Geohydrological conditions of the Deccan Trap flow around Saugor (M.P.), India

The geological formations that occur around Sagar consist of Upper Rewa quartzitic sandstones of Vindhvan age and nine Deccan Trap flows with three main inter-trappean bands. Most of the villages around Sagar depend upon the flow No. 5 for their water supplies. This flow forms valleys which may occur either in between the Vindhyan hills or Vindhyan hills and Trap hills, or Trap hills. To evaluate the geo-hydrological conditions of this flow under different topographic and stratigraphic controls, detailed geologic, water-shed and water table maps were prepared and analysed, after taking into consideration rain fall data for a period of sixty years. The villages selected for studies include the farm-lands of Richonda which occur in between the Vindhyan hills and Kudari, which occurs in between the Trap and Vindhyan hills. Villages like Patkui and Bhainsa, occurring on either side of the surface water divide of the same flow, are also taken into consideration. Water table maps for these villages were prepared once before the onset of rains and the second time immediately after the rains, on a scale of 16″ to a mile at 1 foot contour intervals. From such studies made on this flow, the following conclusions have been arrived at:

1. Where a flow occurs in adjacent Deccan Trap valleys separated by a long continuous Vindhyan ridge, the Vindhyan ridge may act as an underground barrier, separating the ground water body of the flow into two distinct units, and the upper unit may give rise to springs on that valley side of the Vindhyan having the lower elevation.
2. Where the Vindhyan ridge loses its height and disappears below the flow, the adjacent separate water bodies of this flow merge into a single water body. The portion of the Vindhyan ridge that occurs below the ground still continues to act as barrier for the water bodies of the lower flows.
3. Where the flow occurs over a large area, but at places is overlaid by younger flows, giving rise to hills with distinct water-shed characteristics, the water body of the flow is generally continuous on either side of the hills, immediately after the rains. This, however, gets disrupted into separate water bodies during summer months and it is found to recede in the slope direction; nevertheless, the trend of recession is controlled locally by the levels at which the porous zone of a flow occurs.
4. Where the continuity of the flow is disrupted due to denudation, producing valleys, the continuity of the water table of that flow is also interrupted.
5. On either side of a distinct surface water divide of a flow, the ground water bodies occur as separate units in the flow.

     

Meta-heuristic ant colony optimization technique to forecast the amount of summer monsoon rainfall: skill comparison with Markov chain model

Forecasting summer monsoon rainfall with precision becomes crucial for the farmers to plan for harvesting in a country like India where the national economy is mostly based on regional agriculture. The forecast of monsoon rainfall based on artificial neural network is a well-researched problem. In the present study, the meta-heuristic ant colony optimization (ACO) technique is implemented to forecast the amount of summer monsoon rainfall for the next day over Kolkata (22.6°N, 88.4°E), India. The ACO technique belongs to swarm intelligence and simulates the decision-making processes of ant colony similar to other adaptive learning techniques. ACO technique takes inspiration from the foraging behaviour of some ant species. The ants deposit pheromone on the ground in order to mark a favourable path that should be followed by other members of the colony. A range of rainfall amount replicating the pheromone concentration is evaluated during the summer monsoon season. The maximum amount of rainfall during summer monsoon season (June—September) is observed to be within the range of 7.5–35 mm during the period from 1998 to 2007, which is in the range 4 category set by the India Meteorological Department (IMD). The result reveals that the accuracy in forecasting the amount of rainfall for the next day during the summer monsoon season using ACO technique is 95 % where as the forecast accuracy is 83 % with Markov chain model (MCM). The forecast through ACO and MCM are compared with other existing models and validated with IMD observations from 2008 to 2012.     

On multifractality and synchronization of nonlinear stellar pulsators

Simple models of nonlinear stellar pulsation, whose temporal behavior may reproduce some of the observed features of different classes of variable stars, have been studied. The temporal behavior of dynamical variables of these models exhibits a cascade of period doubling chaos, depending on the specific values of the various control parameters. A multifractal detrended fluctuation analysis (MFDFA) method is further used to identify the scaling behavior of such synthetic time series. The MFDFA of the considered time series, for various models of nonlinear stellar pulsation, shows that the observed multifractal nature is due to long-range correlations. The pulsating star with increased nonadiabaticity and the star with increased convective luminosity, as represented by the simulated data, is shown to possess a strange attractor with noninteger correlation dimension that lies between 2–3. Also the problem of synchronization in coupled nonlinear pulsation models has been investigated using permutation entropy—a complexity measure of the system. The computed order parameter, Γ, representing the correlation of computed permutation entropy for different segments of the simulated time series of displacement of two nonidentical oscillators, has been further used to find the critical coupling parameter for general synchronization of the oscillators.     

Overcoming source limitations in drainage delineation by combining the streams of toposheet and DEM in river morphometric studies

A potential head ward retreat landslide area was identified in Munnar, a hill station in Western Ghats of Kerala, India. This imminent landslide was suspected to be formed in three different stages viz., evolution of plateau region, upliftment of the plateau region and the consequent slope modification which ultimately facilitated landslide occurrence. Geophysical study through vertical electrical sounding reveals that more than 11 m thick soil is still left in an overhanging position in the crown portion of the landslide and the thickness continues to the top of that ridge. In the event of high rainfall, the land can fail as there is no toe support, and the slope angle is >40º. This area is adjacent to a college building and in the event of any further landslide, the consequence will be high. Slope stability analysis using one-dimensional infinite slope stability model reveals that the entire area occupied by the college and the adjacent areas are unstable even in dry conditions. Rainfall threshold analysis shows that the landslide occurred due to very high amount of a 5-day antecedent rainfall rather than a daily rainfall during the monsoon. All these point towards a pressing requirement of landslide management practices in this area. This study also attempts to suggest a few management practices to minimize the effect of landslides.     

The sensitivity to the microphysical schemes on the skill of forecasting the track and intensity of tropical cyclones using WRF-ARW model

The Advanced Research WRF (ARW) model is used to simulate Very Severe Cyclonic Storms (VSCS) Hudhud (7–13 October, 2014), Phailin (8–14 October, 2013) and Lehar (24–29 November, 2013) to investigate the sensitivity to microphysical schemes on the skill of forecasting track and intensity of the tropical cyclones for high-resolution (9 and 3 km) 120-hr model integration. For cloud resolving grid scale (<5 km) cloud microphysics plays an important role. The performance of the Goddard, Thompson, LIN and NSSL schemes are evaluated and compared with observations and a CONTROL forecast. This study is aimed to investigate the sensitivity to microphysics on the track and intensity with explicitly resolved convection scheme. It shows that the Goddard one-moment bulk liquid-ice microphysical scheme provided the highest skill on the track whereas for intensity both Thompson and Goddard microphysical schemes perform better. The Thompson scheme indicates the highest skill in intensity at 48, 96 and 120 hr, whereas at 24 and 72 hr, the Goddard scheme provides the highest skill in intensity. It is known that higher resolution domain produces better intensity and structure of the cyclones and it is desirable to resolve the convection with sufficiently high resolution and with the use of explicit cloud physics. This study suggests that the Goddard cumulus ensemble microphysical scheme is suitable for high resolution ARW simulation for TC’s track and intensity over the BoB. Although the present study is based on only three cyclones, it could be useful for planning real-time predictions using ARW modelling system.     

Probable existence of a Gondwana transcontinental rift system in western India: Implications in hydrocarbon exploration in Kutch and Saurashtra offshore: A GIS-based approach

The Gondwanaland assembly rifted dominantly during Late Carboniferous–Early Permian forming several intracratonic rift basins. These rifts were subsequently filled with a thick sequence of continental clastic sediments with minor marine intercalations in early phase. In western part of India, these sediments are recorded in enclaves of Bikaner–Nagaur and Jaisalmer basins in Rajasthan. Facies correlatives of these sediments are observed in a number of basins that were earlier thought to be associated with the western part of India. The present work is a GIS based approach to reconnect those basins to their position during rifting and reconstruct the tectono-sedimentary environment at that time range. The study indicates a rift system spanning from Arabian plate in the north and extending to southern part of Africa that passes through Indus basin, western part of India and Madagascar, and existed from Late Carboniferous to Early Jurassic. Extensions related to the opening of Neo-Tethys led to the formation of a number of cross trends in the rift systems that acted as barriers to marine transgressions from the north as well as disrupted the earlier continuous longitudinal drainage systems. The axis of this rift system is envisaged to pass through present day offshore Kutch and Saurashtra and implies a thick deposit of Late Carboniferous to Early Jurassic sediments in these areas. Based on analogy with other basins associated with this rift system, these sediments may be targeted for hydrocarbon exploration.     

Structural controls on topography and river morphodynamics in Upper Assam Valley,India

The basement in Upper Assam foreland basin exhibits a typical flexure pattern. An elongated continuous subsurface basement high has developed between Himalaya and Naga-Patkai ranges. A few prominent basement lows have developed adjacent to the foothill regions. It is noticed that the general topographic slope near the foothill regions is not only controlled by aggradation process, but also influenced by the flexured basement of the region. The basement lows have influenced the overlying topography significantly. Rivers flowing over those regions have shown unidirectional lateral migration. North bank tributaries like Subansiri, Jiadhal and Dikrang have been affected by the Subansiri basement low. Coseismic subsidence of sediments over Subansiri basement low had resulted subsidence of the North Lakhimpur-Ranga Nadi region in 1950 Assam earthquake. Some south bank tributaries like Disang and Dikhow have been affected by Nazira basement low. Topographic elevation along the Subansiri river is lower than that part of the Brahmaputra located south of Majuli. This typical topographic setting of the region makes the mouth of the Subansiri river and Majuli region highly susceptible to erosion.     

Co-composting of cow dung,municipal solid waste,roadside pond sediment and tannery sludge: role of human hair

In general, farmers from developing countries often use several feeding mixtures based on materials available in their vicinity resulting in a final poor-quality compost product. Human hair as a composting feed could impact on the nutrient status in prepared compost. In this study, the effect of different amount of human hair to tannery sludge, roadside pond sediment, municipal solid waste and cow dung was investigated during 70-day composting cycle. Human hair addition increased N, P and K from 1.36 to 22.85, 53.06 to 189.80 and 4.13 to 39.26%, respectively, over control. Total metal and arsenic contaminations were significantly higher than in control but lower than the Indian permissible limit. Highest amount of human hair in composting feed indicated that the germination index for tea seed (Camellia sinensis L.) was less than 80% reflecting the possible remaining phytotoxic substances. Redundancy analysis revealed that there was a significance influence of the physico-chemical variables on bacterial community.     

Groundwater appraisal of Dhekiajuli,Assam, India: an insight of agricultural suitability and arsenic enrichment

The present work is an effort to develop an appraisal of the hydrogeochemical regime for the aquifers of Dhekiajuli, Sonitpur district, Assam, which is imperative considering: (i) excessive use of groundwater for irrigation; (ii) reported high arsenic (As) contamination; (iii) application of fertilizer is an inevitable process undergoing in this region to achieve higher yield owing to deteriorating water quality; and (iv) study area being the location of many tea estates of Assam, that export tea in many foreign countries. The highest As concentration of 44.39 µg/L was detected in this study (Bachasimalu and Sitalmari region), implying high As-contaminated aquifers being used for drinking and irrigation purposes in the area. The relative abundance pattern of major cations and anions was in the order of Na⁺ > Mg²⁺ > Ca²⁺ > K⁺ and HCO₃ ^? > Cl^? > SO₄ ^2?, respectively. Majority of the samples belong to Na⁺–K⁺–Cl^?–HCO₃ ^? and mixed water type. Closer inspection of Piper plot reveals that a higher As value (>40 µg/L) was prevalent in HCO₃ ^? water type. Results of hydrogeochemical plots suggest silicate and carbonate weathering, ion exchange and anthropogenic activities to be the dominant processes governing groundwater contamination, including As which is further supported from PCA loadings. The Singri area to the east of the affected areas and adjacent to the Brahmaputra River has oxic aquifers owing to the absence of mass deposition of younger sediments, while reducing conditions prevails in the Bachasimalu and Sitalmari region. High positive correlation between As and Fe (r = 0.83**) and a negative correlation between ORP and Fe (r = ?0.68**) further add that Fe (hydr)oxides are the direct source of As release in the affected region, the mechanism being reductive hydrolysis of such (hydr)oxides. The study implies that although groundwater is suitable for irrigation use, there is a high probability of As getting into the food chain through tea and other edible plants irrigated with As-contaminated water; thus, the area has a maximum probability of facing health hazards caused by As-contaminated groundwater.