Swarnalatha K.,College of Engineering, Trivandrum |
Letha J.,Government of Kerala
Journal of Urban and Environmental Engineering | Year: 2013
Risk analysis of urban aquatic systems due to heavy metals turns significant due to their peculiar properties viz. persistence, non-degradability, toxicity, and accumulation. Akkulam Veli (AV), an urban tropical lake in south India is subjected to various environmental stresses due to multiple waste discharge, sand mining, developmental activities, tourism related activities etc. Hence, a comprehensive approach is adopted for risk assessment using modified degree of contamination factor, toxicity units based on numerical sediment quality guidelines (SQGs), and potentialecological risk indices. The study revealed the presence of toxic metals such as Cr, Cd, Pb and As and the lake is rated under 'low ecological risk' category. © 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Swarnalatha K.,College of Engineering, Trivandrum |
Letha J.,Government of Kerala
Environmental Earth Sciences | Year: 2013
The heavy metal burden of Akkulam-Veli Lake, a shallow lake in southern part of India, is investigated through the analysis of surface sediments. The average concentrations of heavy metals such as lead, chromium, nickel, copper, zinc, cobalt, iron, and manganese were determined at selected stations. The degree of contamination of selected stations was evaluated using indices such as enrichment factor, contamination factor, and pollution load index and compared with sediment quality guidelines. Statistical analysis is carried out by correlation analysis and hierarchical clustering analysis to identify relatively homogeneous groups of cases. The results of this study indicate severe contamination at most of the stations selected. The degree of contamination of the lake could be rated as 'moderate' to 'strong'. The average pollution load index shows progressive deterioration of sediment quality indicating 'risk' on the aquatic environment and ecosystems of the lake. © 2012 Springer-Verlag.
Swarnalatha K.,College of Engineering, Trivandrum |
Letha J.,Government of Kerala
Environmental Monitoring and Assessment | Year: 2014
Environmental effects due to continuous accumulation of hazardous materials like heavy metals in the surface sediments of lake systems can stress fragile ecosystems. Elucidating the mechanisms influencing the concentration and distribution of heavy metals becomes vital in formulating lake management strategies to preserve the quality of the water environment. Studying of the effect of seasonal variations on surface sediments will help in understanding the different factors and sources contributing and diluting these persistent pollutants. In this study, heavy metal pollution in a tropical shallow lake (Akkulam-Veli) in South India was investigated by monitoring the seasonal variations of heavy metals and major elements in surface sediments. The metallic pollutants (Cr, Ni, Co, Cu, Zn, Pb, Fe, and Mn) and major elements (Si, Ti, Al, Ca, Mg, Na, K, and P (measured as oxides) in the surface sediments of this lake were monitored during four consecutive seasons. The results were subjected to correlation analysis and principal component analysis to study the interrelationships of different parameters as well to determine the possible origin of pollutants. Although metal concentrations were found to be unaffected by seasonal variations, the factors contributing to occurrence of these heavy metals were found to be affected by seasonal fluctuations. © 2014 Springer International Publishing.
Baiju C.K.,Government of Kerala |
Ajaykumar B.,Government of Kerala |
Gopinath G.,Center for Water Resources Development and Management |
Ramkumar T.,Annamalai UniversityTamil Nadu
International Journal of Earth Sciences and Engineering | Year: 2015
In the Indian context, perhaps the most important single climate factor is the monsoon, which determines the lives, ecology and economics of the region. The late Holocene was marked by multiple short-term phases of aggradations and degradations of monsoon, which were not spatially synchronous. The present study illustrates the imprints of increased Holocene monsoon around 3000YBP (Years Before Present) over the Indian subcontinent as revealed from the terrigenous proxy record preserved in the Periyar Plateau (PP) of the Western Ghats by geochemical analysis and radiocarbon dating. The mode of deposition of the stratigraphic sequences, geochemical properties of the sedimentary formations and their age of deposition clearly suggested that the Plateau had not preserved the terrigenous proxy records of the Holocene Climatic Optimum during 8500YBP – 6000YBP. Rather, the neotectonic event of 4000YBP reported from many parts of the Southern Peninsular region might have played a vital role in modifying the surface configuration of this highland Plateau and favouring the later deposition. The study concluded that the late Holocene monsoon episodes and climatic fluctuations over the regions falling along the south western Peninsular India were influenced by not only the solar insolation regimes of both northern and southern hemisphere, but also the presence of Western Ghats in facilitating the orographically enhanced precipitation by intercepting the southwest trade winds. © 2014 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
Gopinath A.K.,Government of Kerala |
Radhakrishnan T.,Indian Institute of Information Technology and Management Gwalior
WIT Transactions on Ecology and the Environment | Year: 2011
Uninstrumented watersheds pose a problem to the practising engineers when attempts to mitigate the flood waters of these watersheds are taken up. The problems become complex when one encounters a situation where there is no demarcation available for the watersheds in a region, nor historic data available for any meteorological factors of the region. Practising engineers usually adopt unscientific rational or empirical methods for estimating the design flood. But these approaches lead to overestimation or under estimation of floods, since such approaches do not take into account the hydro-meteorological factors of the watershed under consideration. Hence a more scientific approach for flood estimation is required for a cost effective design of the stream networks. This aspect is taken up through this study. The case study pertains to mitigation of flood waters in the Onattukara region of Kerala State, India which encompasses all these complexities. Twelve micro watersheds in this region were identified and this was made possible through identification of drainage networks in the area and digitization of the same on GIS platform. A scientific approach which takes into account all the above mentioned factors for ungauged catchments and developed by Central Water Commission (CWC), Govt of India was applied for this region. To bring out the effectiveness of this method, a comparison of this method with the conventional method on estimation of flood discharge is made. The flood discharge values are estimated with the existing empirical and rational formulae (Conventional method) for this region. The comparison with that obtained from the CWC model has considerable deviation. © 2011 WIT Press.
Rajan A.K.,National Coir Research and Management Institute |
George R.,Government of Kerala |
Prakash R.R.,Government of Kerala
44th Conference and Expo of the International Erosion Control Association: Environmental Connection 2013 | Year: 2013
A retaining wall 20 m long × 2 m wide × 2 m height with thin corrugated panel (asbestos) as the facing was constructed. Woven coir geo textiles with mesh size 25mm (740 g/m2) and bamboo reapers (2m long × 0.35 m wide × 0.01m thick) were used as the reinforcement structure at a vertical spacing of 0.60 m. The natural lateritic soils at the site with specific gravity 2.4 and angle of internal friction 30° was used as the backfill. Two layers each of 0.25m was made compact in such a way that it attains maximum dry density and optimum moisture content. It was observed that for the bottom layer the maximum dry density is greater and the optimum moisture content is less when compared to the top and middle layers. Also the compaction curve shifts towards the left and moves higher for the bottom layer compared to the top and middle layers. The variation from the normalized horizontal deformation of the wall against the height of the wall in 11 days post construction period had an increase in the deformation for the entire height of the wall due to pore pressure developed after heavy rainfall. After 15 days the pore pressure dissipated. A similar behaviour was seen at 20 days and 25 days post construction period. Immediately after construction of the wall, a zigzag pattern in deformation was observed. At 60 and 80 days post-construction period, the deformation of the wall has decreased to the initial position. The maximum horizontal deformation of the wall was 1.9 per cent of height of the wall, observed at 1.75 m height at 20 days post-construction period. A similar trend was observed for various sections. The rate of increase in deformation was more during the initial period of 25 days. At 60 days post construction period, a decrease in deformation was observed with a slight increase at 80 days. A maximum settlement of 4.03 per cent to 4.2 per cent at various sections were observed 80 days post-construction period. The maximum normalized settlement of the retaining wall was 4.2 per cent, observed at the bottom most layer. It was seen that the settlement of the wall increases with time. The rate of increase in settlement was more during the initial period of 25 days and later the settlement almost became constant. The deformation and settlement of the wall facing was determined using total station. The retaining wall was intact even after 11 months of its construction. The effective use of reinforcements in low height walls has proved that a thin flexible facing can be used to prevent the erosion of backfill from the structure.
Zachariah A.,Government of Kerala |
Zong J.-C.,The Sidney Kimmel Comprehensive Cancer Center |
Long S.Y.,The Sidney Kimmel Comprehensive Cancer Center |
Latimer E.M.,National Elephant Herpesvirus Laboratory |
And 3 more authors.
Journal of Wildlife Diseases | Year: 2013
Up to 65% of deaths of young Asian elephants (Elephas maximus) between 3 mo and 15 yr of age in Europe and North America over the past 20 yr have been attributed to hemorrhagic disease associated with a novel DNA virus called elephant endotheliotropic herpesvirus (EEHV). To evaluate the potential role of EEHV in suspected cases of a similar lethal acute hemorrhagic disease occurring in southern India, we studied pathologic tissue samples collected from field necropsies. Nine cases among both orphaned camp and wild Asian elephants were identified by diagnostic PCR. These were subjected to detailed gene subtype DNA sequencing at multiple PCR loci, which revealed seven distinct strains of EEHV1A and one of EEHV1B. Two orphan calves that died within 3 days of one another at the same training camp had identical EEHV1A DNA sequences, indicating a common epidemiologic source. However, the high level of EEHV1 subtype genetic diversity found among the other Indian strains matches that among over 30 EEHV1 strains that have been evaluated from Europe and North America. These results argue against the previous suggestions that this is just a disease of captive elephants and that the EEHV1 virus has crossed recently from African elephant (Loxodonta africana) hosts to Asian elephants. Instead, both the virus and the disease are evidently widespread in Asia and, despite the disease severity, Asian elephants appear to be the ancient endogenous hosts of both EEHV1A and EEHV1B. © Wildlife Disease Association 2013.
Sheela S.,National Institute of Technology Calicut |
Ganesan N.,Government of Kerala
Indian Concrete Journal | Year: 2012
This paper reports the flexural behaviour and ultimate load carrying capacity of ferrocement flexural elements having a span of 3 m. The investigation were for (i) two cross sectional shapes ; channel and trapezoidal (ii) mixes with and without styrene butadiene rubber (SBR) (iii) woven wire mesh of 4 x 20 gauge and 6 x 22 gauge and (iv) the number of wire mesh layers. The results indicate that the addition of polymer in the mortar matrix and the use of 4x20 gauge wire mesh, instead of 6x 22 gauge wire mesh, significantly increased the load carrying capacity of the elements. A method for the predicting the ultimate load carrying capacity of the ferrocement flexural elements is also proposed.
Sheel A.,Government of Kerala
Indian Historical Review | Year: 2015
The study draws upon both unpublished as well as published sources to describe the structure of, and changes in, agricultural trade and markets at the regional and local level in the British India districts of Shahabad and Gaya, spanning parts of the current state of Bihar, in northern India during 1800–1920.Agricultural trade and markets during the period under study were largely shaped by the logic of subsistence agriculture, available infrastructure, the land rent payment system and patterns of demand. There were six striking developments. First, the construction of all-weather roads and the railway, part of the modern public infrastructure put in place soon after the administration of the two districts came directly under the British Crown in 1858, gave a great fillip to trading activity. Old trade routes lost their pre-eminence, as new channels took root. The modern infrastructure also tended to integrate the markets in the two districts on the one hand, while increasing the pulls of external markets on the other. This was reflected in greater price equalisation between markets. Second, notwithstanding greater market integration and increased stability in annual farm yields on account of the construction of modern irrigation canals that reduced the reliance on monsoonal precipitation, sharp seasonal fluctuations in the market price of food grains continued. Third, there was a sustained secular upswing in agricultural prices practically throughout the period, with the terms of trade moving in favour of agriculture, as the entry of mass produced wage goods into local markets had a deflationary impact on industrial goods. This, along with the growing depth of trade and markets, and changes in the land rent payment system, facilitated the rise of a new social group that became a new source of demand and was to subsequently play a major role in the emerging political economy. Fourth, there were three inter-dependent tiers of trading activity—long-distance trade conducted by arhatiyas, trade between major trade centres conducted by ladu beparis and trade within the village dominated by the grihasta bepari, the chief source of agricultural credit and frequently an agriculturist himself. Modern infrastructure transformed the conduct of long-distance trade, even as the pattern of short-distance trade and credit remained remarkably resilient. The fifth feature was the sharp and sudden expansion of the range of products traded in the market, as the latter was drawn into the emerging global system with the first industrial nation at the epicentre. While locally produced handicraft products like indigenous cotton cloth and paper lost their former importance, trade in agricultural commodities and imported industrial goods grew. Sixth, and last, was the increase in the monetisation of the rural economy at the cutting edge as the traditional system of paying rent in kind was commuted to cash. © 2015 ICHR SAGE Publications.
Bhagyalekshmi S.,Mahatma Gandhi University |
Mohan M.,Mahatma Gandhi University |
Sreedharan K.,Mahatma Gandhi University |
Ajaykumar B.,Government of Kerala
Arabian Journal of Geosciences | Year: 2015
Soil piping (tunnel erosion) is a soil-related natural disaster. It is a type of sub-surface erosion, which involves the hydraulic removal of sub-surface soil causing the formation of an underground passage in landscape. Soil piping significantly affects the most responsive run-off systems of the humid tropics. Southern parts of the Western Ghats have recorded seven incidents of this phenomenon within a period of 1 year, starting from August 2010 to August 2011. Out of the seven incidents recorded from the Ghats regions falling in Idukki District of Kerala, south India, the main aspects and parameters of four locations were evaluated and correlated by synthesizing the physical, chemical, geological and hydrological parameters. The evaluation showed a similar expression of physical, chemical and hydrological components of soil at the sites 1, 2 and 4, which does not normally favour the phenomena of soil piping, while site 3 has chemical components favouring its development. Even though the pipe outlets were observed at or near the foothills, the mechanism behind the recharging is to be clarified further more. The study reveals that the phenomenon has been recorded from a variety of geographical entities with no common contributing system, except the intensity of rainfall and vicinity to prominent structural controls. Hence, the increased periodicity of occurrence of the incidents is attributed to the stress-induced dilatation of the sub-surface water-bearing formations before and after a series of mild tremors recorded contemporaneously from Idukki District, Kerala. © 2015 Saudi Society for Geosciences