 Myself, Sandeep Javeri, Assistant Professor, Department of Civil Engineering from Walsh Institute of Technology, Sholapur. In today's session, we are going to discuss storage reservoir. The learning outcomes. At the end of this session, students will be able to explain the necessity and selection of site for dam or reservoir. So, students will be able to explain the structure of dam. Now, the reservoir is an artificial lake which is formed on the upstream side of the river by constructing a barrier or a dam like structure across it. So, the constructed barrier will form a reservoir. A reservoir has two categories depending upon its purpose. If we are using a reservoir for storage purpose, it is a storage reservoir. If we are using a reservoir for distribution purpose, it is called distribution reservoir. As we know, the demand of water is more, but supply is less. So, for that, it is necessary to construct a reservoir and dam across the river. Now, this is a photograph for reservoir. We can see here, this is a large catchment area which is available on the upstream side of this dam and there is a narrow valley which is provided on the downstream side. There is a spillway which is provided here inside the dam. The purpose of spillway is to expel out the excess water from the upstream side to the downstream side of the dam. This is another sketch for the reservoir. Here you can see this is a dam or a barrier structure which is constructed and this is the upstream side of this reservoir and this is the downstream side of this dam or reservoir. So, through this dam, we are providing the openings inside the dam and through this openings, the water is allowed to pass from upstream side to downstream side. Now, what is the necessity of providing the reservoir or dam like structure? The first important thing is to control flood and drop that electricity using the water. So, generation of electricity that means for hydropower purpose, then for irrigation purpose that is for cultivation of land, we require water. Similarly, we require water for domestic purpose that is for drinking purpose. For navigational facilities also, we are using reservoir and additional utilization is to develop fisheries that is for business purpose, we also require the reservoir. Now, what are the parameters required for suitable site selection for dam or reservoir? So, let us see one by one. The first parameter is availability of suitable foundation. As we know, the foundation is very important parameter while constructing any kind of structure as we are going to construct dam for a period of 52-75 its lifespan, so the foundation should be strong. The second parameter is the river valley should be narrow at dam side that is on the downstream side because of that the length of dam required will be less, so it becomes economical. The third parameter is the river valley should be wide at upstream side. The purpose is to store maximum water. As we know the demand is more, the supply is less that is water is shortage, so for maximum storage of water the river valley should be wide at upstream side. Then another important parameter is the river bed level at the dam side should be at higher level than the river basin. Because of that the storage of water will be more that concludes or that will result in the total volume of water which is available for the requirement of human beings will be more. The reservoir basin should be leak proof that means there should not be any leakage which will again create a trouble because the purpose of dam is store the water and to distribute the water for various purposes. If we are storing the water on a basement on a basin which is not leak proof or which allows seepage of water below the surface of basin, so this will create a problem for the purpose of construction of dam, so the reservoir basin should be leak proof minimum land and property should be submerged while considering the site selection for dam. The another parameter is the dam side should be accessible to the cities that means the distribution of water the time required for the distribution of water will be less and the cost is also going to be reduced. The project should be such that it should meet the increased demand of water in future. That means we construct a dam for considering the next 50 to 75 years span of life of dam and also the storage of water should be such that it can use for the further growth of human or people for the next 50 to 75 years. Now let us consider the structure of the dam, now this is the cross section of the dam, so here this is the upstream face or upstream surface or upstream side of the dam, this is the downstream side of the dam. We can see here there is a water level, normal water level and maximum water level, the difference between maximum water level and normal water level is the free board. Here spillway is provided within the dam, it may be provided near the dam or away from the dam, the purpose of spillway is to expel out the excess water which is available in the upstream side to the downstream side. The also important thing of the importance of spillway is that it protect the dam structure against the falling down. Because what happened, if the flood is happened here, if the excess water is available here then that will damage the structure of the dam, so to avoid that we have to provide spillway. Now there is a sluiceway which is provided which helps to collect the silt which are available here and that silt we can remove by constructing the sluiceway. There is a gallery provided, it is a small room like structure which is provided inside the dam for the inspection purpose. So whether there is a leakage happened within the dam that we can check out and we can maintain the structure of the dam, so this helps for the maintenance of the dam. Now this is a hill portion of the dam, on the upstream side the dam is resting on the river bed, this is a base that is called hill portion of the dam. Then in the downstream side the portion of the dam which is resting on the river bed it is a toe portion, it is just like a resting of feet on the ground surface and this is a topmost part of the dam cross section that is called crest. Now you are supposed to pause the video and answer these questions. Now these are the answers, as we know the first statement is true because the purpose of constructing reservoir or dam is to store the water for future demand and to distribute the water for drinking and irrigation and industrial purpose, so the first statement is true. Now the second statement is false because in case of selection of site for the reservoir basin it should not be leak proof, but it is a false statement as if it is a leak proof then and then only we can store the water in the reservoir basin, so that is why the second statement is false. These are the references that we are using for creation of this video, thank you.