Mod-01 Lec-01 Introduction : Ground Water (GW) Utilization and Historical Background

Mod-01 Lec-01 Introduction : Ground Water (GW) Utilization and Historical Background


Ah welcome to this ahh nptel phase two course
on groundwater hydrology which is being developed by me drgr desai ahh and my colleague dramir
bandar are both from the department of engineering iit karagpur now first let us start with this
lecture number one module number one on introduction so here we will start with the the basic the
meaning of the word ground water and how it has evolved which i would like to abbreviate
as a gw so this is the ground water is the water available below the ground surface in
soil or rock pores also known it is also known as sub surface water for the simple reason
that it is available below the ground and we all know that for sustain life water is
the second most important requirement next only air and it comes even before food so
water is used for various purposes right from the drinking and cooking as well as other
purpose and the water the required for this drinking and cooking is known as fresh water
fresh water is the purest form of water used for drinking cooking the human depends on
water on fresh water water in general or fresh water in particular its starts with the rain water or else surface water else or else
ground water or else desalinated water or else other fresh water
here i would like to mention that the rain water as and when it is available okay we
know that the duration of the rain water is very limited as well as many times a spatial
extent of rainfall is also quite limited so if the rainwater is stored can be stored in
the appropriate containers before it gets polluted or contaminated with other impurities
in the atmosphere or on the ground surface okay that will serve as the best purpose because
it has under the natural process of purification through this evaporation and subsequent condensation
so and because of the spatial and temporal limitation of rainwater so our ahhh hoo the
human depends if rainwater is not available then we have to come we have to sustain our
life not only for ahhh human being so also for our flora and fauna the plants and animals
so they also need to sustain their life so there fore the depends moves one surface water
so here the kaah this water may be available in any surface water body may be a river or
a reservoir or a small size reservoir like such as tank or a pond or even a natural reservoir
like lake okay so all this are as one and it also the surface water may also be available
in the form of say this mountain ice caps next if that is also not available then obviously
the human intelligence tries to explore water by ahhh that is digging below the ground and
then getting ahhh this one hoping for most of the time succeeding and getting ground
water which is generally available in well and other subsurface structure if that is
also not available that means when rain water is not available surface water is not available
ground water is not available but the area is closed to say a kahhh sea or any other
source of marine water so then we may go for ahhh say desalinated water so this desalination
is essentially the artificial process of evaporation and then creating a ahhh as when artificially
fresh water and if that is also not available we may go for other source of water such as
ahhh fog water or even mist or any other respond any any other form of fresh water okay so
therefore and as you can see so this the ground water here it lies this it is next only to
rain water and surface water so therefore it provides the necessary that is water security
spatially and temporally and because it process this water security so it is very important
to sustain life and may times it has been proved that ahhh so this ground water extraction
has been proved to be easy and feasible technically and econo and
economically so this ground water provides the necessary
water security for ahhh fresh water in particular spatially and temporal therefore the extraction
of ground water or the rather the harnessing of the ground water is very important now
let us go to the next item of this lecture that is the the ground water utilization and
historical background so coming to this ground water utilization
i have already mentioned in introduction that how important ground water use to provide
spatio-temporal security water security and this one in this ground water utilization
so this ground water utilization is ahhh it is ahhh ahhh ahhh done in the developed as
well as developing world in the developed world as well as in developed nations as well
as developing nation so the there has been significant amount of utilization of ground
water because for the simple reason that it is providing additional water security so
now let us let me give an example of say this ahhh an example from the developing developed
world and also an example from the developing world so this is a for example in usa in nineteen
seventy five in usa there were atleast not less than ten states wherein ground water use divided total water use
was greater than fifty percent because i am using the word not at least because i got
this one the data from only for say forty five out of fifty states that is why i am
using this word and added to this there were additionally there were not less than say
nine more states nine states wherein this ground water use divided by total water use
it was ahhh between forty and fifty percent so it can say nearly say atleast twenty percent
of the no forty percent of the states in us okay depended significantly on ground water
for their ahhh for carrying out their activies various activities now and now let me provide
an example from ahhh india the recent as one say in india during two thousand four
so the ground water development that is ahhh developing stage okay that is
the ground water extracted divided by ground water available so this was more than hundred
percent in three state of punjab haryana and rajasthan of course this is not a healthy
sign but still it can realize the importance of ground water and we know that punjab and
haryana are known as the ahh the agriculture power houses in india so you can imagine the
importance of ground water in likewise so in the the national capital of territory delhi
also had a ahhh ground water stage of ground water development of for more than hundred
percent and during the same year so there were five more states that is gurajat karnataka
tamilnadu uttar pradesh and uttarakhand and where in ground water the stage of ground
water development was between fifty and hundred percent and so this was also the case lakshadweep
the union territory of lakshadweep and ofcourse i forgot to add here that is ahhh ahhh three
states of punjab and two union territories that is pondicherry diu and daman dd okay
so this is py for pondicherry and dd for diu and daman like wise so this is a between and
hundred percent the union territory of lakshadweep had as one so like as you can say so let me
present this in a tabular form so that is ahh india two thousand four that is stage
of ground water development so let me present this in scale here so this is zero this is
forty percent so this is all in percentile so this is fifty percent then this is hundred
percent so here above hundred percent we had this is we had punjab haryana rajasthan and
the national capital territory of delhi and between this fifty and this hundred percent
we had gujarat karnataka tamilnadu uttarpradesh uttarakhand and lakshadweep okay this five
states and one union territory between forth and ahhh fifty percent so there were few more
states of andhra pradesh kerala then there was a madhya pradesh maharashtra west bengal
so you can imagine the the importance of ground water utilization
so here you can see it is ahhh say is is a one two three four five and then say ahh ten
so atleast thirteen states which covering almost more than fifty percent of physical
area fifty to sixty percent of physical area of india so they developed they depended on
ground water for significant so this explains the important of the ground water utilization
in they developed world as well as developing world such as india now let us come to the
historical development of ground water and the historical background and we know that
the one of the oldest river valley civilization the indus valley civilization that time we
have been records of ground water wells ahhh that is there were essentially open where
wells used for irrigation or even municipal purpose also and also the old testament it
contains ahh number of ahhh references regarding ground water springs and wells so around the
same period in india so during the mauryan empire we know that the ashokan the mauryan
empire under emperor ashoka it extended it all the way from the present afghanistan to
so in the eastern india close to ahhh west bengal and even to assam and also there the
there were there are ahhh records of ground water well supporing irrigation and even there
were many wells were constructed so as to facilitate the travellers so the during those
days so there were not many communication facilities and so these one so there were
many ahhh this one okay they that means ahhh so this is historically this one ofcourse
i like to show you here that it is ahhh the same thing that is ahhh before moving back
to this one i would like to show you here the the so which i mentioned here the state
wise ground water resource availability utilization and all as you can see here let me i highlighted
the one which is more than hundred percent in the similarly punjab and rajasthan more
than hundred percent and hence this haryana more than hundred percent and am sorry it
is not very visible it is a because it is a two big table so like that this one okay
let me also share with you the the replenish able ground water resources
in india as you can see here in the states of punjab this haryana delhi then almost in
rajathan also this is this one so here there is significant amount of the ground water
utilization added to that that the the states of gujarat maharashtra madhya pradesh karnataka
tamil nadu and say west bengal uttar pradesh of course here it also ahhh this is an old
map of india so therefore it does not show the new states of uttarakhand which is cardout
of uttar pradesh and this chhattisgarh which is cardout of madhya pradesh and jharkhand
which is cardout from this one so as you can see here a significant area of course andhra
pradesh also so in all this states the that is the stage of ground water development is
at least forty precent so you can imagine the importance of ground water so now let
us come to that is come to that historical back ground so here during ahh indus valley
civilization there are reports of
ground water use through open wells so this is
atleast five thousand years ago similarly
so in old testament there are references to ground water springs
and wells around the same time in india so there are there are mentioned references of
reference to ground water wells supporting irrigation during
a mauriyan empire so that is fourth and third century bc so like this we can say how important
is ground water is which is realized by human beings in this one and also now let me also
bring it to you very interesting technology of horizontal wells so we are under a impression
that though this ground water wells are essentially vertical wells it is not exactly so there
are many examples of horizontal wells and these horizontal wells are supposed to or
it has been proved that this horizontal wells have even great of yield than the vertical
ground water and in this regard i would like to mention you mention to you the ahhh about
connate which are the horizontal wells which were found in which were initially developed
in say iran so this is a typical connate as you can see here in this ahhh this is a horizontal
so this is this essentially is the connate and the this the deepest well is known as
mother well and this is the water intake area so basically this is a hilly area or a mountainous
area where there is a ahh significant amount of rainfall and this mother well as a depth
of around fifty meters or less than that and there have been examples of mother well which
are even as deeps as hundred meters say one mother well as been report to be around say
two hundred and fifty meters deep also and then so here so the unlike the mountain slope
which may be very steep so this the bed slope of this connate which is essentially a horizontal
well horizontal and mild sloping well so this is the slope direction so this is the mild
slope and it reaches the ground and once it reaches ground so for the significant portion
there is a surface canal and through this surface canal the water is conveyed to the
farmlands and or irrigated land and in between the mother well and this surface canal so
there are number of this shafts okay and this is the quantity of the connate which is which
forms the horizontal well and so this number of shafts or the one which provides access
to this drilling this canal and so this canal this cannot so this cannot was a the technology
technology of drilling this connate where in this water from the aquifer was brought
in through the mild sloping ahh horizontal ahhh almost horizontal candid of the connate
in to the surface canal and then on to the farmland okay this was very much perfected
by people in iran almost three thousand years back and here so the length of the canal connate
am sorry was of the order of the say five to thirty kilometers most of the connate are
existing even now and so they there it is been reported that there are at least twenty
two thousand connate exisiting iran even now and which will supply atleast which will supply
at least thirty five percent of the entire water requirement in iran ok so here i would
like to mention here that is how important it is the ground water essentially so this
is a horizontal well at technology which was very much perfected in iran and from there
it went moved on to this morocco and this other north african continental regions and
then it moved as far as spain in europe so like this so the this the extraction of this
historically this ground water has been extracted not only through this ahhh the the vertical
wells also through the horizontal wells and now let me bring it to you so this is a the
you must have heard of the artesian well and here so in this artesian well it is basically
it was developed initially somewhere in france in a place called artois and in this cases
this place is basically a basically a pressurized well so here have the that is ahhh free water
table is somewhere here and then in this region where the ground surface is below the ahhh
the the the free water table so there the water is under pressure okay and here if we
make a if we puncture this one then the water will gush out of this artesian well and ahh
so it will we will give out ahh water in the form of natural fountain so this region where
in the ground level is below the the water table so that is known as the region of the
ahhh artesian water where there is a raised water table and so if ahhh if we puncture
this artesian aquifer so there will be huge amount of we can get a lot of water so this
artesian wells also were developed sometime in the middle of this one and added to this
is the so in the in eighteen hundred and four there was a instance of first deep tube well
which was dug in and around calcutta and so it had a depth of five hundred meters and
so this tube well ahh was the the can say is the major this one it indicates the major
milestone in ground water harnessing or development likewise in nineteen thirty six so this ganga
valley state tubal irrigation scheme so here i would like to mention so that is the so
there are at least twenty thousand connate that is horizontal
condit wells in iran even now supplying at least thirty five percent of the water requirement
of iran so you can imagine how important it is and added to that is say that is the in
eighteen hundred four the there was ground water development through a five hundred meter
deep tube well or say bore well around kolkata in india so there was a reported okay and
so in nineteen thirty six ganga valley state tubal irrigation scheme was launched in up with fifteen hundred
deep tube wells of course there are been parallel there are been many development in western
world also and so obviously came it all shows how important is the the ground water development
and here let me also show you an example of horizontal well as you can see here is an
aquifer with water table here and that is the there is a sloping slide and this aquifer
is bounded by impair case barrier and then say some rock formation here so through this
there is a this horizontal well and ofcourse the depending upon the the water table so
this we can ground water can be ahhh harnessed through this horizontal valley well so now
let us come to the that is the ground water in hydrologic cycle so here i would like to which is also known
as the water cycle and here so this is a schematic diagram and as you can see so this is the
ground surface so this is a ah surface water body such as lake or a river and so this is
the groundwater table which represents the level of the saturated ground water which
also joins the sea or ocean and here so there is a there is a evaporation from ocean surface
or land surface through air transportation as well as from the surface of surface water
bodies such as lake or river as well as through this plants and then all this evaporated water
so it gets ahhh accumulate in the clouds which are formed here and then so this clouds they
move and then so there will be a cloud condensation and then there will be a precipitation which
is which may be either solid form through snowfall or hailstorm or whatever and so this
precipitated water it will percolate through the ground surface and eventually it will
form so water known as the aquifer which have water bearing state and of course here there
is a bedrock also and the so there are also among the aquifer they are confirmed as well
as unconfined aquifers and then so there is a so this confined aquifers which are at the
deeper depths so they get their water from this deep percolation so here this is a deep
percolation and then this is the shallow or the top or the water table aquifer is also
known as unconfined aquifer ok and so now coming to this ahhh the hydrologic cycle we
know as that so quantitatively so we can represent the same thing that is hydrologic cycle so
here we can say this is so this is the clouds and here so this is the atmospheric segment
of the hydrologic cycle and then so here there is also so there is a this is a evaporation
and evaporate transportation and then here so this is a precipitation okay and then so
there is a so this is the surface runoff and then so there will be infiltration and then
so here there will be so this is the groundwater table and so here this is the the ground surface
so this is the surface water body and then here you can say this is a sea or ocean
okay so essentially so this is a cycle and in this case now let me explain you the various
quantities involved here and as you can see so this sea or ocean so
this represent almost say ninety six percent of water by volume and of course here there
are these so these are the mountain ice caps and of course here there is a also this is
a so this is the ground water in this confined and unconfined aquifers so here i would like
to see this i like to so this is the unconfined that is water table aquifer at the top and
here so this is the just schematically showing this one so this is the confined aquifer at
the bottom below that so this is the hard rock here so like this and as i was mentioning
so this sea or ocean water represents ninety six percent of the water volume so the only
remaining nearly three to four percent is the fresh water and as you can show let me
show you here and so this is the brackish or saline or other
water which represents a almost a ninety seven and half percent of the total volume of water
on the earth and only this two and half percent is the fresh water and of course this ninety
seven and half percent we cannot use it for our the ahhh to maintain the metabolic activity
of a human beings animals and plants and this two and half percent of water and is out of
this so nearly seventy percent is stored in the polar ice and glaciers and then so this
thirty percent is stored in ground water and of course very little say one fourth of a
percent are fresh water available in the surface water bodies and here at this so therefore
as soon as we can see so this polar ice or glaciers there available only in the cold
regions or cold mountains region where as ground water is available almost everywhere
the fresh ground water so and here so this fresh ground water up to say one kilometer
depth so it is a nearly half of that one and then below one kilometer depth so it is the
remaining half and then of course very small percent of that is a soil moisture so here
so this as you can see this hydrological cycle so the there is a significant amount of this
one and let me go back to you again this hydrologic cycle so although the entire water the global
water volume is of order of say around fourteen hundred million kilometer cube so out of that
so nearly ninety six say ninety six to ninety seven is brackish or salt water or marine
water so therefore so this as you can see this this ninety seven percent of water is
useless so it is only remaining two to three percent of water two and half percent of water
so out of this so one third of this is available in ground water and this ground water is available
in say almost all the regions rather than the the mountain ice caps so the mountain
ice caps are available only in the mountains region or the polar region whereas this ground
water this fresh ground water is practically available everywhere so therefore how important
it is ah to that is manage the ground water to maintain its ahhh this one supply and demand
and so that this water table so as we can see here so this water table so it should
be at the reasonable depth below the ground it should not be too deep it should not be
too shallow so if it too shallow then it may create a water logging or that is a drainage
and water logging problems and if it is too deep then this extracting of this ground water
will require lot of energy lot of costs many times these days we have the ahh this high
capacity pumps which are being used to extract a ground water like multi stage submersible
pumps and so on so their use for extracting the ground water through this wells ok so
therefore to make it technically as well as economically sustainable as well as ecologically
sustainable we need to maintain a balance between the ground water availability ground
water supply and demand so by so that we can maintain the depth of the water table healthy
depth of the water table which is neither too shallow not too deep and we can also maintain
the ahh balance between the ground water supply and this ahhh ground water demand so there
by we can provide the water security in the form of fresh ground water which is practically
available everywhere in the nearly twenty nine percent of the land surface on earth
on the other hand so this at the same time this the recent ahhh this climate change associated
impact so they are also affecting this one so that is the ahhh their affecting this one
and this climate change impacts are ahh causing the mountains caps to the polar ice as well
as glaciers of course let me also write this is a glaciers the melting of glaciers and
polar ice and so therefore it is extremely important ahhh to see that so they ahh water
which is melted because of the climate change and the global warming effect so is stored
in the form of ahhh ground water and so in the next lecture we will see the other ahhh
aspects of so this thank you

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