Hello everyone and welcome to the 19th lecture of this introduction to remote sensing course
So far we have covered all theoretical aspects of basics of remote sensing and this is we
are going to discuss in this one one particular application which is related with groundwater
and some applications of GIS we will discuss Say integrated application of remote sensing
in GIS in groundwater studies As you know that groundwater is very important resource
for drinking irrigation and other purposes and therefore it will it remains a very important
aspect for exploration and management.
If you see that out of the total global water which is available the freshwater resources
are just 2.5 rest goes in oceans or saline water and within this (shref) fresh water
you see the glaciers and icecaps which occupies about 69% of the water and groundwater is
just roughly 31 30.1% and other water which is on the surface is 1.2 So if we go for this
then this is very tiny amount of out of what you see here out of 2.5% only this much of
30% of 2.5% is a our groundwater So replenishment of groundwater management of groundwater is
very very important and from that point of view we are going to discuss this particular
application
You can also see as a total thing that groundwater river waters and other are very very tiny
in as compared to the seawater or saline water
If we see in in Indians for Indian terms what we find that 54% of India faces high to extremely
high water stresses especially during 3-4 months of summer and except may be in the
northeast India somewhat little in J&K and rest of the places we really see a lot of
problem about the water so therefore (re) replenishment that means in simple words we
can say recharge of groundwater is very much required and also one can notice that 54%
of India’s total groundwater wells are decreasing that means the the water table is going down
in almost in all parts of India so that is another concern
Can remote sensing and GIS play a major role can we do something employing these technologies?
Especially remote sensing so this discussion is mainly on this Also if you see that the
average rainfall over India is (la) about 1120 millimeter per year so from rainfall
point of view in some way it is quite sufficient and only very tiny percentage of this rainfall
that is roughly 1% of total rainfall is sufficient for India to meet country’s domestic requirement
of water so we require a very amount of water to (re) to store in groundwater if possible
out of this 1120 millimeter to have sufficient water for the country
So therefore the groundwater recharge is perhaps the best solution which is available and total
average of annual precipitation over India is a if we calculate the total volume of water
which is falling over India is 4000 cubic kilometer which is a quite good amount of
water available and whereas in case of groundwater recharge it is just 433 cubic kilometer that
much is the groundwater recharge is happening If we double this by some means by groundwater
(re) better management groundwater recharge etc then we can solve this problem very easily
Surface water runoff is major concern which goes large amount of water there
I am going to take a very example from hard rock terrain from central India where mainly
2 types of rocks are there and you are having weathered basalt or in the basement you are
having Bundelkhand granite that is granitic rock and on in some places you are having
the basaltic rock So in this terrain in this part of the country where water is the big
problem and you see that how these small small groundwater recharge structures in form of
dams (surf) storing first the surface and then it is going to recharge the groundwater
you will see this is a part of Madhya Pradesh where this study I am going to show you
Now what how we (sa) employ a remote sensing that’s the main focus of this discussion
today that is that how best we can employ remote sensing to solve this groundwater recharge
problem So what we see here that this is a false color composite of IRS Liss 3 image
and you know is that in false color composite the vegetation will appear as red and water
bodies depending on the depth or turbidity and these will appear either black or blue
In this case there are 3 water bodies one can see one this one is the black means if
I since we have the ground information and know that there is no turbidity in these water
bodies therefore I can say that this is having quite a good depth of water in this particular
reservoir whereas as compared to this this has a shallow and therefore the bottom of
the reservoir is reflecting and instead of getting black in false color composite we
are getting blue color And there is a third one very tiny one here also which is another
small reservoir
Now what interesting feature which we are observing that this is the reservoir and downstream
of this reservoir we are seeing the growth of vegetation Similarly this reservoir and
again downstream of this reservoir we are seeing the growth of vegetation and the even
in tiny reservoir is also having in downstream growth of vegetation So that means wherever
you are having reservoirs in the downstream you are having growth of vegetation and these
are mainly agricultural fields because this image of end of February and in (thi) in this
part which where geologically it is almost same as these areas
And this is the area where you are having unweathered or weathered basalt in the basement
you are having granite and here you are having unweathered basalt and this is little higher
ground which I will show you through a digital elevation model as well So what we observe
here that since there are no reservoirs (hen) and hence we are not seeing much growth of
vegetation So wherever there is groundwater recharge structure in the downstream we are
having vegetation so this is how we start interpreting satellite images for a particular
purpose Here the purpose is to think that how the the such information which we are
interpreting or inferences we can make for groundwater recharge
And now in order to confirm all these things we this is again that area and geology another
part of earth is shown here So this in order to confirm that we are on the higher ground
or lower ground and in background you are seeing a digital elevation model and brighter
the areas higher the ground darker the areas lower the ground and over that we are having
a drainage network and what we observe that wherever this reservoir this is on though
it is on the lower grounds whereas this reservoir though it is small but on higher grounds so
after having this and this is also on the (re) relatively higher grounds as compared
to this Sironj reservoir
So if I go back to the original image where we started this discussion what we find that
the reservoir which is on the lower (grou) and higher grounds though it is small but
having a high recharge area or high benefit area large benefit area whereas this reservoir
though it is larger but it is on the lower ground as we have confirmed through digital
elevation model and it is having relatively less benefit area as compared to this one
Even the tiny one is also there so what we can think now that this is what we we can
say that this is my submerged area and this is the benefit area Similarly here the reservoir
part is my submerged and this is my benefit area Since there are no submerged area and
hence the recharge is also not much there and we don’t see (sun) such a distinct benefit
areas in this part
Now this can also be (cov) confirmed employing again digital elevation model and top of that
the satellite image has been dragged so you can see that this reservoir Sironj reservior
is on higher ground and having a larger benefit area Naren reservoir on relatively on lower
grounds and having less benefit area and this clearly indicates that though this reservoir
is small but because of higher hydraulic gradient it is providing much better groundwater recharge
as compared to Naren reservoir in this terrain
Based on this inferences and incorporating other information like geology soil geomorphology
and growth of vegetation we can employing GIS we can we can have a groundwater prospective
zone map like this which we are seeing here and so that we can indicate very clearly that
which are the good areas moderate areas poor and very poor for finding groundwater So the
valley zones specially and the though they are shown in red colors but they are the good
areas and the this violet color one are the very poor area which are very higher grounds
as well
Similarly we can also develop a potential zone for future reservoir sites That means
if I want to learning that a reservoir which is on little higher ground though may be small
can have a larger benefit area therefore if we would are looking for some solutions for
this entire area then these are the areas which are black areas which are the most suitable
to construct reservoir or groundwater recharge structures particularly in this part of the
country
If we remain almost in the same area but in instead of this interface of granite Bundelkhand
granite and Deccan traps or basaltic terrain if we focus mainly on the granitic terrain
what we find here very interesting features are there which are again natural or geological
features which are we are seeing a quartz reefs which are basically because of weathering
and erosional processes and these have these are made of quartz and they remain there and
whereas the granite which was surrounding has got weathered and got lower ground
So these these (qa) quartz reefs are serving as a barriers for groundwater flow and a same
time also these quartz reefs have been in past exploited wherever we had some stream
which was passing through these quartz reefs so that they blocked these quartz reefs and
made certain reservoirs and what you you are observing here that (the) these quartz reefs
are serving as a groundwater recharge structures and this is again false color composite so
what you are seeing there is a reservoir because of this is quartz reef is working as a dam
natural dam axis
This was blocked a stream was blocked so this is the upstream area this is the downstream
area and you are seeing a groundwater recharge and therefore growth of vegetation Similarly
here again a stream was blocked by this using this quartz reef and this is the benefit and
likewise wherever these streams which were breaching the quartz reefs have been blocked
a groundwater recharge structure have been created and what you are seeing the benefits
in form of growth of vegetation and wherever you don’t have any groundwater recharge
structures like in this area or this area you don’t see much growth of vegetation
So that clearly indicates that if you recall that 1120 millimeter of rainfall is happening
hardly 1% of rainfall is being stored as a groundwater Rest is going as a surface run
off By such means or by such structures a natural dam axis has already been there existing
so if we employ these remote sensing find out the suitable sites may also employ GIS
and we can find out the suitable sites where such a structures can be made and more groundwater
recharge can happen
So this we will see in little more detail there are 2 twin reservoirs Jhaloni and Burera
and again here you are seeing that this is quartz reef this is the downstream area this
is the upstream areas and there is a submergent area there is a benefit area Similarly here
and in a Jakhaura reservoir also sometimes what we (fin) we have found that these quartz
reefs are so strong that they do not allow much water to go through That means they are
(wo) working as complete groundwater flow variant it doesn’t matter even then because
of rainfall if by some means if we hold the water for some time it will recharge laterally
or in the surroundings of the reservoir and ultimate aim is to just ground to recharge
groundwater regime whether it is in the surrounding laterally or downstream it doesn’t matter
much
Similarly there are another reservoir and another reservoir is there which is Govind
Sagar little larger one here so this is the reservoir at the downstream you are having
Lalitpur town so when when this reservoir is full you are having a quite growth of good
growth of vegetation in the downstream in the agricultural fields and other when you
don’t have much water he problem comes
What another important thing in this part of the country if you see here this is a from
Google Earth you say natural color more or less natural color or true color image What
you are seeing the vegetation is appearing as a green and a water body as a black what
you see that this reservoir relative to the town Lalitpur town is very big so if I roughly
I say that a you know this is double the size of the town and even then the entire water
supply to town is through this reservoir either directly through pipelines or through groundwater
recharge so if in this type of terrain if 1 (bla) 1 town has to sustain and should get
the water throughout the year then at least more than double the size of reservoir is
required to (propy) to provide the water for such a town in such terrain
Why more than double because few months at least 3 to 2 to 3 months this town every year
also suffers from water (scate) a scarcity during the summer months So therefore even
a larger reservoir if it would have or the height can raised then probably we can have
water supply throughout the year so this is the terrain condition that if we want to provide
the water we have to submerge more than double the size of a town in this part of in such
terrain so that the (wat) water can go as a groundwater recharge or can be supplied
through this thing This is all this reservoir though is also having some canal network as
well
There are some examples like in around Alava and other places wherever you are seeing the
seeing the reservoir in the downstream you are seeing growth of vegetation wherever you
don’t have much reservoir you don’t see such growth of vegetation
So if we want to quantify this thing and use this in inferences or knowledge which have
developed through the interpretation of satellite images then the what we can do that we can
through this schematic we can understand that if it is submerged area which is the reservoir
area then this is the benefit area by we we that area we can identify verily easily in
false color composite by demarking the growth of vegetation whether it’s a natural or
manmade means agricultural land it doesn’t matter So by this we can identify that this
is submerged area and this is the benefit area so if we develop a ratio a index saying
that the benefit versus submerged then what scenario we see
So doing this exercise for this Bundelkhand region a part of Bundelkhand region what we
have found that there are reservoirs which are having a very large ratio that means the
submerged area is very small benefit area is very large and in the same terrain and
there are areas where you are having this ratio is 0.666 whereas this ratio is 28 So
what it what basically indicating that in such areas this is these are the areas which
are best suitable initially in the first phase or on a priority basis these are the areas
which are best suitable for groundwater recharge that means if I if I am going to submerge
a 1 square kilometer of area then in at least in 28 square kilometer area especially in
the downstream I am going to have benefit by groundwater recharge and ultimately through
growth of vegetation whereas in this area these are not that means my investment is
more and benefit I am getting less
Here the my investment is 20 square kilometer my benefit is only 14 square kilometer so
in that way it is not good but if these are the area say here upto 10 times I am getting
benefit so these are the areas where if somebody is really looking for the site to ground for
groundwater recharge then wherever these these areas these reservoirs are existing these
are the benefit areas these are the best areas where maximum benefit can be taken in specially
where this Chanderi Jakhora Padma Sagar all these reservoirs are there 28 times benefit
you submerge only 1 square kilometer of area say for example you are going to have 28 square
kilometer benefit area So by this analysis we can you know estimate or predict what going
to we have what going to happen for benefit area in this part of the country or in such
kind of terrain
One other how quickly so this is 1 question that what how much area will get benefit how
quickly the area will get benefit and this is a time series data which is very interesting
This is from Modis it’s covering a large area this is a very large reservoir multipurpose
reservoir it is it is having hydropower it is having canal irrigation it is having lift
irrigation but we are not looking from those point of view we are mainly looking from the
(gro) submerged area and benefit area from in from groundwater recharge and growth vegetation
growth
And what we observed here that when this reservoir was under construction or just filling started
you don’t see much growth of vegetation this is true color image and in just after
1 year what you start seeing growth of vegetation in that downstream area and in the mainly
in the alluvial fill areas where you had the streams or older rivers and so on and this
benefit has started coming further in 2003 a large area got green here and see what happened
in 2004 One may think that this might be the first one might be a pre monsoon image and
this might be the post monsoon image but this is not correct
If we see for the same date of all different years 2002 04 05 and 13 and what we find that
se the reservoir has started filling in 2001 and the benefits see start coming in all around
because it is having lift irrigation system as well so across the Watersat also the benefits
are coming and entire area got benefit because of this reservoir so (hydro) (pa) apart from
hydropower and other things the groundwater recharge has become the major and because
here the irrigation network and other things are there and therefore you compare and there
is a a large vegetation growth in form of agriculture land is happening
And that you can see here also that in 1990 this was the Landsat MSS image and this is
Landsat ETM image both are in in near true color and see this when there were no reservoir
the greenery was not there When the reservoir is there see in the downstream area you are
having these are all agricultural fields these is of course the forest but these are all
agricultural fields so the difference you can see how a reservoir can provide and it
is providing a quite good benefit area
This is the benefit in area where earlier before reservoir you didn’t have the water
Now in front of their house (the) you are seeing the water these are the unlined canal
network and the advantage of this that they are this water is recharging groundwater regime
and therefore you are seeing benefit of a groundwater recharge through growth of vegetation
in a large area in the downstream area
So if we start looking the entire region this is all entire Bundelkhand region and which
is all granitic terrain there are small and large reservoirs 2 reservoirs on Betwa Rajghat
and Matatila and there are other small reservoirs and what you will observe when you will zoom
these images that wherever reservoir in the surrounding or especially in downstream you
will see growth of vegetation otherwise it is implement right except in your so you are
having gradients the geological setup I have already indicated and this area suffers every
year for water scarcity so acute water (ac) scarcity but same time as earlier also mentioned
that this area is having (lotch) lot of quartz reefs which are running northeast and southwest
Some of the quartz reefs are running for 10s and 20 or 100s of kilometers and at places
they are breaching these quartz or at places the natural drainages breaching these quartz
reefs and these are the areas which can be identified based on the remote sensing data
and then reservoirs can be constructed specially for groundwater recharge point of view This
is just rose diagram to indicate that what is the orientation of these quartz reefs
So if it’s going the ground (wat) this is what we observed this quartz are like this
a stream is just passing through so that means these are these (be) these quartz reefs can
be treated as a natural dam axis and if we block this this much this much then this can
serve as a reservoir or a ground water recharge structure this is how you see from the top
and the Google Earth images these are how you see on the ground and this is this is
basically the idea that if the ground is having this kind of thing the quartz reefs like this
which you are seeing on the ground if you fill with that then it is going to recharge
the groundwater regime If a quartz reef a completely a and it doesn’t allow water
to flow through doesn’t matter even in the vicinity or in the surrounding or laterally
it will recharge the groundwater regime
So by identifying these things and and learning from developing knowledge from interpreting
satellite images and like digital elevation model or shaded relief model we and drainage
network we can identify such thing
As in this particular example a quartz reef was identified where a natural drainage was
breaching and unchecked so that day if we go for a reservoir here what happens and how
high what should be the height of the reservoir and things these things can be simulated into
GIS as I am going to explain
So this quartz relief was identified where natural drainage was breaching it and if we
feel this reservoir to the roughly the same height as currently the quartz reefs are there
then this is what the submerged area you are going to have This is purely a modeling and
if you recall the definition of GIS when I was discussing the (integra) integration of
remote sensing GIS and GPS in the definition of GIS this says that to model and display
according to user defined specification so this is nothing but the modeling
We are predicting that if the reservoir is created in the upstream this is the inundated
area going to be so you see the plan view as well as you can (cal) calculate or estimate
the volume as well how much water you will hold and you can simulate you can do the modeling
so that you can raise the you can raise the reservoir height or you can lower the height
as per our requirements and this is how in the profile along the quartz reef it will
look like this and this is the ground this is how on the ground it looks and the stream
which is still unchecked is going through this quartz reefs So this is how one can exploit
all these 2s which are available remote sensing and GIS specially and can think how to recharge
groundwater regime
And if we employ further on this then we can also know that what is basically what kind
of land use we are going to going to submerge if we construct a reservoir and that can also
be you know though before deciding the height of the reservoir So in this scenario what
what is the analysis saying that if we keep the dam axis this much this is the inundated
area 4.4 perimeter is going to be like this water level is going to be like this and dam
height is roughly 10 to 12 meter and a storage capacity is going to be in of this much quantity
and these are the land use which will submerge
So if everything is acceptable then one can go and and develop a ground water recharge
structure and benefits as you have seen will start coming within 1 or 2 years time in this
part of terrain as we have seen through the time series data of a reservoir Rajghat reservoir
in the same part of the country or in a similar terrain conditions
So what are the possibilities of employing remote sensing and GIS for groundwater especially
groundwater recharge and overall groundwater management is that we can identify suitable
sites for water harvesting based on our satellite images and (sub) supplementing that through
the like digital elevation model and others and then we can make the preliminary assessments
of impacts of reservoir even before the construction
That means we can model that we can we can try to answer those questions like how much
will be the submerged area What will what is going to be the total volume of water available
as a surface water and in which area which area we will get benefit and when which we
will seeing benefits through the growth of vegetation and how much time it will take
to see the benefit so all these answers all the questions to all these answers to all
questions can be given with such analysis And simple solutions are possible with the
local people and local material to solve this groundwater issue and water supply throughout
the year
So this this is how the remote sensing and GIS can play very important role to not only
identify the problem but also the solution solution and that simple solutions with the
help of local people and local material so this basically end to this brief discussion
on how remote sensing and GIS specially related with groundwater can be applied Thank you
very much