Modelling of tidal hydrodynamics for a tropical ecosystem with implications for pollutant dispersion (Cohin Estuary, Southwest India)   总被引：1，自引：0，他引：1  

Kizhakkepat Kalathil Balachandran  Guddemmari Sidha Reddy  Chenicherry Revichandran  Kotamarpi Srinivas  Panachikkal Ramakrishnan Vijayan  Tony Joseph Thottam 《Ocean Dynamics》2008,58(3-4):259-273

Tidal circulation in the Cochin Estuary, a moderately polluted estuary along the southwest coast of India, was studied using a 2D hydrodynamic model. The predicted tides and currents showed very good agreement with measured tides. Particle trajectories and residual currents computed from the model have been used to classify the study region into three zones: northern estuary, central estuary, and southern estuary. The central estuary is dynamic, whereas the other two zones are relatively weak. An amplification of measured tides in the south estuary during March indicates the presence of standing waves caused by the hydraulic barrier at Thanneermukkom. Model results suggest that the northern and southern zones are sensitive to environmental pollution. The present level of pollution in the northern estuary is due to the direct release of industrial effluents into the river Periyar, which can be minimized if they are brought down to central estuary for disposal. The concept of different zones in the estuary will be useful to planners in protecting the vulnerable regions of this productive ecosystem from human interventions.  相似文献   

Biochemical and stable carbon isotope records of mangrove derived organic matter in the sediment cores     

M. N. Manju  P. Resmi  C. S. Ratheesh Kumar  T. R. Gireeshkumar  N. Chandramohanakumar  Manju Mary Joseph 《Environmental Earth Sciences》2016,75(7):565

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Heavy metal accumulation in the surficial sediments along southwest coast of India     

P. Udayakumar  J. Jean Jose  K. Anoop Krishnan  C. S. Ratheesh Kumar  M. N. Manju  P. M. Salas 《Environmental Earth Sciences》2014,72(6):1887-1900

Concentration and distribution of heavy metals (Cd, Cr, Cu, Hg, Ni, Pb and Zn) in surface sediments collected from five stations located along the southwest coast of India were investigated seasonally to assess whether there is insidious buildup of heavy metals. Spatial variation was in accordance with textural characteristics and organic matter content. The concentration of the metals in sediments of the study area followed the order: Zn > Cr > Ni > Cu > Pb > Cd > Hg. The use of geochemical tools and sediment quality guidelines to account for the magnitude of heavy metal contamination revealed high contamination in monsoon and impoverishment during post-monsoon. Estimated total metal concentrations in the present investigation were comparable with other studies; however, concentrations of Ni and Zn were higher than that of other coastal regions. Concentrations of metals in sediment largely exceed NOAA effects range:low (e.g., Cu, Cr, Hg) or effects range:median (e.g., Ni) values. This means that adverse effects for benthic organisms are highly probable.  相似文献   

A lattice type model for particulate media     

Muniram Budhu  S. Ramakrishnan  George Frantziskonis 《国际地质力学数值与分析法杂志》1999,23(7):647-671

In this paper, a lattice-type model to simulate the micro-mechanical behaviour of particulate/granular media is presented. In this numerical model, a particulate assembly is simulated as a lattice/truss. Nodes located at contacts between a particle and its neighbours are linked by bars to each other. Each particle is represented by a lattice within its microstructure and particle interact through load transfer at the nodes. Constraints are prescribed at the nodes to describe active, deactivated and reactivated contacts. When a particulate assembly develops into a mechanism (deformation with zero incremental load), further deformation is simulated through a framework that describes the kinematics of the particles (sliding, rolling and rotation of particles). This framework is formed by introducing nodes at the particle centroids and linking them with bars. Bars-linking particles with a non-sliding contact are assigned large stiffnesses relative to bars linking particles with a sliding contact. Numerical tests are conducted on two-dimensional assemblies of disks, arranged as very loose and very dense packing under simple shear loading conditions. The results concord with the results of numerical tests conducted using the discrete element method and with photoelastic experiments. Additionally, the model is applied to study the effects of initial imperfections caused by particles with low elastic modulus. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献