 Student Professor Department of Civil Engineering from Valchian Institute of Technology, Sholapur. In today's session we are going to discuss a topic rainwater harvesting which is a part of basic civil engineering. The learning outcomes at the end of this session students will be able to explain the method of rainwater harvesting system. Now before going to rainwater harvesting system we should understand what is water management. Water management is an activity of planning, developing, distributing and managing the optimum use of water resources under defined water policies and regulations. As we know our population is going to be increased day by day and the supply of water is short as compared to the demand of water. So to provide water for the purpose of domestic as well as industrial purpose we should use the concept of water management. So in that water management we have the policy regarding distribution of water from the given resources. So a part of water management we are going to understand what do you mean by rainwater harvesting. So rainwater harvesting is also a part of water management. Rainwater harvesting is a technique of collection and storage of rainwater into natural reservoirs or tanks or the infiltration of surface water into subsurface aquifers. So in rainwater harvesting system we are going to collect the water during rainfall and it is going to be utilized for future purpose. Now what is the necessity of rainwater harvesting system? As we know for the cultivation of land we required water and the source of water is rain that is the main source of water and also the rainfall in our country is uncertain and unpredictable. So we should conserve the water for that we have to imply or we have to implement this rainwater harvesting system. Now it is a typical sketch of this is a typical sketch of rainwater harvesting system. In this sketch we can see from the rooftop the water is going to be collected during the rainfall and it is collected in a terrace. And from that terrace it is going to be collected by means of this downtake pipe to the storage tank. So before passing through storage tank it should get filtered. So proper filter media will be there to remove the impurities. Similarly after filling this storage tank the excess water is going to be collected by means of downtake pipe and is going to be recharged to the poor well for increasing the high water table position or increasing the water table, ground water table position. So this also done through filter media. Now let us see advantages of rainwater harvesting system. It provides self-sufficiency to water supply. It reduces the cost for pumping of ground water because the water level is going to be increased so the cost of pumping is going to be decreased. Also it provides high quality water soft and having low minerals as we are going to remove the impurities by using the filter media. So the quality of water is also good. It improves the quality of ground water through dilution when recharged to ground water. Then while recharging the water to ground so we are going to filter it so the impurities is going to be reduced. The advantages of rainwater harvesting system is that it reduces the erosion of soil in urban areas. Also the roof top rainwater harvesting is less expensive. The cost required is very less. Rainwater harvesting system are simple which can be adopted by individuals. Roof top rainwater harvesting systems are easy to construct, operate and maintain. Now it is compulsory for all people to adopt rainwater harvesting system. Nowadays rainwater harvesting system is compulsory. In case of healy terrains rainwater harvesting is preferred because the water is going to be collected by a gravity and this implementation of rainwater harvesting is very easy. In saline or coastal areas rainwater provides good quality water and when recharged to ground water it reduces salinity and also helps in maintaining balance between the fresh saline water interface. In islands due to limited extent of fresh water aquifers rainwater harvesting is the most preferred source of water for domestic use. Nowadays it is compulsory for everybody to implement rainwater harvesting system. In desert where rainfall is low rainwater harvesting has been providing relief to people. So in case of Rajasthan in the state of Rajasthan this rainwater harvesting system is very popular method. Now there are some methods of rainwater harvesting. First one is storing rainwater for direct use, recharging ground water aquifers from roofed off runoff, recharging ground water aquifers with runoff from ground area. Now this is a sketch which shows how the rainwater is going to be stored for direct use. Now as the rainfall is happened this water is going to be collected through this down take pipe and it is passing through the filter bed. Now filter bed consists of charcoal, sand, gravel, particles and through this filter the water is going to be passed and it is going to be stored in the tank. So during this process the input is going to be reduced. Now the second thing is that recharging the ground water aquifers from roofed off runoff. So here water the water is collected from the top of the roof that is going to be collected through down take pipe and it is passing through filtration tank where the input is going to be removed and then it is passing through the connection pipe to the ground water. So this recharge of ground water is taking place. Another method is recharging ground water aquifers with runoff from ground area. So water water is going to flow through the surface on the ground. It is going to be collected by gravity and it is passing through the filter media and then it is entered into the well and hence it recharge the ground water. Now you are supposed to pause the video and answer these questions. Now these are the answers. As we know the rainwater harvesting technique helps to recharge ground water. So this statement is true and second question is capturing runoff from roof tops is also called rooftop harvesting. So the first option is correct. Now these are the references which we are using for creating the video. Thank you.