydrates in the western deep-water Ulleung Basin, East Sea of Korea

Geophysical surveys and geological studies of gas hydrates in the western deep-water Ulleung Basin of the East Sea off the east coast of Korea have been carried out by the Korea Institute of Geoscience and Mineral Resources (KIGAM) since 2000. The work included a grid of 4782 km of 2D multi-channel seismic reflection lines and 11 piston cores 5–8 m long. In the piston cores, cracks generally parallel to bedding suggest significant in-situ gas. The cores showed high amounts of total organic carbon (TOC), and from the southern study area showed high residual hydrocarbon gas concentrations. The lack of higher hydrocarbons and the carbon isotope ratios indicate that the methane is primarily biogenic. The seismic data show areas of bottom-simulating reflectors (BSRs) that are associated with gas hydrates and underlying free gas. An important observation is the numerous seismic blanking zones up to 2 km across that probably reflect widespread fluid and gas venting and that are inferred to contain substantial gas hydrate. Some of the important results are: (1) BSRs are widespread, although most have low amplitudes; (2) increased P-wave velocities above some BSRs suggest distributed low to moderate concentration gas hydrate whereas a velocity decrease below the BSR suggests free gas; (3) the blanking zones are often associated with upbowing of sedimentary bedding reflectors in time sections that has been interpreted at least in part due to velocity pull-up produced by high-velocity gas hydrate. High gas hydrate concentrations are also inferred in several examples where high interval velocities are resolved within the blanking zones. Recently, gas hydrate recoveries by the piston coring and deep-drilling in 2007 support the interpretation of substantial gas hydrate in many of these structures.     

Governing fisheries as complex adaptive systems

Fisheries are complex human-in-nature systems. The conventional approach to fisheries systems has been to treat them as predictable and controllable. As complex systems they are neither of the two and have to be approached differently. Complex systems often exhibit the capacity to self-organize or adapt, even without outside influence. If this is true of fisheries, it should lead to a radically different approach to management of fisheries systems that places much emphasis on enabling self-organization, learning and adaptation. Conceptual and practical frameworks for enabling activities are needed.     

Genetic diversity and population structure of the size‐selectively harvested owl limpet,Lottia gigantea

Size‐selective harvesting can elicit a genetic response in target species through changes in population genetic subdivision, genetic diversity and selective regimes. While harvest‐induced genetic change has been documented in some commercially important species through the use of historic samples, many commonly harvested species, such as coastal molluscs, lack historic samples and information on potential harvest induced genetic change. In this study, we have genotyped six microsatellite markers from populations across much of the California mainland range of the size‐selectively harvested owl limpet (Lottia gigantea) to explore the genetic structure and diversity of this species. We found no significant genetic structure or differences in genetic diversity among populations of L. gigantea. Our results suggest high gene flow among populations and that differences in life history, demography, and body size previously observed between protected and exploited populations is largely due to phenotypic plasticity. From a conservation perspective, if proper actions are taken to curb harvesting, then exploited populations should be able to return to their pre‐impact state given sufficient time.