Development of water wells

WATER WELLS
DEVELOPMENT OF WELL

To avoid damages and failures of well, well development matters a lot. The main objectives are

1. To clear mud cake formed on bore well wall against permeable zone
2. To clear invaded permeable zone and to remove material which give problem to yield
3. To minimize the skin effect and maximize well efficiency and specific discharge (Q) of the well.

Development Methods

Following two methods does the development of wells

1. Dispersed technique in which development forces allowed to act on the entire screen length at one time

2. Concentrated method in which the force is opposed on a reduced section of the screen at one time


The general dispersed methods are over pumping backwashing, mechanical surging and air development by surging and pumping. The concentrated methods are air surging and lifting and high velocity water jetting and airlifting.

Use of Chemicals

Using chemicals for well development in another efficient process. Most commonly used chemicals are polyphosphate- act as deflocculates and dispersion agent for clays and removal of mud cake. Acids which dissolve acid soluble parts of the formation, permits higher flow rate of water in to the borehole.

Development of Hard Rock Wells

The best technique in chemical treatment followed by air surging and lifting. These are aquifer development techniques in hard rock area where acids are used. Explosives are used hydro fracturing is also most effective to the aquifer yield.

Maintenance And Rehabilitation

The major components of a well maintenance are maintenance of the well and pump for that logbook and history book should be properly maintained to respective wells.

Pump Maintenance

Following points should be taken care of in pump maintenance. If yield falls about 10-15%, pumped should be examined. Any defect in pump observed, intermediate rectification should be done. Well bottom should be clear from filling well.

Well Sickness

The general types of well sickness are,

1. Sand pumping
2. Decrease in yield
3. Deterioration of quality.

Sand pumping due to various reasons like bridging of gravels, improper design, improper selection of gravel, inadequate development high rate of pumping, rapture in screen existence of gases in aquifer zone etc so for this proper understanding of the problem and proper remedies should be taken like lowering proper screen, proper gravel size etc if the problem is due to improper selection of screen and gravel.

Decrease in Yield

In some case, after the proper development, the yield of the well will be very low this is because of the change in regional hydro-geological parameters, for example, in cretaceous growth of bacteria, erosion structural failures or interference of another well nearby. For this hydro fracturing and chemical treatment, mechanical brushing, etc., needed.

Deterioration of Quality

Due to the contamination in surface water, inadequate flushing of aquifer, growth of bacteria etc. For this prevention measures like prevention of seepage of surface contamination and promotion of sufficient recharge should be done.

Ground Water Flow Equation

When the fluid mass flows through various porous medium it will follow the physical property and nature of media. With the combination of Darcy’s law and equation of continuity, we can describe the conservation of fluid mass during flow through porous medium

CONFINED AQUIFER

Steady State Saturated Flow

Here the flow is taking place in all the three directions. Hence the rate of inflow any elemental control volume is equal to the rate of out flow elementary control volume. Hence for the steady state flow through isotropic and homogeneous medium is given by following equation

This is also called as Laplace’s equation

Transient Saturated Flow

The main principle for the flow equation is the rate of flow into any elemental control volume is equal to the time rate of change of fluid mass storage within the element



In special case of horizontal confined aquifer of thickness b, S = Ss b and T = Kb, then the above equation simplified as



UNCONFINED AQUIFER

Transient flow in unconfined aquifer

Here the flow distributions govern by the water table shape. To find a solution Dupit’s given two assumptions

Flow line are horizontal, equi potential lines are vertical
The horizontal k is equal to the slope of the free surface and is invariant with depth



Solution for Ground Water Flow Equation

To solve the flow equation either analytical or numerical methods are used. In analytical methods the actual filed conditions are so complex, it becomes to obtain solution, whereas the numerical solutions are much more versatile and with widespread availability of computer, they are much easier to use than complex analytical methods

In general numerical methods, such as the finite element method (FEM) and Integrate finite difference method (IFDM) are most commonly used.

While solving the groundwater flow equation is more real time problem, boundary condition have to be considered. Basically three-boundary condition, such as variable head boundary, constant head and no flow boundary exists.


Application

Ground water is used to understand the quantities of flow and its direction. The main application is flow net analysis, water balance study, and Ground water flow modeling planning of ground water management strategies.

ELASTICITY AND COMPRESSIBILITY OF FORMATION

Rocks possessing void space are susceptible to volume change in response to external force (load) acting on it. The compressibility of the rock is expressed in term of bulk modulus of elasticity.


E - Bulk modules kg/m2
r - Mass in metric slugs/cm2
p - Pressure in kg/m2
V - Volume in m3

The reciprocal of bulk modulus of elasticity is called compressibility


It always expressed in m2/kg. In general b is individual grain in negligible and granular rocks with high porosity are more compressible than dense rocks

Relation between b and storage coefficient

In confined aquifer, change in the pressure head reflects changes in the pressure exerted on the aquiclude and the resulting elastic change in the aquifer system. The force at contact of confining layer artesian aquifer may be expressed as

Pa = Pw + ps

Pa - Total load exerted on a unit area of aquifer
Pw - Part of total load born by the confined water
ps - Part of total load born by the structural skeleton of the aquifer

During pumping in a confined aquifer water is discharged due toe the expansion of water and compression of rock formation. Conversely when pumping stopped, the pressure head builds up gradually due to the transfer of land water itself undergoes slight contraction.

Effect of Elasticity of Confined Aquifer on Water Level in Wells

In confined aquifer, changes in external load on them is reflected as variation in water levels in the wells, which are tapping them


Atmospheric Pressure

In confined aquifer, when the increase in the atmospheric pressure produces decreases in the water level and conversely. This is expressed as Barometric efficiency, which is



The barometric efficiency is interpreted as a measure of the competence of overlying confining bed to resist pressure changes.

Tides

The responses to the tides are recorded in sinusoidal fluctuations. Contrary to the barometric effect, in the case of ocean tides, as the sea level rises, ground water also increases. Tidal efficiency C is related it the barometric efficiency B by

C = 1 – B

Earthquakes

Earthquakes shocks produce small fluctuations, hydroseisms, in well penetrating confined aquifer. The passage of seismic wave through the confined layer of aquifer resulting compression and expansion of layer. Hence fluctuations appear after little more than one hour even from the most distant earthquake centers.

External loads

Changes in loading results in Change in hydrostatic pressure in confined aquifer because of its elastic property. For example in wells located near railway lines, passing train produce measurable fluctuations of the piezometric surface.

GROUND WATER PROVINCES OF INDIA

The ground water provinces occurring in India have been classified into 8 as follows
1. The Precambrian Crystalline province
2. Precambrian Sedimentary province
3. Gondwana Sedimentary province
4. Deccan Trap province
5. Cenozoic Sedimentary province
6. Cenozoic Fault Basin province
7. Indo-Gangetic Alluvial province
8. Himalayan High Land province
Precambrian Crystalline Province
The province underlain by igneous and metamorphic rocks of Precambrian age extends from Kanyakumari in the south to Delhi in the north, these rocks are weathered up to 30 m and ground water occurs under water table conditions. Ground water occurs under semi-confined to confined condition depending upon the depth and nature of the fracture.
Ground water development is largely by open dug wells and large diameter wells. Well yielding 20 cum to 200 cum / day are common. Ground water movement is mainly along joints. Quartzites and marble devoid of primary porosity, opening is not numerous. Generally these are considered to be poor aquifers. In case of lime stone characterized by solution cavities can be expected to give higher yield.
Precambrian Sedimentary Basin
This province comprise of Limestone, Shale, Sandstone, Quartzites and local conglomerate belonging to Precambrian to early Paleozoic age. These province is found in I) Cuddapah basin ii) Raipur basin iii) Vindhyan basin iv) Western Rajasthan basin. Because of compaction and cementation process, the rocks mostly devoid of primary porosity, but the introduction of structural features, the secondary porosity developed and karstification of calcareous rocks have yielded copious supply of ground water. Weathering varies from up to 200 m. Ground water occurrence is largely limited to 150 m, Yield characters ranges from 5 to 200 cum / day for small drawdown.
Gondwana Sedimentary Province
This province occurring as disconnected patches mainly fluviatile or Locustrine sediments of sandstone, shale and with little amount of limestone. These rock formations are classified into lower and upper formations. Total thickness of the formation range from 6 to 7 km. Lower Gondwana is compact and it is devoid of water because source rock is compact shale. Upper Gondwana sediments form very good aquifers, because those are more arenaceous. Water table lies generally within 30 m. dug wells in productive sand tone yielded maximum water.
Deccan Trap Province
Deccan trap province comprising Basalt flows includes hard, massive traps, Vesicular traps, Tuffs, Breccias, Ash and Intertrappeans. Age ranging from late cretaceous to early Eocene. The flows are flat but dip of 5 o to 15 o is also seen in some places. The traps have been divided into three groups viz., upper, middle and lower Gondwana, which are 450, 1200, and 1500 m thick.
The occurrence of "red boles", which is reddish brown clayey material, water bearing causes problems during drilling. Ground water occurs under water table conditions in weathered and jointed traps. Bore well drilled in traps have given higher yield mostly trapping 2 or more flows. At places the contact between the traps and the basement rock have yielded considerable quantity of water.
Cenozoic Sedimentary Province
This province comprise of narrow coastal plains along the Kerala and Tamil Nadu coast, coastal fringes of Saurashtra and Kutch peninsula. In the east coast, the seaward dipping strata contain several artesian aquifers. This province characterized by sand stone and shale. Shale is more compact, impervious and yield little water. Where as sand stone and conglomerates are highly permeable and yield about 150 cum, example Cuddalore sand stone. In Cambay basin, the sediments of deltaic estuarine and lagoonal alternate with Marine sediments, which are generally saline. Springs are also developed in hilly tracts.
Cenozoic Fault Basin
These discrete fault basin are included viz, the Narmada, Purna and Tapti valleys. They contain quaternary valley fill deposits consisting of sand and gravel intermixed with silt and clay, affected by faults. Thickness ranging from 50m to 150m. These lenses are of sand and gravel, which form moderately, yielding aquifers.
The Ganga – Brahmaputra Alluvial Province
It is the next most extensive province covering almost northern Indian planes, after Precambrian Crystalline province, deposited in fore deep or crustal buckle; the thickness increases from south to north. The basement is hard rock under the alluvial sloping at an average of 1 o to 3o. In alluvium, ground water occurs in three-distinct physic-graphic and hydrological belts such as Bhabhar consist of talus material from the hill slope, which is highly permeable unsorted boulder, grave sand with little clay. The belt merges with Terai consisting of permeable water bearing gravel, sand, and pebble intermingle with silt and clay. The axial belt, which comprises of stratified fine gravel, silt and clay deposited by the river system.
Water table in this area is less then 10 mbgl. Wells have recorded free flow of 100 – 300 cum/hr. Ground water have been developed by dug, dug cum bore wells, casing wells and tube wells yielding up to 300 cum/hr for 6 to 109 m of drawdown.
Himalayan High Land Province
This province includes a group of highly folded and faulted sedimentary rock ranging in age from Paleozoic to Cenozoic. These sedimentary rocks are mainly comprising of limestone, sandstone and shale, and their metamorphic equivalents traversed by deep gorges and intermundane valley filled with alluvium this acts as conduits and transmits large quantities of water which recharges Ganga Bhramputra province. Whenever the alluvium is thick dug well for domestic purpose yield 100 – 200 cum/hr. with ion dissolved solid content.

Geographical Information System (GIS)

A GIS is a computer system capable of assembling, storing, manipulating and displaying geographically referenced information, i.e. data identified according to their locations. GIS suffers from a universally accepted definition and the definitions include land information system (LIS), Land and resource information system (LRIS), Urban information system (URIS), and Environmental information system (ERIS) and Cadastral information system (CAIS).

Important characteristics of GIS

GIS advances as powerful tools for integrating data from different sources, The vocabulary of GIS overlaps that of computer science and mathematics in general, and computer applications in particular, The four MS : Measurement (measure environmental parameters), Mapping (develop maps which portray characteristics of the earth), Monitoring (monitor changes in our surroundings in space and time), and Modeling (model alternative actions and processes in the environment) can be enhanced through the use of a GIS, GIS is both data base information system and a higher order map, Any tabular data including census and hydrogeologic data can be converted to map-like form in a GIS, GIS is a computerized map making.

Components of GIS

A geographical information system has the components- computer hardware, software, geographic data, skilled people, and display layers of spatial data.

Computer Hardware

The computer has a hard disk drive for storing data and programs but extra storage can be done by a net work, digital tape cassettes, optical CD-ROMs etc. A digitizer as scanner is used to convert maps and documents into digital form and that can be used by the computer programs. A plotter or printer is used to present the results of the data processing.

Software

The five functional groups for a GIS software and these are data input and verification, data storage and database management, data output and presentation, data transformation and interaction with the user (Burrough, 1998). Software helps in storage, analysis, and display geographic information.

Data

Data is one of the important components of GIS and it may primary or secondary. A GIS integrates spatial data with other data and can even use as a data base management system (DBMS).
(i) General Reference Maps: World, country and state, district and village maps,
(ii) Base Maps- Include boundaries of rivers and lake, parks and landmarks, place names, street and highways and raster maps,
(iii) Demographic data includes data on general population, age, education employment, and households, housing units, income by family and households,
(iv) Physical data includes data on flood plain, land use, municipal data base and road business maps and data includes data on consumer,
(v) Environmental map and data: Include data related to the environment, weather elements, satellite imagery, topography, and natural resources, and
(vi) Business Maps and data: Includes data on consumer products, real estate, telecommunications, and commercial business establishments, financial services and transportation networks.

Skilled people

Technical specialists are needed for the effective working of GIS. The GIS technology is meaningless without the skilled people who can well manage the GIS technology.
Display layers of spatial data
All of the information would be layered and displayed with each type of information being represented in a different colour. The colour allows user to easily distinguish between different types of data information from any of the data bases can be overlaid on one map. A GIS can combine many map types and display them in three-dimensional perspective views that convey information more effectively than two dimensional maps.

Working of GIS

The working of a GIS includes six stages and these include
(i) Relating information from different sources,
(ii) Data capture,
(iii) Data integration,
(iv) Projection and registration,
(v) Data structure, and
(vi) Data modeling.

Relating information from different sources

A GIS relates information from different sources in the form of thematic layers and the primary requirement for the source data is that locations which may be annotated by X, Y and Z coordinates of longitude, latitude, and elevation or national grid coordinates.

A vector model

Here information on points, lines and polygons are represented and stored as a collection of X, Y coordinates. A point feature like an observation well can be represented by a single X and Y coordinate, a linear features like roads and drainages, a collection of point co-ordinates of X and Y and Polygonal features such as sub-basins of a river basin (e.g. in the present study four order sub-basins) as a closed loop of X and Y coordinates. The vector models are useful for describing discrete features and vector data files can approximate the appearance of hand drafted maps.

A raster model

It is a collection of grid cells like a scanned map or picture. Like vector model raster model is also used for storing geographic data. Raster data files can be manipulated quickly by the computer but less detailed and less visually appealing than vector data files.

Data capture

Data capture is the process of putting the information into the GIS system and is a time consuming component of GIS work. A GIS can use an information only that in digital form, in a form the computer can recognize. Thus maps can be digitized, or hand traced with at computer mouse, to collect coordinates of features. Electronic scanning devices are also used to convert map lines and points to digits.

Editing of information is very difficult. Electronic scanner records blemishes on maps as faithfully as they record the map features. A fleck of dirt connecting two lines should not be connected. The extraneous data to be edited or removed from the digital data. Editing of information is also a time consuming one. During the process of segment checking, dead and correction, self-overlap and intersections of segments are also to be removed and this needs patience of the skilled person involved is also necessary. In the present study, the land use / land cover map editing took days for dead end, self overlap and intersection corrections.

Data Integration

A GIS can line or integrate information difficult to associate through other means. Thus we can say that a GIS can use combinations of mapped variables to build and analyze new variable.

Projection and registration

The fourth phase of a GIS work is projection and registration. A digital data can be analysed only if the data may have undergone projection, and thus integrate them (digital) data into a GIS. Projection is a basis component of cartography and is a mathematical means of transferring information from the earth’s three-dimensional curved surface to a two dimensional medium paper or computer screen. Different projections are utilized for different types of maps because each projection is particularly appropriate to certain uses.

Data structure

A GIS has the ability to convert data from one structure to another. That is from raster data file (Raster data file consists of row of uniform cells coded according to data values) to vector data file. For example, during data restructuring, a GIS can convert a satellite image map to a vector structure by generating lines around all cells.

Data Modeling

A GIS can represent two and three dimensional characteristics of the earth’s surface, sub-surface and atmosphere from information points in the form of maps. A GIS can very quickly generate maps with lines, for example if GIS makes a map from rainfall amounts, such a map may be a rainfall contour map. A contour map created from surface modeling of rainfall point measurements may be overlained and analyzed with little difficulty with any other map in a GIS covering the same area.

2.3 Applications of GIS

The important applications of GIS include
a. Disaster monitoring,
b. Sea level monitoring,
c. In the field of defence ways to win war
d. Land Use category changes, crop rotation and their impact in environment,
e. Impact analysis. For example, impact of Methyl Iso Cyanate (MIC) released from Union Carbide during Bhopal tragedy,
f. Study the spread of diseases,
g. Selection of gardens,
h. Map making,
i. Emergency response planning,
j. Simulating environmental effects.

2.4 GIS in India

When we compare the development of GIS techniques in India with that of other developed and developing countries, it has not gained any momentum. In India GIS is still in infant stage. The basic reasons may include difficulty to develop software and hardware, lack of well trained persons, won’t get reliable data on many places, for example Lakshadweep and most of the R&D institutions rare hesitant to provide data.

MORPHOMETRIC STUDY OF RIVER BASINS

River characteristics are reasonably understood by the morphometric analysis of that particular river basin. The morphometric studies on river basins were first introduced by Horton in 1932 and the study of geometry of landform and the various morphometric parameters are discussed below
Drainage basin, drainage divide, and drainage pattern -The entire area of a river basin whose runoff drains into the river basin is considered as a hydrologic unit and is called a drainage basin (Pradeep Kumar, 1999). The boundary line along a topographic ridge separating two adjacent drainage basins is called drainage divide (Upendran, 1999). Drainage pattern or drainage arrangement refers to the particular plan or design, which individual stream courses collectively form, and is influenced by factors like initial slope, inequalities in rock hardness, structural control, recent geologic and geomorphic history of the drainage basin (Leopold et al, 1964).

Stream order- First order streams are those that do not have any tributary. The smallest recognizable channels (streams) are called first order and these channels normally flow during wet weather (Chow et al, 1988). A second order stream forms when two first order streams join and a third order when two second order streams are joined and so on (Strahler, 1964). Where a channel of lower order joins a channel of higher order, channel downstream retains higher of the two orders and order of river basin is order of the stream draining its outlet, highest stream order in the basin (Chow et al, 1988).

Stream Number- The order wise total number of stream segments is known as the stream number.

Stream length- Horton’s law of stream lengths states that mean lengths of stream segments of each of the successive orders of a basin tend to approximate a direct geometric sequence in which the first order term is the average length of segments of the first order (Horton, 1945). The longer stream length indicates slower the appearance of flood and larger surface flow.

Mean stream length (Lu)- The mean stream length (Lu) is a dimensional property, revealing the characteristic size of the components of a drainage network and it contributes basin surface (Strahler, 1964). Mean stream length, Lu = å L / Nu, where åL is the total length of the stream of particular order and Nu is the number of stream segment of that order. In general Lu increases as the order of segment increases.

Drainage density (Dd)- Drainage density (Dd) is the total length of the streams in a given drainage basin divided by the area of drainage basin (Horton, 1932, 1945). Dd = åL / A, where åL is the total length of the stream and A is the area of drainage basin. Difference in Dd is due to rock type variation, run off intensity, rainfall variation, soil type, relief, initial resistivity of the terrain to erosion infiltration rate and the total drainage area of the basin.

Stream frequency (Df)- The stream frequency is defined as the number of stream segments per unit area (Horton, 1932, 1945). Stream frequency (Df) is determined by dividing the total number of streams in a basin by area of drainage basin. Thus Df=åN/A, where N is number of stream segments and A denotes drainage area.

Stream length ratio (RL)- Stream length ratio is the ratio of mean length of streams of one order to that of the next lower order, which tends to be constant throughout the successive orders of a watershed (Horton, 1945). The stream length ratio RL is given by the equation, RL = L u / Lu-1; where Lu is mean stream length of order u and Lu-1 is the mean stream length of next lower order. The larger RL values indicate more lower order sources for the next higher order streams and lower values indicate the limited length of lower order drainages to serve as hydrological sources (Kumaraswamy and Sivagnanam, 1998) and low values of RL indicate the lesser number of lower order Hortonian streams.

Relief ratio (Rh)- The elevation between highest and lowest points in a basin is called basin relief. Relief ratio indicates the overall steepness of drainage basin and is an indication of intensity of degradation processes operating on slopes of the basin and is the ratio between the total relief of the basin and its longest dimension parallel to the principal drainage line. Rh = H / Lh; where H is the total relief and Lh is the basin length.

Elongation ratio (E)- Elongation ratio is defined as the ratio of the diameter of a circle having the same area as the basin and maximum basin length (Schumm, 1956). It is a measure of shape of river basin and the value ranges between 0.6 and 1(Chow, 1964). Lower the E value, more elongated shape for the basins (Srivastava, 1978). Value ranges from 0.6 to 0.8 are regions of high relief. By analyzing elongation ratio, we can predict shape of basins. Basins with elongation ratio values above 0.9 are circular in shape, between 0.8 and 0.9 are oval shaped, 0.7 and 0.8 are less elongated and below 0.7 are elongated. A circular basin is more efficient in the discharge of runoff than an elongated basin and is significant in flood forecasting (Singh and Singh, 1997) besides concentration time is less in circular basins (Upendran et al, 1998).

Bifurcation ratio (Rb)- It is defined as the number of segments in an order to the number of segments in the next higher order (Horton, 1945). It is represented by the equation Rb = Nu / Nu+1; where Rb is the bifurcation ratio, Nu is the number of segments in an order u and Nu+1 is the number of segments in the next higher order. The bifurcation ratio ranges between 3 and 5.0 for watersheds in which geometrical structures do not distort drainage pattern (Chow et al, 1988). Theoretical minimum value of 2.0 is rarely approached under natural conditions. It is a dimensionless ratio, as drainage systems in homogeneous materials tend to display geometrical similarity, the ratio shows only a small variation from region to region. If within a net, bifurcation ratios are equal, it is called Hotron’s net.

Form factor (F)- It is the ratio of basin area to the square of basin length (Horton, 1932) and is calculated by F = A / Lb2; where A is drainage area and Lb is length of the river basin. Highly elongated basins with F value of zero and circular basin with one. Basins with high F values have high peak flows for shorter duration where as elongated basins with low F value will have a flatter peak flow for longer duration and flood flows of elongated basins are easier to manage (Nautiyal, 1994).

Circularity ratio (C)- It is the ratio of area of river basin to area of a circle having the same perimeter as basin (Miller, 1953). Like form factor, it is also a dimensionless ratio to express outline of drainage basin (Strahler, 1964) and C values are influenced by length and number of streams, geological structures, land use / land cover, climate, relief and slope of the basin (Singh and Singh, 1997).

Sinuosity index (S)- It is the ratio of channel length and river valley length (Muller, 1968). Sinuosity index reveals the topographic and hydraulic conditions of streamlines.

LAKSHADWEEP ISLANDS, INDIA

The Lakshadweep Islands are the only coral reef islands in India with rich flora and fauna, are the result of gradual assimilation of calcium from the water by corals and their turning into reefs. The islands are noted for great tourist destination for Water sports, fishing and virgin, fragile eco system. The tiniest Union Territory of India, Lakshadweep is an archipelago consisting of 12 atolls, three reefs and five submerged banks. It is a uni-district Union Territory with an area of 32 Sq.Kms and is comprised of ten inhabited islands, 17 uninhabited islands attached islets, four newly formed islets and 5 submerged reefs. The inhabited islands are Kavaratti, Agatti, Amini, Kadmat, Kiltan, Chetlat, Bitra, Andrott, Kalpeni and Minicoy. Bitra is the smallest of all having only a population of 225 persons (Census 1991). The uninhabited island Bangaram has been enumerated during 1991 census operation and has a population of 61 persons.

It is located between 8 º- 12 º 13" North latitude and 71º -74º East longitude, 220 to 440 Kms. away from the coastal city of Kochi in Kerala, in the emerald Arabian sea. Considering its lagoon area of about 4,200 Sq.kms, 20,000 Sq.kms of territorial waters and about 4 lakhs Sq.kms. of economic zone, Lakshadweep is a large territory.

The islands look like emeralds in the vast expanse of blue sea. Varying hues of turquoise blue translucent water surround them. Coral atolls, the matchless marine environment with myriad colors resulting in complex interaction of animate and inanimate things. Built on ancient volcanic formations are the Lakshadweep (meaning a hundred thousand islands), the tiniest Union Territory of India. The atolls poised on submarine banks, harbor 36 islands. Kavaratti is the Administrative Headquarter of the Union Territory.

Each island is fringed by snow-white coral sands, are marked by a huge, shallow, calm lagoon on one side which separate it from incoming swells of the outer sea by the fort wall-reef made of massive coral boulders and live corals.