 Hello everyone, welcome to rural water resources management NPTN course week 10 lecture one. We have been looking at water management issues in rural areas, especially due to the increase in domestic agriculture and industrial demand. And we have been noticing that most of the regions are going to be highly stressed in the near future because of the business as usual scenario and climate change impacts. So, it is very important to understand and manage the rural water resources properly, especially for agriculture and domestic land use. Let's look at what we saw in week nine. Because of these issues as I mentioned today, there is a need for infrastructures to enhance the water resources. Enhancing the water resources can be of two types. One is the engineered infrastructures and natural or nature based infrastructures. In week nine, we looked at rural water resource management infrastructure engineers, specifics on how to improve the management of water. We looked at specifically the big concrete and infrastructures that are needed, for example dams and canal networks. We looked at how we could establish a dam command area and a catchment area. A catchment is where the water is caught to be supplied to the dam and then the release of the dam could be your command area. Then we looked at the canal systems as a part of your dam network as an engineered solution to bring the water to the farm. We also noted that the farmers may not be in a low line elevation, thereby pushing water down so you may have to lift it up. That is where we looked at check dams and lift irrigations which are more decentralized in manner. We looked at Ganges water machine for groundwater decentralized recharge and more in depth of how do you get water into the deep deep aquifers of the groundwater. For that we looked at groundwater recharge shafts and manage for recharge schemes. In this week we will be doing mostly the similar focus areas and theme areas but we will be looking at nature-based solutions. So it is again rural water resource management infrastructures but it is nature-based solutions. Specifics on how to water manage in these scenarios is going to be given by rainwater harvesting through natural methods, natural infrastructures that can be used to store the water like depressions and lakes, vegetation induced infiltration. How do you enhance the groundwater recharge through vegetation induced infiltrations and more importantly, a forest station in Agroforestry. So let's jump into this week's lecture. Given the water issues, what are the available infrastructure we have? So I have given a quick example of the water issues in India, especially for rural India. So what are the available infrastructures? Let's look at it. We did look at this definition of water security. And in the definition of water security we had the four pillars which is drinking water, economy, water for economic upliftment, ecosystem services and resilience. So where do you think nature-based solutions fit more? Yes, all these infrastructures would have to enhance drinking water supply, provide water of economic stability and provide resilience to climate change. For example, droughts and floods. But more specifically, it has to be providing the ecosystem services because you are a nature-based solution. Drinking water, tanks, underground tanks, sumps, etc. are clearing the land, clearing the soil, putting concrete, etc. Then by reducing the ecosystem services. I hope you understood last time when I discussed this water security theme. We have to be careful that if we do engineering, your ecosystem services are going to be disturbed. The dam is there, water flows. And what happens is water is stored, but then downstream the ecosystem services are compromised. So that is where we need to be careful on releasing the water in a timely fashion for nature-based ecosystem services. So today's lecture or this week's lecture will be mostly focusing on the ecosystem services. Yes, it will go through all of it, all the four themes. But most importantly, it will look at where does rural water management, which is nature-based solutions, help the ecosystem services and more stability to the ecosystem. So now there are two types of rural water harvesting networks and rainwater harvesting networks. So let's look at the two types of rainwater harvesting using nature-based solutions. So the first theme we're going to look at is capturing the rainfall and then using it for different aspects. So how can we do rainwater harvesting? Surface runoff rainwater harvesting is the first theme where you capture the rainfall after the runoff has been generated. Mostly to store rainwater for future use. Diversion of the water, so rainfall hits on the roof, plants freeze on the road, and then it turns into runoff. Then you capture the runoff for future use using diversion, ponding, channelizing, etc. Or water for agriculture, livestock, domestic use. But if you pond it, you have to be using it before the evapotranspiration losses. So that is the first type of rainwater harvesting where you capture the rainwater and use it for surface applications. Be it storage or be it applications such as agriculture, which is on the surface. But there is another type of rainwater harvesting also, which you can do groundwater recharge using rainwater harvesting. Where in you convert from surface to groundwater, because you're capturing the water and instead of letting the surface water runoff to generate, you are pushing the water into the groundwater. Once the water is infiltrated, it can move further due to gravity via percolation and increase the groundwater storage. So aquifers can be a storage unit, because you have a big groundwater storage unit under the ground in porous spaces. The space between the solid, the sand particles, you have spaces where water can store. So those spaces collectively can be a storage. And it can be a leaky system also because once you build a water table, it will start flowing from high potential to low potential to the reverse streams or even your oceans etc as base flow. If you look at the traditional methods for rainwater harvesting, most of them were having this groundwater ideology in the background. For example, we would have a village stand, village pond etc, where all the street water would be channelized to go to this pond and lake. But the pond would not be lined underneath, whereas water would be just going down as infiltration. There was much less use for agriculture, like capturing the water, putting it into the pond and agriculture, because there was no pumps. They would use it for domestic use like drinking, bathing and your animal washing etc. But not much. New methods are rarely implemented in rural India. If you look at it, if you go there, it's more traditional based knowledges and less newly applied methods. However, the recent visits I'm also seeing that the old traditional methods are not maintained well. If you go back to the previous lectures over the weeks, we have been debating that if they don't maintain, it is a big loss and they lose the system. Okay, so let's look at the nature-based rainwater harvesting or natural rainwater harvesting or nature-based. The question is, are you using less concrete, less construction for rainwater harvesting? I would say zero, zero construction etc. But still you have to do some movement of stuff, so there is more nature-based solutions. And you would also use natural settings, not leveling the field, not creating bunds etc. It is all naturally built. So let's see what is the benefits of natural rainwater harvesting and we'll look at some examples this week. It is less engineered example or that is less land is cleared, less concrete is poured on the ground, less need for concepts of designs etc. So if you're having, for example, a land, you're having a land and you're wanting to store the rainwater. You don't clear this land, you don't make it straight, which is done in the engineered method and no trees and plants are lost. Okay, still keep them. You would try to build storages in between the existing nature's benefits and nature's parameters rather than removing it and making dams and checkpoints. So how do you evolve together is nature-based solution. Moving on, use of existing topographic features. The first thing is you're not leveling the field. As I said, the undulations, the up and low of the topography is preserved. Example slope, you have a slope, you don't make it straight or dig it more deep and then pour all the water in. Now you're going to get an idea that these are not big systems, nature-based solutions are more smaller, more decentralized and localized. This is what the ancestors did, the traditional methods, easier to maintain and you're not stopping a lot of water, which could be of use for others. You're recharging small volumes, you're also bringing more water from outside, the rainfall and channelizing, etc., and bringing it into these small ponds. You're not clearing the land, you're not making the land straight, etc. So basically all the land, all the vegetation, etc., is preserved. You're just making some small changes and also maybe bringing some nature native species and you are putting it into these structures. Less people relocate and this is very important. You're not asking people to leave the land and go because you're going to have a dam. You're going to be in between the houses, in between the villages, how can you do it? So one quick example would be this. So if you look at it, the slope is not compromised. The slope is not taken away, the slope is slow. So I would say that I would, for example, you could say, oh, why don't we make it deeper? Why don't we straighten it so that the water stays in here? No. So that will be more engineered. Why can we make a wall which is more cement and concrete? No, that will be more engineered. So what do you want is something which is very nature-based and here you could have seen that the land has been identified as a slopey land. A small pebble rock-based dam is created wherein water can go in and store. There is also a small dug well which is dug just removing some soil out. All these dug wells could be kind of between the nature-based and engineered because you're not putting too much of engineering and you're not clearing big land. So there is a bund and here you could have, because of the water, even if water stays there, all the plants would die. So you could remove some of the grass, not the trees. Look at it, the trees are kept as is and people are not relocated. So once water gets stored, it gets to infiltrate more and by infiltration it can recharge these wells and other locations. What could be the compact difference between the structure and the engineer? What I'm asking is how much of water would be recharged by these kind of systems compared to a dam or a pond or a recharged pit? Is the question. So do you think there will be much differences? Yes, these are more slow and the volume is more or less because you're preserving the environment. You're not clearing the land. If I had cleared this land and made a big pond or an embankment with all these material, I would have more water to store but I didn't do it. What I did is rather I preserved the slope, I preserved the condition by using the local materials and I infiltrated the water. This is what has to be taken by nature-based solutions. It's easier to dismantle also. Just think about it. You just remove the boulder, let the water to flow and the system can reproduce into a forest or a grassland like this, like quickly. However, if you do it with engineered systems, they will not re-bounce back to the original state. It will take a long time. So the impact is high. But understand that it takes time for clearing. You are losing some features in engineering whereas less features are lost in the nature-based solutions. Let's take a dam which can be a nature-based solution and less impactful on the surrounding. So the other aspect is the nature-based solutions are less negatively impacting the area. Even though the water is also a low recharge is happening, low storage is there. However, the impact on the ecosystem on the nature is less. This could be the same by using an infrastructure with some features to consider nature. Let's take a leaky dam for example. What is a dam? A dam has to store water. It should not have leaks. It has a gate where you can open, send the water. It has a channel where water can be released. But what is a leaky dam? It is purposely made to leak from the walls. Rather, water is stored, water comes and gets collected and it is constructed very leaky so that water can still pass through. So you have some water, yes, but then water can still pass through. So look at this book from FAO and Images. You could see that storage structures that are purposely made to leak. You're bringing the rocks and making these step dams and making sure that water can pass through and if water passes through, it gets to recharge and get more water to the ground. Loose construction and let it be small. If you look at the construction itself, it is not big as a big dam. So nature-based solutions are small and loosely constructed so easily people can construct and just bring all the rocks and then make it. If you think about it, this is how the natural setting the animals and small insects would also do. It would make something just bring some materials like a bird building a nest. That is not a construction, right, even though it does make a nest by bringing twigs and making a weaved nest. It is not called a constructed nest. It does not impact the nature much. Same way here, you're bringing all these. You're using wires, for example, steel wires to hold on to the rocks and the water goes slowly. Wire materials to hold rather than cement. Think about it. If you use cement, water cannot pass, but you use steel wires that can actually hold the rock so that the water can pass. The major aim is to slow down the water, recharge the ground water and reduce soil erosion, because when water flows fast, there is a lot of soil erosion, whereas the recharge would take time. So, to slow down, so if you slow down the water, you can get more recharge. The thickness are given by FAO, which is just one meter, not too high, just one meter and thickness is around 0.7 meters. So you can easily collect the local materials. I said the nature-based solutions have local materials. You don't have to bring cement. The wire, yes, the wire, you may not get it inside, but you can see the point. It's not fully constructed, and you could see that all the area can still get water because of this, and it is going to enhance the nature of biodiversity. You can make it also cascade as I was showing in the engineer system like a check dam. Whatever approaches that we use for check dams can still work here, but most importantly, it is leaking. So, more water will pass through the check dam like this. So you build one leaky dam, and then this water will go to this one, this water will go to this one. So slowly, slowly it pours, and then water moves. So if you look at a check dam cascading impact in a constructed manner, the water would actually stay in one dam fully. It has to be fully coming to the brim level, then it goes to the next, then it goes to the next. But here, since you have rocky, leaky material, water will go, stand, and then still continue flowing down, even though the full dam is not reached, and then goes down, goes down again. So this is one type of materials that you could use to construct leaky infrastructures, so that water is always flowing, you're not totally taking the water out, but there is a lot of nature based solutions. So there are a lot of specific treatments as given by FAO. So this manual I'm sharing, which is the chapter 3, the link is given below. You can go and check a lot of materials that are relevant for these treatment measures. So treatment, as in what type of check dams can you build using the nature solutions. So you can build loose stone that we saw in the previous one, boulder check dams, big, big rocks piled behind one another. Brush fills, so you can have these dams. Inside the dam, you can put some soil and grow some brushes or like small, small plants. So they will fill the space, so the leakage would be there, but even more reduced. So if you have 20% water leaking in the loose sand, we'll have only 5% in the brush fill, whereas it is 0% in a cemented check dam. Earth plugs can be done. Here you put instead of cement and concrete, you can put in soil that can be there. So soil is not totally impervious, right? Water can still pass through. So those kind of earth plugs you can put. And most importantly, they don't harm the nature. So for example, a check dam is broken. What do people do? They just leave everything, go to the next location. What happens to the rock, the cement, it doesn't degrade. Whereas here earth plugs, brush fills, everything will degrade and then become soil again. So that is also what is called more as a nature-based concept. If you let it go away or not use it, it will still bounce back into one of the nature products. For example, I have a steel bridge. The steel bridge falls down. What would happen? The steel is steel. It just rusted, maybe 1,000 years, maybe 500 years. It's just going to be as a steel and slowly rusted. Whereas if you take a wooden bridge, if it falls, within 10 years or 5 years, it will degrade, go back as soil carbon, get taken up by the plants, and then live as another living organism. So wooden wire check dams, and we have seen that in the last assured check dam where you can make a check dam using wood rather than rocks and pebbles. Log check dams, big, big logs can be treated and then put. All these are nature-based solutions. So you see here how you are coming out of using bricks and stone and mortar. Rather than using earth plugs and rocks and stones. This is the first example I would like to consider where you have a rock base check dam. Inside it, there is some soil which has been inserted and along the inserting, you put seedlings, small plants. What happens is the plants would let the roots go in. So once the roots go, the soil is held tight. So even if water comes, it won't wash away the soil totally. It won't wash away the plant, but slowly the water will be released. So here's how you convert a concrete system. So a plant cannot grow in concrete, right? One way one on the walls you would see, but not exactly as a full plant, but here it can grow fully and still work as a dam. Okay. Here it is just using big, big boulders rather than concrete and in between you don't have anything. So water will just flow through as a leaky stone dam. So what we've seen here is we've taken only one concept as check dam. And then we've seen how we could build it on a location by not clearing the land, by not making it leveling, level through concrete networks or bringing a bulldozer and making it straight. You're making small nature-based check dams and when I say nature-based, it has to be built using nature concepts. Rock stones also are included. When you convert rock and stone to a cement, that is not included because you're engineering. Here we're just using the concepts and also most importantly wood and forest material to build these kind of networks. So that is the first part. You have a nature and nature-based solution. The next part of nature-based solution is, is it completely storing the water or is there some aspects that can help in release of water? There's no engineering. There's no valve to open and close. So water can still flow down using gravity, but at a much lower pace. So as I said, all these studies have been testing all these and looking at different methods to evaluate these check dams and traditional methods which were lost during the previous centuries. Why was it lost? Because they didn't want to let the water go and they didn't want to manage it. If you engineer it, the management time is less because it will stay there for a long time. The rocks are not loose. So why would they move? But if you pile up the rocks and then water comes, it will slowly lose out. It's like building a castle on a beach. If you build it with rocks and plastic, it will stay even if a wave comes. But then if you build it with the beach sand and then make a small puddle, then water comes and then it moves away. So each time there is good maintenance, you can rebuild it again quickly, but it's less expensive time consuming those kind of aspects. So if you have the time, if you have the labor for the people, through the people, it is always best to have nature-based solutions. In fact, big, big countries and developed countries like Singapore, Malaysia, they are getting into these nature-based solutions so that, yes, they store the water, but also they don't harm the environment because they want to store it. With this, I will be happy to show more examples from the next class. I will see you in the next class. Thank you.