:: Water resources- as a result of Hydrogeology ::

Water resources- as a result of Hydrogeology

Water resources development on a watershed basin requires integrating surface and subsurface data, which will permit a detailed understanding of the hydro-geologic environment and the groundwater regime. These include:

climatic records, including information on rainfall, humidity, and evaporationrates;
topographic maps which define the drainage networks, including ephemeralstreams;
hydrologic data, especially relating to seasonal variation in stream flow;
data on soil thickness, as well as the main soil types and their distribution;
distribution of rock exposures and a general overview of the depth of weathering;
the main rock types found at shallow depths;
definition of pore networks in the rocks, and all factors governing theirdistribution;
recognition of the main water recharge areas, discharge locations, andgeneral flow directions of ground water;
fluid-flow characteristics of the main aquifer types, including yield datafrom existing wells; and
maps of straight-line ground features (lineament), commonly defining fractures,which can be identified by satellite image analysis.

Various Geological formations of India

Geology of India is as diverse as its geography and people. It contains rocks covering almost the entire spectrum of the Geological Time Scale.

1) The Archean (Dharwar):- The term Archean refers to very ancient gneisses, schist and granites which constitutes the platform on which all sedimentary formation. In India they are found in abundance and cover 2/3rd of the peninsula. They are very well developed in South-India, Rajasthan, M.P, Eastern-parts of India, in the Singhbhum and Gangapura district, in Bihar, Orissa and Eastern-Ghats ranges.

2) Cuddapah Super group: - The name of this system has been derived from the Cuddapah basin of Andhra Pradesh where it has been best developed .It includes shales and Quartzite in the alternate layers. It is found in Cuddapah district in Andhra Pradesh. It is also found in Vidharbha, South-Maharashtra, Orissa, M.P, and Rajasthan.

3) Vindhyan Super group: - The Vindhyan constitutes un-metamorphosed columns of Calcareous, Arenaceous, and Argillaceous sediments .The Vindhyan rocks are developed in ‘Son-valley’ and in certain parts of Rajasthan, M.P and A.P.

4) Gondwana Super group:- The name of this formation is derived from the Gond –kingdom of M.P. The Gondwana rocks, mainly fresh water sediments are found deposited in shallow, elongated basin brought about by block faulting. The Gondwana rocks are developed in peninsular region of India and they are along the: I) Damodar and Son valley. ii) Upper Narmada and along the Godavari valley. and Iii ) along Mahanadi valley

5) Deccan Trap: - The Deccan Traps is a large igneous province located on the Deccan Plateau of west-central India and is one of the largest volcanic features on Earth. It consists of multiple layers of solidified flood basalt that together are more than 2,000 m thick and cover an area of 500,000 km The gases released in the process may have played a role in the extinction of the dinosaurs.

6) The Tertiary group: (65-1.64 million years ago). Grasses became more prominent, leading to marked changes in the dentition of plant-eating animals. With most of the dominant reptile forms having vanished at the end of the Cretaceous, the Cenozoic became the age of mammals. Thus, in the Eocene epoch, new mammal groups developed. In Miocene times, marsupials were numerous, and anthropoid (human-like) apes first appeared. Placental mammals reached their zenith, in numbers and variety of species, in the Pliocene, extending into the Quaternary period.

India these period has witnessed the igneous action on a very large scale. Tertiary rocks cover very large part of India . They are very well developed in Saurashtra in Gujarat, Orissa, and Midnapur.

Geology of other parts of India

Deccan Traps, Western India

Deccan Trap is believed to be the result of sub-aerial volcanic activity associated with continental divergence in this region of the earth during Mesozoic. The Deccan basalts may have played a role in the extinction of the dinosaurs. Most of the basalt was erupted between 65 and 60 million years ago. Gases released by the eruption may have changed the global climate and lead to the demise of the dinosaurs 65 million years ago. Continental flood basalt provinces are laterally extensive lava accumulations of substantial thickness and low topographic relief Rampino and Stothers, 1988 India’s dominantly tholeiitic Deccan Trap flood basalt province presently extends across approximately one sixth of the subcontinent, encompassing up to 106 km2 of its western portion Deshmukh, 1982. The basalts include Traps down faulted into the Arabian Sea west of Mumbai (Bombay) and forming part of the Seychelles micro-continent and possibly originally occupied a volume of up to 106 km³prior to their erosion. Mesozoic-Cenozoic Cover Major flood basalts forming the Deccan Traps in India are probably the most important in terms of climate change mitigation (McGrail, 2005).

The Mumbai and Salsette Islands

landmass comprises a linear depression bounded by easterly and westerly ridges (Sukheswala, 1956). Muddy sediments deposited in the central lowland dip 12–150 west, and lavas up to 250 west (Sheth et al., 2001a). A separate classification to the Deccan chemostratigraphy, established in the Western Ghats and now covering much of the main Deccan province (MDP), exists for the distinct geochemistries of Mumbai intrusives and extrusives (Sethna, 1999). The Amboli (Bom), Worli (Wo) and Bandra (B) intertrappean shale sections detailed here occur within the Mumbai Island Formation, the lower most of the Salsette Subgroup Worli intertrappeans occur stratigraphically above the Malabar Hill flow The thickness of shale bed is about150 m, interrupted only by a 10-m tuffaceous breccia (hyaloclastite) horizon, and a 5-m basaltic layer. The nearby Bandra tunnel also runs through this sedimentary unit, and the Amboli section possibly represents a lateral equivalent.Pandey and Agrawal (2000) detected several sedimentary basins offshore of Mumbai and in adjacent western Indian offshore areas, retaining India’s largest hydrocarbon reserves. Stratified intertrappeans in quarries around Jogeshwari have been intruded by a columnar jointed tholeiitic and are overlain by a basaltic lava flow. The position of Jogeshwari exposures within the regional stratigraphy, and possible provincial north– south correlations,

Kutch:

The Kathiawar and Kutch areas of the state of Gujarat mostly comprise of Cretaceous and Jurassic Sandstone. The kutch region has the most varied geological formations. One can encounter Sandstone-arrenaceous and argillaceous types and of different ages viz; Bhuj series Sandstone and Wadhwan Sandstone, Deccan traps as well as recent to sub-recent formations. The generalized geological succession of the entire area can be summarized as;

FORMATION APPROXIMATE GEOLOGICAL POSITION

Dwarka beds Recent to sub-recent
Millionite Limestone Higher Tertiary or post Pleistocene
Deccan Trap suite Cretaceous to Eocene
Wadhwan Sandstone Cretaceous
Umia beds Jurassic (upper Gondwana )

Geological Characteristics of Central India.

GROUP	ROCK TYPE	AGE
Alluvium		Recent
Deccan Traps	Basalt	Late Cretaceous
Gondwanas	Sandstone and Shale	Upper Carboniferous to middle
Vindhyans	Sandstones and Shale	Late Precambrian
Bijawars	Quartzite and phyllite	Early Precambrians
Archaens	Granites

Geology of Bangalore-Kolar region

Kolar district consists of immense expanse of migmatitic gneisses classified as Peninsular gneisses and the younger granites are seen as elongated NS trending patches intruding the gneisses. From the groundwater point of view, these rocks are classified as crystalline formation. The fracture/fissure system developed along with the joints and faults traversing the rocks facilitate groundwater circulation and hold moderate quantity of water. The quality of the groundwater is governed by the mineralogical composition of the rocks. The ultramafic, metavolcanic and schistose rocks are seen as scattered masses. These schistose rocks are poor aquifers and yield poor quality water in very less quantity. The joint pattern in the metavolcanic rocks control movements of water and they normally yield better quality water. Groundwater in general occurs in the water table conditions in the
weathered and decomposed mantle and also in semi confined conditions in the deeper fractures (GoK, 2002). Acute shortage of drinking water and the high fluoride content in groundwater have combined in the rise of this unique tradition.

Geology of Kanchipuram-Chennai region

Stratigraphic sequence of Upper Gondwanas is found here. It shows presence clays, shales and sandstones as its litho-units. They occur in a cyclic fashion with shales and clays having predominance.“The district is underlain by a wide range of geological formations from the consolidated fissured formations of Archaean age through semi-consolidated formations of Mesozoic and Tertiary age and unconsolidated alluvial formations of Quaternary age.” (CGWB, TN)

Hydrogeology of Solan district-H.P.

The State essentially is hilly terrain, comprising of fissured formations with a few inter montane valleys having Quaternary alluvial fill. The sub-mountainous tract is a part of piedmont alluvial plains, which merges with Indo-Gangetic alluvium towards south west. Kandi belt and the adjoining hill slopes are underlain by boulders, gravels and clay. The unconsolidated sediments, occurring in the inter-montane valleys and in the sub-montane tracts constitute the principal ground water reservoirs. The yield of the tube wells ranges 100 to 120m3/hr in valley fills. The yield of bore wells in hard rock is limited. The quality of ground water is generally good.

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