 Welcome to the rural water resource management course week one lecture two. We will be looking at the different of the hydrological cycle and why it is important for understanding to manage India's rural water resources. So, the importance of water resource management in India introduction to hydrological soil cycle and representations. Let's look at this water cycle or the hydrological water cycle. USGS from the US stands for US Geological Survey and they have done a very comprehensive representation of a hydrological cycle. Please understand that this has been done for the US region but most of it would still apply for Indian context. If you look at major hydrological components, soil research, etc, we still follow the US norms. So, that is why I am using the representation of US Geological Survey. So, let's start here. In this entire cycle, we could start anywhere and it has to come back to the starting point. So, for convenient purpose, let's start with the atmosphere. In the atmosphere, we have clouds which convert or condense water into precipitation. So, it has a couple of different formats but we will go through that when we look at each component in depth in the coming weeks. So, let's say one type of precipitation is rainfall. So, water vapor from the clouds convert into precipitation then it hits the land and converts into runoff. So, you could see here that some permafrost and snow are also being converted into runoff which is basically water moving on the land and you could see precipitation flowing into the reverse as runoff. Whenever the arrow comes down, it means it is going from top with the atmosphere to the ground and whenever it is an up direction, it is coming from a lower potential to a different potential or from the ground to in this case from the ground into the rivers and lakes. So, some of the water gets infiltrated and moves into the groundwater and within the groundwater, you have multiple directions. One goes in as deep aquifer or deep groundwater and then there is some for shallow groundwater. Then what happens is some of the runoff converts into rivers and then gets stored as lakes, ponds, etc. So, you could see some of them being stored but some do manage to come out of any storage units and then come back to oceans. When it comes to the oceans, please understand after some time, it does evaporate. So, that is captured by this term. So, as I said, it goes from the land to the atmosphere by the top arrow. So, you could see that evaporation happens and all these freshwater gets converted back into water vapor and then clouds. So, this is how a simple cycle I have explained but we will go into depth in each component which is relevant to India and especially Indian rural regions. So, when we talk about rural regions, we would eventually do not consider volcanic steam, ice, snow, glaciers, thermofrost, etc. Because most of the rural regions in India is going to be arid or semi-arid which means not that much or I would say even zero snowfall probability. So, most of the agriculture can be using snow, water, and melt which is coming from here down, for example, into the Bihar regions. The Ganges has a lot of snowmelt composition but we would, as a land hydrological process, we would look into what are the driving forces, driving parameters here. Please understand that all this is there but we also have a sun. Why would the sun be there? Because in the water cycle, it is one of the most important drivers. All this would shut down if there is no evaporation. For example, let's take two components which are very, very important here which is precipitation, which is conversion of your cloud material into the water vapor into a liquid phase and comes to the ground. So, that is your precipitation and then the second part is your evaporation or evapotranspiration. So, if your precipitation doesn't happen, there is no water on the land. Everything is in the cloud. Same thing, if evaporation transpiration do not happen, then the water is stuck on the ground. For example, the oceans would be full of water and no water evaporates up and the plants do not transpire water back into the atmosphere. So, the cycle would be stopped. So, this cycle is driven by your sun. If the sun shuts down, there is no evaporation. If there's no evaporation, there's no water vapor forming clouds and the cycle of sun and moon also helps in pulling down and condensing the water vapors. So, the precipitation will not happen if there's no sun and all of it would be one phase which means the cycle would be stopped. Whatever water remains in the ground would be there. It will not evaporate and there is no plant life, etc. So, that is why they have put the sun in this picture very carefully. So, this is a very general representation of a hydrological cycle. We would get into the details as I said on each component which is necessary for rural India. Before that, let's look at how much water is there, how much fresh water is there for the world and then for India so that we have a context. We have to build a context like, yes, I've seen cycle, the water cycle, the different components, but how much is it there for human consumption or human-related like food, ugly culture, drinking water, etc. It will be a very interesting factor. That's why if we know how much we have, we get to understand that the importance of water resource management as the title of the slide suggests. Let's take the water, total water. What you see here is around 97.5% of the total world water is in oceans. Oceans sees all the salt water. So, all of this is saline water or high in salt content which is not usable. So, that would not consider as a fresh water. Fresh water does not have that much salinity. So, if you look at it, only 2.5% of the total water in the world is fresh water. Plants do not grow on ocean water. Please understand humans do not consume it without high intensive treatment like desalination plants. So, it is important to understand that of the hydrological cycle, we're only looking at 2.5% of fresh water to manage. So, it is very, very important to manage this 2.5%. And even the 2.5%, not all is usable. Let's break it down. So, of the 2.5% of the fresh water, 80%, almost 80%, 79% is locked in ice caps and glaciers. So, what you see as glaciers and ice caps moving in the Antarctic, Arctic is all fresh water because it is snow, ice, when you when you meant it, you can drink it or after purification. But it is not readily usable. So, the readily usable is only the remaining 21% of which 20% is groundwater, which is under the ground. And there are different stratifications. So, right now, all the groundwater is put into this pool of 20%. Not all the groundwater is easily accessible. A very, very subtle amount, a very small amount is accessible. Let's get into the details of that when we talk about groundwater. However, of the 21%, which is easily or relatively easily accessible, 1% is easily accessible as surface water. And of the surface water, that 1%, 52% is easily accessible, surface fresh water, which is your lakes, ponds, your big, big rivers, dams, etc., etc. So, all these water that you see, for example, in Ganges, Nile, Yamuna, everything would contribute to 52% across the world. I'm saying this is not for India. Again, this is for the world. Of the 1%, 38% is in soil moisture, which is the water which is held in the soil, which is readily accessible to the plants. So, understand that the soil moisture is a key component for plant growth and for living organisms in the soil. So, the soil moisture which is held in the soil, the water particles, water molecules that are held in the soil is around 38%. The remaining is atmospheric water vapor rivers, water within living organisms, etc. So, if you combine all this, we get around 1% of fresh, easily accessible water of the 2.5% and now I'm going up. So, all this is 1% of the 2.5% and of the 2.5% of the global water. So, you have a very, very small component. Water is salty and in oceans. Again, there has to be a process by which the salt water from the oceans convert to water vapor, which is driven by your sun, evaporation and then comes back down. Not all of the ocean water is evaporated. There's only limited amount of evaporation happening, limited clouds. So, you don't see all the water in the oceans evaporate. Even fresh water is locked. Please understand this. It's a very important point, even though we have 2.5%, not all the water is readily accessible. Easily accessible is a very small portion, very small, as I said, 1% of the 2.5% of the total water. The numbers now. So, 20 plus 1% is the total water available, easily available, of the 2.5%, which are 0.5% of the total water volume. I'm pulling down groundwater here also because in recent years, the access to groundwater has increased. Because of scientific technologies, there's a lot of pumping that happens and a lot of new innovations in pumps cheaper, cost effective pumps have come to the market. So, a lot of people are easily accessing groundwater. Is it sustainable? That's a different question. We will come to that when we talk about the rural water management. It is not sustainable. But still, in this context of the slide, how much water is available? How much can we access? So, if you do the numbers, 20 plus 1% of the 2.5% is accessible. I'm putting all the groundwater, which is approximately, still only approximately 0.5% of the total water, which is a very, very small component. So, it is very important to manage water. Let's look at the numbers as a table. So, if you have 100% total water, you have 96.5% locked in the oceans, seas and base. Ice caps, as I said, the solid ice water, which is locked in ice caps, glaciers and permanent snow, you cannot access. The groundwater is around 1.7% of the total water. You would see some differences between FAO's estimations in the previous slide and some people, some scientists' estimations here, but almost they agree in terms of the volumes. So, the percentages might be just a little bit off, but it is almost the same. How much water is easily accessible is very, very small. So, of the groundwater, 0.76% is fresh water and then of the total water and saline. So, it's not all the groundwater that is usable, as I said in the previous slide. And then you have the soil moisture, which is very, very small given for the plants to consume. And then you have groundwater, lakes, and even the lakes have bad quality water, which is saline, which is not portable. So, only fresh water is very small. So, if you look at the numbers, even lakes and rivers, 0.002% of the total water volume is very, very small. So, if you add up all these numbers, 0.76% in the groundwater, 0.007%, 0.002% in the rivers, it approximates to around 0.5%. So, this is the difference between the estimates. Here, we had 0.5% approximately. Here, we have around 0.877%. But still, again, it's a very small volume of water at an annual scale. So, it is very important to store it. Because of this, what has happened? This picture from WRI shows where the water stress is high, that it could be very, very high in the near future. So, this is the baseline water stress. You could see that India and all the countries along the equator with a higher temperature region are facing extreme water stress. Also, those regions which have agriculture as the major crop or livelihood will have a lot of water stress. This also shows a high contrast between developing nations, underdeveloped nations, for example, here in Asia and then developing nations like India and highly developed nations like US and Europe, etc. You could see that there is a stark difference in the water stress. Are they managing the water well? What are they doing different? This is very important to understand before we jump into the management of water. The water stress is not the same across countries. This needs to be understood. Although we have the similar rainfall patterns, similar temperature regimes, we have different water stress. Why is that? Why is this disparity in water? Because of how a nation uses the water, how a country prioritizes the water use. Let's take the world example. The world, 70% of the water is given in agriculture is the average. In 20% is used in industry and 8% for plastic. So, the human consumption is very, very small. On the whole, agriculture takes more water. This is the average world across the world. So, if you come to low and middle income countries or low, underdeveloped and developing nations, India comes in this ranking also. You would see that if 100 liters of water is there, India would spend approximately 82 liters on agriculture, whereas 10% is given to industry and 8% for domestic. So, the 8% is still almost the same. So, we're not going above and below. But if you look at where does the water, most of the water goes, it goes into agriculture. Most importantly, it goes above the world average. So, if the average is 70%, still this low and middle income countries are pushing a lot of water into agriculture. And the agricultural produce does not get that much price. On the other hand, if you look at high income countries like the US, Australia, Europe, you would see most of the water is used for industrial applications, cars, computer technologies, etc., etc. Whereas 11% is domestic. So, they have a higher quality of life. So, they would have higher access to water, almost double. So, their quality of life, how they use water resources is pretty high. So, they will have a higher consumption, which is okay. But if you look at the agriculture, they're very, very small compared to the average and the high and low middle income countries. This clearly shows where the priorities are. So, for low and middle income countries, it is agriculture where they put a lot of effort and water into agriculture. Whereas, in high and high income countries, developed countries, the water is put in industry. And because of this, maybe the industrial produce is getting much, much higher benefits, economic benefits compared to agricultural produce. And that is one of the reasons maybe the high income countries are still high income countries and low and mid income countries are still getting poorer and poorer by day. Because the agricultural produce is not getting the price, there's climate change impacts on agricultural produce. There's losses whereas in industry, it's almost the same. Okay, you are kind of mitigated against climate change. So, this is the reason why we see this water stress being different in different countries. It's not only the population, it is also the livelihood. The population is very less, but then the livelihood of options of the people where the water is spent is very, very important. Let us compare the water. But before that, the most important part, when we start the hydrological cycle, when we want to do these percentages, we need to calculate water. And while accessing these data, please note the units. Units are very, very important in this research. Okay, so when you do hydrological cycle, as we saw in the hydrological cycle, there are multiple parameters, multiple variables, multiple compartments of water. And each one would have a different unit. It's very important to bring all the units into one, which is normalize it. And so that we understand how much is rainfall, how much is groundwater, how much is stream water, the domestic use, etc. So, please look into this carefully. So, for example, let's take some examples. Rainfall are always measured as depths or weights, depth as a thickness. So, when you go to the news, they will say we had rainfall around 15 millimeters over the monsoon. So, 15 millimeters is a thickness. It's a scale one dimensional thickness. You can convert that into a volume if you multiply it by the area, which you see here, volumes of water. And you can also convert the rainfall into a rate. You could see that 15 millimeters across the monsoon, I said. So, 15 millimeters across three months. So, if you divide the number of days, you can get per day how much is the rate. Normally, the amount of rainfall is given as per day, like every day this millimeters is recorded, or an intensity, which is a rate per hour, or most importantly, in a national context, you will describe it as a unit per year, because all the water balance components are per year. So, you would say 600 millimeters in an arid region in Gujarat per year. If it goes to Maharashtra, for example, along the Western Ghats, you get around 3,000 millimeters per year. So, this is a thickness. You can convert it into a rate. All these are dependent on the research you do. So, the first point I would like to stress here is, please look into the data and the units. If your units are not the same, you need to convert them before you compare between rainfall, groundwater, industry use, etc. If you do not, then it would just not make sense. The additions will not add up. So, volumes of water is also present. You can do it as cubic feet. Also, within the units, within the rates, depths, and units, you also have different ways of expressing a unit, a dimension. For example, you can tell volume of water in cubic feet, gallons, cubic meters, acre foot, etc., etc. Acre foot is an area times a thickness, which is a foot. So, all these things, please go through. The books I've recommended have it, but most importantly, when you download the data, the unit would be given. Discharge is the amount of water which comes in rivers is a flow unit per time. For example, you tell cubic meters per second of speed, the velocity of water in the river. So, rainfall is in precipitation, comes in as millimeter thickness of water depth that converts into runoff as a velocity. So, all this you can still convert it back into volumes. Normally, volumes is good. So, if you convert rainfall into volume, if you convert discharge into volume, you can get into comparing it. So, you can see here cubic feet per second. If you compare that or convert it to per day, then you just multiply a number of seconds per day and you would get a cubic feet or a cubic volume. So, this is how you convert everything into one unit. I said there are multiple units. So, please do not get confused of how these units are organized. All hydrological books, most of the good books would have a unit table either in the front or in the app index. You can also get these conversion rates in online modes. So, you can look here, you can convert centimeters into inches, just multiply. So, there are two basic units. One is metric and one is English units. Because we were under the British rule, we have a confused system that some of the units are still in English and some of it are in metric or SI units as we go. So, most of the world uses the metrics, but some English units are still being used. For example, if you go to a shoe shop in India, you still order by feet, inches and stuff. If you tell your height, it is foot and inches. Whereas, in other countries, it will be centimeters. When we go for a distance, it is kilometers, not miles. So, this confusion does exist. So, please when you do the calculations for water, area, etc., please make sure you understand which unit you are using. For example, area, we do have hectares and square kilometers. It is a very common term. But when you look at some education reports, you look at as acres, which is English units. So, you see, you need to convert these two units. Otherwise, this calculation will go wrong. Just look at how much difference the decimals it will come. So, always convert them and be careful. So, that is one very important point I would like to mention before I conclude. So, we talked about the hydrological cycle. We looked about some components in the hydrological cycle before we introduced how much fresh water do we have to conserve. And then, we looked into some units. And before the next class, please go through some of the units to have an understanding because we will be discussing about the ways of how water is being used. Thank you.