 Hello, I am Dr. Satish Kumar Kashyap, Professor in Civil Engineering from Balchan Institute of Technology, Soolapur. In this video, I am going to discuss Reservoir Planning, Area Capacity Curves of a Dam Reservoir. Learning Outcomes At the end of this session, the students will be able to explain important reservoir levels and different zones of reservoir storage. The students will be able to describe the Area Capacity Curves of a Storage Reservoir. The students will be able to estimate storage capacity and subversion area of a dam at any particular level using Area Capacity Curves. Coverage. Just we will have a brief discussion about Reservoir and their purposes. Then we will discuss about important reservoir levels, then Reservoirs to range zones, then we will glance through capacity surveys of reservoirs, then we will discuss Area Capacity Curves of a Reservoir, and then we will see how one can use Area Capacity Curves for fixing important levels of a reservoir. You know that reservoirs are used for human consumption and industrial use. Also for irrigation, also for hydropower, also for hydropower plants. We also construct dams as flood control dams and we also construct dams and form reservoirs for the immunity use. This may include for boating, water sports, fishing, sightseeing and so on. Now this is a typical river valley development. This is a Damo river valley. So you will find these reservoirs which are constructed by using dams here. So the reservoirs are well spread over the catchment area so that every dam will have its own catchment and will receive sufficient water to satisfy the demands. Now this is a reservoir which is formed by construction of a Tehridam. Tehridam happens to be one of the highest earth dams constructed in India and not only in India but the world having height over 250 meters. And see the water level it is very low at this particular moment. In one more picture I will show you the water level has come quite up and now water has reached up to spillway and excess water is diverted downstream through this particular spillway. So here you can imagine that the water contained in dam will be different at different levels. So let us understand important reservoir levels. First important level is maximum water level. So it is the water level ever likely to be attained during the passage of design flood. It means it is not expected that water level will rise above this. Of course it depends upon the specified initial reservoir level and the spillway get operation rules. Then second important level is full reservoir level. It is the level corresponding to that which can be maintained without spillway discharge or without passing water downstream through fluids. It means it is the level up to which we store the water normally. Whenever there are no floods there is minimum drawdown level. It is the level below which the reservoir will not be drawn down so as to maintain minimum head required for power projects. It means this MDDEL is important especially for the power projects. Whereas there is one more level dead storage level below this level there are no outlets to drain the water in the reservoir by gravity. That means whenever we have canal outlets so it is the spill level of the canal outlet below that water cannot be drawn into the canal that is the dead storage level. So this figure will give you the idea about the levels. So this is the maximum water level which is attained at the time of floods design floods water is not expected to go above this. This level is of course top of dam. This is FRL that is full reservoir level which we maintain whenever there are no floods. So these levels are again against the gates against the gate. This is the spillway crest level. So whenever there are no gates provided you will find the spillway crest level itself is a full reservoir level. But when your gated spillways are there we define these levels. Now if you are using this reservoir for hydropower generation so this is the minimum drawdown level so that minimum head is always there above the turbines. It is uneconomical to generate electricity when water level goes below this minimum drawdown level. Whereas this is a dead storage level which matches with the spill level of the outlet of a canal also. You can also have outlets below this level but they will open in the river. Now important storage is in a reservoir. One is a live storage. So this is the short storage available for intended purpose of a reservoir between full supply level and the invert level of a lowest discharge outlet. So this is the most useful water for satisfying the demands. The dead storage it is the storage below the invert level of lowered discharge outlet from the reservoir. It may be available to contain sedimentation provided the sediment does not adversely affect the lowest discharge. Floor storage it is the storage between full reservoir level and maximum water level to contain the peaks of floods that might occur. So here this will give. So as we discussed this is full reservoir level. This is the storage which is used at the time of flood control level and this is the searcher storage it is matches with the highest flood level. This is the conservation storage which is used for satisfying the demands let it be for irrigation let it be for hydropower and so. And below this dead storage level whatever the storage is there that is called as a dead storage. So in this way the storage zones are important for us dead storage this is a live storage this is the flood control storage and the searcher storage. Now let us go for two small questions. The searcher storage in a dam reservoir is the volume of water stored between minimum and maximum reservoir levels minimum and normal reservoir levels normal and maximum reservoir levels none of above. One more question the useful storage in a dam reservoir is the volume of water stored between minimum and maximum reservoir levels minimum and normal reservoir levels normal and maximum reservoir levels none of above. Just see the searcher storage is the storage between normal that is full reservoir level and maximum that is highest spread level whereas the useful storage is between minimum that is dead storage level and normal reservoir level which is also called as a full reservoir level. Now we estimate the reservoir capacity by using the control maps at a dam site. So by using prismodal formula or by using say trapezoidal formula we can estimate the volume of water which is stored. So here you can find the contour one which matches with the highest level, this contour matches with this level, this contour matches with this level, so submerged areas at each and every level is calculated thereafter by using the formula one can estimate volume of water stored at each and every level. So one can find out these, now for calculating capacity of reservoir one can have control map then submerged areas calculated by means by measuring area of contour as each level, storage capacity of reservoir is estimated by using trapezoidal or prismodal formula and then one can draw the area capacity curves. So you can draw a curve elevation versus storage value in this way and here also this is elevation versus this is area submerged. So this gives elevation versus area submerged and this gives elevation versus volume stored. So one typical curve we have these curves are useful to estimate submerged area at different elevations and to estimate storage capacity of reservoir at different elevations and to fix up important reservoir levels accordingly once you have decided what should be dead storage, what should be live storage, what should be searcher storage. So here you will find a typical curve after surveys. So at 290 meter RL this is a curve so you have to come down and then you will find the storage capacity is say 1.7 kilometer cube. At 290 this area of submerged may be say here 100 square kilometers. But these curves go on changing due to sedimentation how it changes. So a typical change curves over a period of 1986 to 2011 are shown here. So summary we discuss important reservoir levels and different zones of reservoir and we also discussed by using area capacity curves how one can find storages and submergence areas and hence how one can fix up the reservoir levels. These are references thank you.