scholarly journals Hydrogeology of Brahmaputra Basin, India

2003 ◽  
Vol 28 ◽  
Author(s):  
Barendra Purkait
Keyword(s):  
Ground Water ◽  
Water Table ◽  
Land Surface ◽  
Flood Plain ◽  
Water Levels ◽  
The South ◽  
Drainage Pattern ◽  
The North ◽  
The World ◽  
Brahmaputra Basin

The Ganga-Brahmaputra river system together forms one of the largest deltas in the world comprising some 59570 sq km. The waterpower resources of the Brahmaputra have been presumed to be the fourth biggest in the world being 19.83 x 103 m3s1. The entire lower portion of the Brahmaputra consists of a vast network of distributary channels, which are dry in the cold season but are inundated during monsoon. The catchment area of the entire river is about 580,000 sq km, out of which 195,000 sq km lies in India. The maximum discharge as measured at Pandu in 1962 was of the order of 72800 m3 s-1 while the minimum was 1750 m3 s-1 in 1968. The drainage pattern in the valley is of antecedent type while the yazoo drainage pattern is most significant over the composite flood plain to the south of the Brahmaputra. The Brahmaputra valley is covered by Recent alluvium throughout its stretch except a few isolated sedimentary hills in the upper Assam, inselbergs/bornhardt of gneissic hills in the Darrang, Kamrup and Goalpara districts and a few inlying patches of Older Alluvium in the Darrang and Goalpara districts. The basin is very unstable. The present configuration of the basin is the result of uplift and subsidence of the Precambrian crystalline landmasses. Four geotectonic provinces can be delineated in the N-E India through which the Brahmaputra flows. These are bounded by major tectonic lineaments such as the basement E-W trending Dauki fault, a NE-SW trending structural feature of imbricate thrusts known as 'belt of Schuppen' and the NW-SE trending Mishmi thrust. Hydrogeologically, the Brahmaputra basin can be divided into two distinct categories, viz(a) dissected alluvial plain and (b) the inselberg zone. The first category is rep resented in the flood plain extending from the south of Sub-Himalayan piedmont fan zone in the north to right upto the main rock promontory of Garo Hills and Shillong Plateau. The inselberg zone is characterized by fractured, jointed and weathered ancient crystalline rocks with interhill narrow valley plains, consisting of thin to occasionally thick piles of assorted sediments. From the subsurface lithological data, two broad groups of aquifers are identified. These are i) shallow water table and ii) deeper water table or confined ones, separated by a system of aquicludes. The shallow aquifer materials, in general, consist of white to greyish white, fine grained micaceous sand and the thickness ranges from 1.2 to 10.3 m. The sand and clay ratio varies from 1: 2.5 to 1:26. The bedrock occurs at depth ranges of 30.4 to 39.5 m. The materials of the deeper aquifers comprise grey to greyish white, fine to medium grained sand. The sand and clay ratio varies from 1:2 to 1:7. The effective size of the aquifer materials varies from 0.125 to 0.062 mm with uniformity co-efficient around 4.00, porosity 38 to 42%, co-efficient of permeability 304 to 390 galls per day/0.3m2. The ground water is mildly alkaline with pH value 6.5 to 8.5, chloride 10 to 40 ppm, bi-carbonate 50 to 350 ppm, iron content ranges from a fraction of a ppm to 50 ppm. Total dissolved solids are low, hardness as CaCo3 50 to 300 ppm, specific conductance at 25 °C 150 to 650 mhos/cm. The yield from shallow aquifers is 1440 litres to 33750 litres/hour and for deeper aquifers ~ 1700 litres/hour at a drawdown of 13.41 m, specific capacity 21 litres/minute. The temperatures of ground water are 23°-25° C during winter, 24°-26° C during pre-monsoon and 27°- 28° C during peak monsoon. The general hydraulic gradient in the north bank is 1:800 whereas in the south bank it is 1: 300-400 The Tertiary sediments yield a range of water from 200 to 300 l.p.m whereas the yield from the Older Alluvium is 500 to 700 1.p.m. The estimated transmissibility and co-efficient of storage is of the order of ~ 800 1.p.m/ m and 8.2 x 10-3 respectively. Depths to water levels range from 5.3 to 10m below land surface (b.l.s). In the Younger or Newer Alluvium, ground water occurs both under water table and confined conditions. Depths to water levels vary from ground level to 10 m b.l.s. Depth to water ranges from 6 m b.l.s. to 2 m above land surface. The yield of the deep tubewells ranges from 2 to 4 kl/minute for a drawdown of 3 m to 6 m. The transmissibility of the aquifers varies from 69 to 1600 l.p.m/m and the storage co-fficient is of the order of 3.52 x 10-2.

Four Flint Implements

1938 ◽  
Vol 18 (3) ◽  
pp. 258-261 ◽  
Author(s):  
J. Reid Moir
Keyword(s):  
Water Table ◽  
Land Surface ◽  
Flood Plain ◽  
Deep Foundations ◽  
The South ◽  
Power Station ◽  
Suction Pump ◽  
South West

It is now some years since I first drew attention to the discovery of certain very perfect leaf-shaped blades, of Early Solutré type, at Ipswich. These specimens were found during the putting in of deep foundations for a chimney-shaft at the Ipswich Corporation's Power Station in Constantine Road. The blades, which are unabraded, came from below a considerable thickness of gravel, where, it may be supposed, there at one time existed a land surface inhabited by Early Solutré man. This land surface is now buried beneath the Flood Plain terrace of the River Gipping, and is well below the water-table of the locality. It is clear, therefore, that since Early Solutré man lived in the Gipping Valley, a marked sinking of the East Anglian area has taken place. Following the appearance of my paper upon the blades found at Constantine Road, Ipswich, other specimens which, by their forms and manner of flaking, are also referable to Early Solutré times have been recovered. These examples have come to light about a mile farther up the valley. The site is situated on the south-west of the Bramford Road where the Flood Plain gravel is being exploited by Messrs. Warren Livingstone, Ltd. The gravel is raised by means of a powerful suction-pump, and, from my observations at Bramford Road, I entertain little doubt that, as at Constantine Road, the Flood Plain Early Solutré land-surface is present there below the Flood Plain gravel.

Temür and the problem of a conqueror's legacy

1998 ◽  
Vol 8 (1) ◽  
pp. 21-41 ◽  
Author(s):  
Beatrice Forbes Manz
Keyword(s):  
Economic Stress ◽  
Islamic Culture ◽  
The South ◽  
Political Fragmentation ◽  
The North ◽  
The World ◽  
History Of

Temür has been many things to many people. He was nomad and city-builder, Turk and promoter of Persian culture, restorer of the Mongol order and warrior for the spread of Islam. One thing he was to all: a conqueror of unequalled scope, able to subdue both the vast areas of nomad power to the north and the centres of agrarian Islamic culture to the south. The history of his successors was one of increasing political fragmentation and economic stress. Yet they too won fame, as patrons over a period of brilliant cultural achievement in Persian and Turkic. Temür's career raises a number of questions. Why did he find it necessary to pile conquest upon conquest, each more ambitious than the last? Having conceived dreams of dominion, where did he get the power and money to fulfill them? When he died, what legacy did Temür leave to his successors and to the world which they tried to control? Finally, what was this world of Turk and Persian, and where did Temür and the Timurids belong within it?

Durrington Walls: a Ceremonial Enclosure of the 2nd Millennium BC

Antiquity ◽  
1968 ◽  
Vol 42 (165) ◽  
pp. 20-26 ◽  
Author(s):  
G. J. Wainwright
Keyword(s):  
Land Surface ◽  
Outer Edge ◽  
The South ◽  
Double Row ◽  
Early 19Th Century ◽  
Radiocarbon Dates ◽  
Southern Sector ◽  
The North ◽  
Animal Bones ◽  
Dry Valley

Durrington Walls lies one quarter of a mile to the north of the outskirts of Amesbury in Wiltshire and 9 miles north of Salisbury (SU 150437). Stonehenge is situated 2 miles to the south-east and 80 yds. to the south of the enclosure is Woodhenge which was excavated by Mrs Cunnington in 1926-8. The much ploughed bank, which encloses a dry valley opening on to the River Avon, was initially recorded by Sir Richard Colt Hoare in the early 19th century (1812, 169), but until the recently completed series of excavations the only digging on the site was that carried out by Professor Stuart Piggott in 1952, despite recognition of the enclosure as being one of the largest henge monuments in the country. The 1952 excavations were in the nature of an exploration on both sides of a pipe trench where it intersected with the bank in its southern sector (Stone, Piggott and Booth, 1954). A double row of post-holes was recorded along the outer edge of the bank and a quantity of animal bones, flints and sherds of Grooved Ware was found on top of the old land surface which was preserved beneath it. Sherds of Grooved Ware and two small fragments of Beaker were recorded from domestic refuse overlying the bank talus. Radiocarbon dates of 2620± 40 and 2630 ± 70 BC were obtained from charcoal under the bank in its southern sector (Piggott, 1959, 289). These determinations were described by Professor Piggott as ‘archaeologically unacceptable’ as two small scraps of Beaker pottery were found in association with the abundant Grooved Ware.

scholarly journals Global change affects differently at local scales animal populations: why Starlings still expands to the south while other temperate species go to the north?

2021 ◽  
Author(s):  
Alexandra Rodriguez ◽  
Giuseppe La Gioia ◽  
Patricia Le Quilliec ◽  
Damien Fourcy ◽  
Philippe Clergeau
Keyword(s):  
Climate Change ◽  
Global Change ◽  
Sturnus Vulgaris ◽  
European Starling ◽  
Distribution Area ◽  
The South ◽  
The North ◽  
Animal Populations ◽  
The World ◽  
Landscape Transformations

Global change, which regroups global warming, landscape transformations and other anthropic modifications of ecosystems, has effects on populations and communities and produces modifications in the expansion area of species. While some species disappear, other ones are beneficiated by the new conditions and some of them evolve in new adapted forms or leave their ancient distribution area. As climate change tends to increase the temperature in several regions of the world, some species have been seen to leave areas in equatorial regions in order to join colder areas either towards the north of the northern hemisphere or towards the south of the southern one. Many birds as have moved geographically in direction to the poles and in many cases they have anticipated their laying dates. Actually, two tit species that use to lay their eggs in a period that their fledging dates synchronize with the emerging dates of caterpillars are now evolving to reproductive in periods earlier than before the climate change. Several species are reacting like that and other ones are moving to the north in Europe for example. Nevertheless, and very curiously, European starling, Sturnus vulgaris, populations are behaving on the contrary: their laying dates are moving towards later spring and their distribution area is moving towards the south. In this study we explore and discuss about different factors that may explain this difference from other birds.

Decolonising cities of the global South in the classroom and beyond

2020 ◽  
Vol 91 (5) ◽  
pp. 535-552
Author(s):  
Astrid Wood
Keyword(s):  
Global South ◽  
Colonial Literature ◽  
The South ◽  
Post Colonial ◽  
The North ◽  
The World ◽  
North And South

In the post-colonial context, the global South has become the approved nomenclature for the non-European, non-Western parts of the world. The term promises a departure from post-colonial development geographies and from the material and discursive legacies of colonialism by ostensibly blurring the bifurcations between developed and developing, rich and poor, centre and periphery. In concept, the post-colonial literature mitigates the disparity between cities of the North and South by highlighting the achievements of elsewhere. But what happens when we try to teach this approach in the classroom? How do we locate the South without relying on concepts of otherness? And how do we communicate the importance of the South without re-creating the regional hierarchies that have dominated for far too long? This article outlines the academic arguments before turning to the opportunities and constraints associated with delivering an undergraduate module that teaches post-colonial concepts without relying on colonial constructs.

Origins

2020 ◽  
pp. 12-27
Author(s):  
Kenneth P. Miller
Keyword(s):  
Nineteenth Century ◽  
Gold Rush ◽  
The South ◽  
Origin Stories ◽  
The North ◽  
The World ◽  
Maritime Province

This chapter argues that the polarization of Texas and California can be traced to their origins. The chapter examines the two states’ common experiences as possessions of Spain and Mexico; their mid-nineteenth century American settlement, conquest, and admission as states; and their opposite positions on the questions of slavery and secession. Although the two origin stories have similarities, they also bear crucial differences. Texas’s bloody independence struggle and its decade-long career as an independent nation were different from California’s experience as a remote maritime province inundated by a global gold rush and its rapid admission to the Union. Most critically, Texas was settled by American southerners and was oriented toward the South, while California was settled by migrants from across the nation and around the world and was oriented toward the North. These differences became imprinted in the states’ identities and helped shape their futures.

Hypogenic caves in France. Speleogenesis and morphology of the cave systems

2010 ◽  
Vol 181 (4) ◽  
pp. 327-335 ◽  
Author(s):  
Philippe Audra ◽  
Jean-Claude D’antoni-Nobecourt ◽  
Jean-Yves Bigot
Keyword(s):  
Water Table ◽  
Thermal Convection ◽  
Land Surface ◽  
Meteoric Water ◽  
Thermal Conditions ◽  
Development Trend ◽  
Oxidation Potential ◽  
Bedding Planes ◽  
The World ◽  
Iron Pool

Abstract Hypogenic caves develop by recharge from below, not directly influenced by seepage from the overlying land surface. Several processes of speleogenesis are combined, involving CO2 or H2S produced at depth. If the recharge from depth remains uniform, the growth of selected fissures is prevented, giving rise to maze cave systems with an upward development trend, which is defined as “transverse speleogenesis” [Klimchouk, 2003]. Hypogenic caves are much fewer than epigenic caves (i.e. developed downwards by meteoric water with aggressivity derived from soil). In France, as in the rest of the world, hypogenic caves were poorly recognized until recently because of their lower frequency, subsequent epigenic imprint often hiding the true origin, and the absence of a global conceptual model. However, about a hundred of hypogenic caves have been identified recently in France. The extreme diversity of hypogenic cave patterns and features is due to the variety of geological and topographic settings and types of flow. Thermal caves are a sub-set of hypogenic caves. Active thermal caves are few and small (Mas d’En Caraman, Vallon du Salut). Often, thermal influences only occur as point thermal infeeders into epigenic caves (Mescla, Estramar). In addition to the higher temperature, they may be characterized by CO2 (Madeleine) or H2S degassing, by warm water flowing in ceiling channels, or by manganese deposits. The Giant Phreatic Shafts locate along regional active faultlines. They combine all characteristics (thermal, CO2, H2S), due to the fast rising of deep water. The Salins Spring has been explored by scuba diving down to −70 m. Such a hyperkarstification is responsible for the development of the deepest phreatic shafts of the world: pozzo del Merro, Italy (−392 in). Inactive hypogenic caves may be recognized by their specific mineralization or by the presence of large calcite spar. Metallic deposits are due to the rising of deep waters that are warm, aggressive, and low in oxidation potential. Mixing with meteoric water generates Mississippi Valley Type (MVT) sulfidic ores. Iron deposits as massive bodies (Lagnes) or onto microbial media (Iboussières, Malacoste) making specific facies, such as “black tubes”, iron flakes, and iron pool fingers. Other frequent minerals are Mn oxides and Pb sulfur. In such low thermal conditions, calcite deposits occur as large spar in geodes or as passage linings. Other inactive hypogenic caves may also be recognized by characteristic patterns, such as mazes. The relatively constant recharge into confined karst aquifers suppresses fissure competition, so they enlarge at similar rates, producing a maze pattern. In horizontal beds, mazes extend centrifugally around the upwelling feeder. The juxtaposition of multiple discrete vertical feeders produces extended horizontal mazes. In gently tilted structures, 2D mazes extend below aquitards, or along bedding or more porous beds (Saint-Sébastien). In thick folded limestone the rising hypogenic flow alternatively follows joints and bedding planes, producing a 3D maze cave in a staircase pattern (Pigette). Isolated chambers are large cupola-like chambers fed by thermal slots. Thermal convection of air in a CO2-rich atmosphere causes condensation-corrosion that quickly produces voids above the water table (Champignons Cave). Sulfuric acid caves with replacement gypsum are produced by H2S degassing in the cave atmosphere. H2S oxidizes to H2SO4, which corrodes the carbonate rock and replaces it with gypsum. The strongest corrosion occurs above the water table, where sulfide degassing and thermal convection produce strong condensation-corrosion. Caves develop headward from springs and from thermo-sulfuric slots upward (Chevalley-Serpents System). The low-gradient main drains record base-level positions and even the slightest stages of water-table lowering (Chat Cave). Hypogenic speleogenesis provides better understanding of the distribution of karst voids responsible for subsidence hazards and the emplacement of minerals and hydrocarbons.

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