 Welcome to this NPTEL phase two course on groundwater hydrology, which is being developed by me, Dr. V. R. Desai and my colleague Dr. Anir Bandhar, both from the department of civil engineering IIT Kharagpur. First, let us start with this lecture number one in module number one on introduction. So, here we will start with the basic, the meaning of the word ground water and how it has evolved, which I would like to abbreviate as G W. So, this is the ground water is the water available below the ground surface in soil or rock pores also known as, it is also known as subsurface for the simple reason that it is available below the ground. And we all know that for to sustain life water is the second most important requirement next only to air and it comes even before the food. So, water is used for various purposes right from the drinking and cooking as well as other purposes and the water 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 dependence on water on fresh water, water in general and fresh water in particular, it 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 and we know that the duration of rainfall is very limited as well as many times a special extent of rainfall is also quite limited. So, if the rain water 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. That will serve as the best purpose because it has undergone the natural process of purification through this evaporation and subsequent condensation. So and because of the spatial and temporal limitation of rain water, so our the human dependence if rain water is not available then we have to sustain our life not only for this human being. So, you are also for our flora and fauna, the plants and animals, so they also need to sustain their life. So, therefore the dependence moves on to surface water. So, here the 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 a tank or a pond or even a natural reservoir like a lake. So, all these 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 that is digging below the ground and then getting this one hoping for and most of the time succeeding in getting ground water which is generally available in wells and other subsurface structures. 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 close to say a sea or any other source of large source of marine water. So, then we may go for say desalinated water, so this desalination is essentially the artificial process of evaporation and then creating as one artificially fresh water. And if that is also not available we may go for other sources of water such as fog water or even mist or any other form of fresh water. So, therefore and as you can see so this ground water here it lies it is next only to rain water and surface water. So, therefore it provides a necessary that is water security spatially and temporally and because it provides this water security so it is very important to sustain life. And many times it has been proved that so this ground water extraction has been proved to easy and feasible technically and economically. So, this ground water provides the necessary water security for fresh water in particular spatially and temporally. Therefore, the extraction of ground water or rather the harnessing of ground water is very important. Now, let us go to the next item of this lecture that is the ground water utilization and historical background. So, coming to this ground water utilization I have already mentioned in the introduction that how important ground water is to provide spatiotemporal security water security. And this one in this ground water utilization so this ground water utilization is it is run in the developed as well as developing world. In the developed world as well as in the developed nations as well as developing nations so 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 an example from the developing developed world and also an example from the developing world. So, this is for example, in USA in 1975 in USA there were at least not less than 10 states wherein ground water use divided by total water use was greater than 50 percent. So, because I am using the word not at least because I got this one the data only for say 45 out of 50 states that is why I am using this word and added to this there were additionally there were not less than say 9 more states 9 states wherein this is ground water use divided by total water use it was between 40 and 50 percent. So, you can say nearly say at least say 20 percent of the no 40 percent of the states in the US. So, depended significantly on ground water for their for carrying out their activities various activities now and now let me provide an example from India the recent as one say in India during 2004 so the ground water development that is a development stage that is the ground water extracted divided by ground water available. So, this was more than 100 percent in 3 states of Punjab, Haryana and Rajasthan of course this is not a healthy sign, but still you can realize the importance of ground water and we know that Punjab and Haryana are known as the agricultural power houses in India. So, you can imagine the importance of ground water and likewise so in the national capital territory of Delhi also had a ground water stage of ground water development of more than 100 percent and during the same year so there were 5 more states that is Gujarat, Karnataka, Tamil Nadu, Uttar Pradesh and Uttarakhand wherein the ground water the stage of ground water development was between 50 and 100 percent. And so this was also the case of Lakshadvip the union territory of Lakshadvip and of course I forgot to add here so that is 3 states of Punjab and 2 union territories that is Uttes of Pondicherry comma Dio and Daman, D.D. So, this is P Y for Pondicherry and D D for Dio and Daman. Likewise so this is between 50 and 100 percent the union territory of Lakshadvip had as one. So, like as you can say so let me present this in a tabular form so that is India 2004 that is a stage of ground water development. So, let me present this in a scale here so this is 0 and here say 40 percent so this is all in percentage and say this is 50 percent and then this is say 100 percent. So, here above 100 percent we had this is we had the states of Punjab, Haryana, Rajasthan and the national capital territory of Delhi and between this 50 and 100 percent we had Gujarat, Karnataka, Tamil Nadu, Uttar Pradesh, Uttarakhand and Lakshadvip. So, these 5 states and one union territory between 40 and 50 percent. So, there were few more states of Andhra Pradesh, Kerala then there was Madhya Pradesh, Maharashtra, West Bengal. So, you can imagine the importance of ground water utilization. So, here you can see that is say this is 1, 2, 3, 4, 5 and then say 10. So, at least 13 states which covering almost more than 50 percent of the physical area 50 to 60 percent of the physical area of India. So, they developed they were dependent on ground water for significantly. So, this explains the importance of the ground water utilization in the developed world for example, the USA as well as the developing world such as India. So, now let us come to the historical development of ground water in the historical background and we know that the one of the oldest river valley civilizations the Indus valley civilization. So, that time there have been records of ground water wells that is they were essentially open wells used for irrigation or even municipal purpose also. And also the Old Testament it contains a number of references regarding ground water springs and wells. So, around the same period in India. So, during the Mauryan Empire and we know that the Ashokan the Mauryan Empire under Emperor Ashoka it extended all the way from the present Afghanistan to. So, in the eastern India close to West Bengal and even Assam and all. So, there were there are records of ground water wells supporting irrigation and even. So, there were many wells were constructed. So, as to facilitate the the travelers. So, the during those days. So, there were not many communication facilities and so and these one. So, there were many this one. So, the that means. So, this is historically is one of course, I like to show you here that is the same thing that is before moving back to this one. I would like to show you here the. So, which I mentioned here the state wise ground water resource availability utilization at all as you can see here let me highlight the ones with more than 100 percent and similarly Punjab and Rajasthan more than 100 percent Indians this is Haryana more than 100 percent. And I am sorry it is not very visible that is because it is too big a table. So, like that let me also share with you the replenishable ground water resources in India as you can see here in the states of Punjab this is Haryana Delhi then almost in Rajasthan also. So, here there is a significant amount of the ground water utilization added to that is the the states of Gujarat, Maharashtra, Madhya Pradesh, Karnataka, Tamil Nadu and say West Bengal, Uttar Pradesh and of course, here it also this is an old map of India with. So, therefore, it does not show that the new states of Uttarakhand which has carried out of Uttar Pradesh and Chhattisgarh which has carried out of Madhya Pradesh and Jharkhand which has carried out of this one. So, as you can see here a significant area of course, Andhra Pradesh also. So, in all these states the that is the stage of ground water development is at least 40 percent. So, you can imagine the importance of ground water. So, now let us come to that historical background. So, here during the Indus Valley civilization there are reports of ground water use through open wells. So, this is at least 5000 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 references to ground water wells supporting irrigation during Maurian Empire. So, that is and third century BC. So, like this we can say how important is ground water which was realized by human beings in this one. And also now let me also bring it to you at the very interesting technology of horizontal wells. So, we are under the impression that so 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 it has been proved that these horizontal wells have a even greater yield than the vertical ground water wells. And in this regard I would like to mention you mention to you the about canards which are the horizontal wells which were found in which were initially developed in say Iran. So, this is a typical canard and as you can see here in this is a horizontal well. So, this is essentially is the canard. And this the deepest well is known as the mother well and so this is the water intake area. So, basically this is a hilly area or a mountainous area where there is a significant amount of rainfall. And this mother well has a depth of around 50 meters or less than that and there have been examples of mother wells which are even as deep as say 100 meters and one mother well has been reported to be around say 250 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 canard which is essentially a horizontal well horizontal and mild sloping well. So, this is the slope direction. So, this is very mild slope and it reaches the ground and once it reaches ground. So, for a significant portion there is a surface canal and through the surface canal the water is conveyed to the farmland or irrigated land. And in between the mother well and this surface canal. So, there are a number of these shafts and so this is the conduit of the canard which is as which forms the horizontal well. And so these number of shafts are the one which provide access to this drilling this canal. And so this canal this canard. So, this canard was the technology of drilling this canard wherein this water from the aquifer was brought in through the mild sloping horizontal almost horizontal conduit of the canard to the surface canal and then on to the farmland. So, this was very much perfected by people in Iran almost say 3000 years back. And here so the length of the canal canard I am sorry was of the order of say 5 to 30 kilometers. Most of the canards are existing even now. And so they there it has been reported that there are at least 22000 canards existing in Iran even now and which will supply at least which are supplying at least 35 percent of the entire water requirement in Iran. So, here I would like to mention here. So, that is how important is the ground water essentially. So, this is a horizontal well technology which was very much perfected in Iran and from there it when moved on to this Morocco and this other North African continent this continental regions. And then it moved as far as Spain in Europe. So, like this extraction of the historically this ground water has been extracted not only through this the vertical wells also through the horizontal wells. And now let me bring it to you. So, this is 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 case this is basically a pressurized well. So, here we have the that is a free water table is somewhere here. And then in this region where the ground surface is below the free water table. So, there the water is under pressure. And here if we make a if you puncture this one then the water will gush out of this artesian well. And so it will give out water in the form of a natural fountain. So, this region wherein the ground level is below the water table. So, that is known as the region of artesian water where there is a raised water table. And so, if we puncture this artesian aquifer. So, there will be a huge amount of we can get a lot of water. So, these artesian wells also were developed sometime in the middle of this one. And added to this is the. So, in the in 1804. So, there was an instance of the first deep tube well which was dug in and around Calcutta. And so, it had a depth of 500 meters. And so, this tube well was the they can say is the major this one. It indicates a major milestone in this groundwater harnessing or development. Likewise in 1936. So, this Ganga Valley State Cubal Irrigation Scheme. So, here I would like to mention. So, that is the. So, there are at least 22000 canards that is horizontal conduit wells in Iran. Even now supplying at least 35 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 1804 the there was groundwater development through a 500 meter deep tube well or say bore well around Calcutta in India. So, there was a reported. And so, in 1936 Ganga Valley State Tubal Irrigation Scheme was launched in UP with 1500 deep tube wells. Of course, there have been parallely there have been many developments in the western world also. And so, obviously, it all shows how important is the groundwater development. And here let me also show you an example of a horizontal well. And as you can see here there is an aquifer with water table here. And that is there is a sloping side. And so, this aquifer is bounded by an impervious barrier and then say some rock formations here. And so, through this. So, there is a horizontal well. And of course, so the depending upon the water table. So, this we can groundwater can be harnessed to this horizontal well. So, now let us come to the that is the groundwater in hydrologic cycle. So, here I would like to which is also known as the water cycle. And here so, this is schematic diagram. And as you can see so, this is the ground surface. And so, this is a surface water body such as a lake or a river. And so, this is the groundwater table which represents the level of the saturated groundwater which also joins the sea or ocean. And here so, there is a there is a evaporation from the ocean surface from the land surface through evapotranspiration as well as from the surface of a surface water body such as a lake or river as well as through this plants. And then so, all this evaporated water. So, it gets accumulated 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 precipitation which is which may be either in solid form through snowfall or hail storm or whatever. And so, this precipitated water it will percolate through the ground surface. And eventually it will form. So, what are known as the aquifers which are the water bearing strata. And of course, here there is a bedrock also. And then so, there are also among the aquifers there are confined as well as unconfined aquifers. And then so, there is so, these confined aquifers which are at the deeper depths. So, they get their water from this deep percolation. So, here so, this is a deep percolation. And then so, this is the shallow or the top or the water table aquifer is also known as the unconfined aquifer. And so, now coming to this hydrologic cycle, we know 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 here. So, this is the atmospheric segment of the hydrologic cycle. And then so, here there is also so, there is this is evaporation and evapotranspiration. And then here so, this is precipitation. And then so, there is so, this is the surface runoff. And then so, there will be infiltration. And then so, here there will be so, this is the ground water table. And so, here this is the ground surface. So, this is the surface water body. And then here we can say this is a sea or ocean. So, essentially so, this is a cycle. And in this case, now let me explain you the various systems. This quantity is involved here. And as you can see so, this sea or ocean so, this represents almost say 96 percent of water by volume. And of course, so, here there are these so, these are the mountain ice caps. And of course, so, here there is also this is a so, this is the ground water in this confined as well as unconfined aquifers. So, here I would like to so, 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 I am showing one 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 say 96 percent of the water by volume. So, the only the remaining nearly 3 to 4 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 say almost say 97 and half percent of the total volume of water on earth. And only this 2 and half percent is fresh water. And of course, this 97 and half percent we cannot use it for our the to maintain the metabolic activity of human beings, animals and plants. And this 2 and half percent of water and is out of this. So, nearly 70 percent is stored in the polar ice and glaciers. And then so, this 30 percent is stored in ground water. And of course, very little say one fourth of a percent of fresh water is available in the surface water bodies. And here and this so, therefore, as one as we can see. So, this polar ice or glaciers they are available only in the cold regions or high mountainous regions. Whereas ground water is available almost everywhere the fresh ground water. So, and here so, this fresh ground water up to say 1 kilometer depth. So, it is nearly half of that one and then below 1 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 hydrologic cycle. So, the there is a significant amount of earth. Let me go back to again this hydrologic cycle. So, although the entire water the global water volume is of the order of say around 1400 million that is kilometer cube. So, out of that so, nearly 96 say 96 to 97 percent is brackish or salt water or marine water. So, therefore, so this as you can see this 97 percent of water is useless. So, it is only the remaining say 2 to 3 percent of water 2 and half percent of water. So, out of this so, one third of that is available in ground water and this ground water is available in say almost all the regions rather than the mountain ice caps. So, the mountain ice caps are available only in the mountainous regions or the polar regions. Whereas, this ground water is the fresh ground water is practically available everywhere. So, therefore, how important it is to that is a manages ground water. So, to maintain its this one supply and demand and so, that this water table and as you 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 is too shallow then it may create water logging or that is 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 cost many times these days we have the high capacity pumps which are used to extract the ground water like multi stage submersible pumps and so on. So, they are used for extracting ground water through this wells. And 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 a healthy depth of the water table which is neither too shallow nor too deep and we can also maintain the balance between the ground water supply and this ground water demand. So, thereby so, we can provide the water security in the form of fresh ground water which is practically available everywhere in the nearly 29 percent of the land surface on earth. On the other hand so, this at the same time so, this the recent climate change and associated impacts. So, they are also affecting this one. So, that is they are affecting this one and so, these climate change impacts are causing the mountain caps to the polar ice as well as glaciers. Of course, here let me also write here this is a glaciers the melting of glaciers and polar ice. And so, therefore, it is extremely important to see that. So, the water which has melted because of the climate change and the global warming effect. So, is stored in the form of ground water. So, in the next lecture we will see the other aspects of. So, this thank you.