 Namaste and welcome back to the video course on watershed management. We were discussing about stormwater and flood management in module number H. So, in today's lecture, lecture number 34, we will discuss about flood control and management. So, some of the important topics covered in today's lecturing route, floods, causes, flood damages, flood forecasting and warning, flood control, reservoir operation, flood management and some of the key words for today's lecture include flooding, flood control and flood management. So, as we were discussing earlier, so stormwater and its management is a big issue. So, when we discuss about the watershed management, so we have to see that within the watershed, say how the rainfall runoff is taking place and then say how the flood routing or floor routing we have to do and then whether there is any scope for flooding in that area. So, all those issues we have to look into. So, in today's lecture, we are going to discuss say why this type of flooding can take place on a watershed basis or a particular area and then what are the causes and then what kind of control measures we can adopt in order to reduce this flooding. So, let us look into the flooding problems. So, as I mentioned earlier, so floods affects say a large number of people, say some estimate says that flood affects lives of more than 65 million people per year globally. So, you can see that that indicates how much is the the condo of problems say due to the flooding. So, more than any other type of disasters including water, drought, famine and other problems or including earthquake, we can see that this flood related problems or the the the death or other related issues related to flooding is much much more. So, that way we have to see that flooding say we have to accept it is a major problem and then we have to look into the these problems and then we have to look into the control measures. So, that we can reduce the problems of flooding. So, say for example, in east and south east Asia say during the monsoon season say generally this monsoon season will be say June to September, October. So, we can see that most of this rivers say in this regions South Asia and South East Asia, we can see that the the the river flow will be more than 10 times that of dry season flow. So, that way this river most of the river will be overflowing in many of the regions and then that creates a major flooding problems in many of these areas in South Asia and East Asia. So, it is estimated that. So, that way many of these countries have taken number of steps to reduce this flooding problems and even large number of dams were constructed in the past to reduce this flooding problem. An estimate says that about 13 percent of the 45000 large dams in the world these dams are built say for flood management function. So, in a 75 countries about 13 percent of the large 45000 dams these are only built to control the flooding problems in many of the areas. So, that way we can say we can look into that say what what kind of big problem is there due to flooding and then what kind of say losses like deaths and then economic losses all those things we can see and this is a major issue in many countries. So, now, let us look what are the the damages flood damages. So, we can see that there are number of damages related to the floods. So, it can be loss of death or loss of life the the injuries and then social disruption then say huge economic losses then say emergency course physical damage collapse of buildings structures bridges then roads all this say will be affected then many of the utilities like telecommunication systems and an electric supply all those will be affected then and say the cars and autos and other say automobiles will be affected. Then the major impact especially to crops. So, when due to the heavy flooding in many areas we can see that the crops will get spoiled and then say there will be related famine and other related issue. And then lost values of public agency services like now whenever say this kinds of flooding takes place we have to put into public agencies like a police fire force then hospital etc to to cope up with this kinds of flooding. So, that is another way say big damage or big loss due to the flooding and then also like loss like a tax losses property and sales all those things. So, that way we can see that flooding is a big problem and then in most of the countries flooding flooding takes place and then say we have to look into how we can reduce this flooding problems how we can control this flooding problems. So, that is what we will be discussing today. So, say whenever we discuss about floods generally most of the time this floods happens due to heavy rainfall that means say in country like India or South Asia it will be mainly due to the the the heavy monsoon which will be taking place from say 3 to 4 months starting from June to September or October of the year. So, that that is say one reason, but of course many other reasons are also there like in coastal urban cities as we discussed earlier also when heavy rainfall takes place simultaneously if tidal effects also takes place then the flooding problem increases. Similarly, then say the the say wherever especially hilly regions or wherever say snowfall is there when snow melts takes place then also there is possibility of flooding. So, let us look into the the different causes of flooding. So, as I as we discussed say flood can occur when a river exceeds its bank full stage and then water will subsequently inundate the adjacent surrounding area. So, generally say in most of the areas what happens is that say the the river will be overflowing and then the this water will be going to the surrounding areas and that inundate the adjacent surrounding areas. So, as as we were discussing. So, the floods can be due to heavy rainfall and like long periods of heavy rainfall will lead to an increase in surface or no an increase in river level. So, that is can be one reason and one most of time this is the main reason as far as flooding is concerned. Then snow melts. So, water in storage is often freed by spring mails increasing surface runoff. So, with the snow melts say the surface runoff increases and that can be also a cause of flooding and then say some of the causes like deforestation say if say as we were discussing in some of the earlier lectures whenever forest forest is say it store some portion of the the runoff. So, that the runoff will be slowly taking place. So, when deforestation takes place in a large scale then what happens is say the cutting down of trees leads to reduction in interception rates and an increase in surface or no. So, this may also lead to rapid erosion rates due to a lack of stability in the soil subsurface. So, that way this the some of the causes can be like deforestation and also like the in cost regions tidal effects and then in some locations due to any reasons any any any dam break takes place. So, that can be also a cause of flooding. And then of course, in say in urban areas whenever say urbanization takes place say due to say sudden say increase of urban say the the concrete surfaces or impermeable areas in cities then that may lead to an increase in surface runoff. So, as we were discussing in one of the earlier lectures. So, whenever the impervious areas increases then there will be as a time of concentration will be reduced and then there will be the peak will be increased. So, that way also especially in urban areas say and the urbanization can cause flooding. And then after urbanization the lack time is shortened peak flow is greatly increased and total runoff is cumbersome into a shorter time interval favorable condition for intense flooding. So, especially in urbanization the urbanization can also cause flooding. So, for say for example, some calculations says in a city that is totally served by storm drains and where 60 percent of the land surface is covered by roads and buildings. So, then floods are almost 6 times more numerous than before urbanization. So, if before urbanization if it is a rural area there is no impervious much impervious area then say compared to that say if 60 percent of the area is covered then there is say some estimate says there is possibility of 6 times more flooding in that kind of areas. Urbanization can be a major cause of flooding. So, that way say when we look into causes of flooding. So, say as we can see here say rivers are more liable to flooding say like due to various reason it can be heavy rainfalls, normal to all those things and then the banks overflows. So, and then as we discussed urbanization and deforestation and especially in coastal region the reasons can be also tidal effects. So, where the tidal also simultaneously rise and then also like say sometimes say failure of a dam all those thing can be some of the causes as far as flooding is concerned. So, on a watershed basis as we discussed the same if this is a watershed then say all the flow will be keep on coming as runoff from various sub catchments and then it will be say routed through the channel. So, that way then say when this level rises above the banks then flooding takes place. So, that way on a watershed basis we can say calculate or estimate how the how much flooding can take place through the some of the mathematical models which we discussed earlier. So, now say let us look what will be the results of this flooding. So, we have seen that the damages flood damage are much much big. So, it is not not only loss of life, but huge economical loss also taking place. So, let us look some of the important points what are results of flooding. So, due to flooding as we we can see that large amount of water will be flowing through the river. So, flooding greatly increases the rivers energy. So, it can do more work. So, that way the velocity of flow will be increasing the depth of flow will be increasing the deeper and faster flowing river can carry more load and more sediments will be carried and then also maybe say trees and all those things also garbage is etcetera will be also be carried through the river due to the increase in carrying capacity. So, most of us trend brown because of the large amount of sediments carried in suspension. So, due to during the heavy monsoon or heavy rainfall season the the the silt will be or sediment will be carried through the river. The amount of erosion carried out by hydraulic action and abrasion is greatly increased. So, due to the increase in velocity increase in depth. So, whatever the the the river the the flow conditions greatly increase and then the actions like hydraulic actions the velocity depth of flow all those things and then the abrasion. So, that the the the sides of the river may also get eroded. So, that will be also taking place. So, these are some of the important effects or the results of flooding. The amount of erosion carried out by hydraulic action is increased and then. So, how does this happen? So, as I mentioned when the velocity increases. So, the sides are not stable stable the river both sides are not stable or the bed level is not stable then all this soil will be carried say will be eroded with respect to the the movement of the water within the river. And then in the lowlands or the downstream side many features are formal during flooding like say say large kinds of deposition can take place and then. So, they are like oxbow legs and then the levees are there that will be affected or large amount of deposition takes place especially in delta regions or wherever the the the lowland regions. So, these are some of the important results of flooding say which which generally we can see say during especially during the monsoon season. So, now say when we look into the the damages caused by this flooding. So, we can say classify the damages into short term damages and the long term damages. So, short term means immediately say when flooding takes place immediately within say that time period or immediate time period what are the losses or what are the damages and long term means say what will be the repercussion economic repercussion or the infrastructure repercussion due to the flooding. So, flood damages we can classify into short term damages and the long term damages. So, short term damages like as we discussed it can be loss of life destruction of property crop damages loss of communication networks freshwater pollution loss of electric power. So, all those are some of the short term effects or damages due to the the flooding. So, these are immediately visible damages and then that these kinds of damages critically affect the the area and then say large kind of say say migration can take place due to these kinds of same short term effect and a long term effect or long term damages including replacing what is lost or damaged. So, when due to the heavy flooding say so much of infrastructure facility will be affected then so much area will be eroded and then crop will be affected and then electric power network or the communication network will be affected. So, now say after the flooding even is over we have to say replace what has happened since so that the people can start their normal life. So, that is the long term effect it is mainly economical loss huge economical loss huge infrastructure losses. So, governments how say how to get the funds to reveal the infrastructure say like roads, water treatments then say bridges then say electric power network like that. So, that is the especially long term damages we can measure in terms of economic terms. So, then also say due to heavy flooding say many of the agriculture land will be affected and then crop destruction takes place. So, once one crop is lost then you can see that food shortage will take place and that can lead to famine. So, that way flood damages can be short term or long term. So, that way this say when we discuss about the watershed management we have to see that how we can say control this flooding what kind of measures can be adopted so that to the flooding effect will be reduced and then with respect to the weather system say with respect to the weather prediction and then say the model like flood routing or say rainfall runoff modeling whether we can forecast say how say for the given rainfall condition or the for non rainfall condition how much a flooding is possible. So, flood forecasting is one of the important thing which we can look into. So, once we can forecast then we can also think about flood warning so that the people can be cautioned as this area be flooded. So, that you have to take appropriate measures to say take away your valuable things and then vacate the people from that flood affected possible flood affected area. So, that way flood forecasting is very important. So, for flood forecasting say generally it is a use of real time precipitation and stream flow data in rainfall runoff and stream flow routing models. So, we were discussing in the last some of the last few lectures say about this say rainfall runoff modeling stream flow routing. So, these are all say we can discuss some models we can directly utilize for flood forecasting. So, say so the forecasting is to say to identify how much the flow rates and then water levels for period ranging from few hours to day sacred depending upon the size of the watershed or the river basin. So, depending upon the location depending upon the watershed or river basin scale and then depending upon the precipitation pattern say sometimes the rainfall takes place for a few days or say few hours. So, depending upon that say we may have to go for short term flood forecasting or long term flood forecasting and then also we may have to say calculate for the given rainfall condition how much is the runoff and then corresponding stream flow and then its routing. So, all these are very important as far as flood forecasting is concerned. So, flood forecasting and also make use of forecasts of precipitation to extend the lead time available. So, say in for forecasting we have to also identify the rainfall pattern which is going to come say. Now, personally if heavy rainfall takes place and next few days how the rainfall is going to take place of precipitation is going to take place. So, this forecasting is also required since there will be some lead time available. So, so that we can predict say from one rainfall even to how another rainfall even say what will be the effect as far as flooding is concerned. So, that when the forecasting system may account for like other than the precipitation we may have to account for the snow melch say if the area snow in some of the areas where snow is there then what is the possibility of snow melch then flood plains and wash lands. So, how the flood plains will be affected then flood defences including control gates. So, if the reservoirs say if you have go to some control gates or a tidal gates where the tides will be entering from the the the the x-rays to the river. So, that kind of gates how we can control then tidal effects near the sea and sea surges all those things we may have to account for. So, flood forecasting is not only a simply the the rainfall runoff forecasting or the the rainfall forecasting and then corresponding runoff evaluation, but we may have to also deal with the various other phenomenon like a snow melch and then say the control gates operational control gates and then the tidal effects sea surges like that. So, that way all these things we have to account as far as flood forecasting is concerned. So, that way if we can forecast say for the given say weather prediction system say for few days or few hours. So, accordingly if we can identify the rainfall pattern or the rainfall intensity and from that we can identify say the runoff or the flood depth variations or the discharge variation and then say depending upon the area depending upon if we can identify the possible areas of flooding and then we can prepare a flood warning maps and then that can be transmitted to the public. So, that the administration and public can take appropriate measures. So, that way for forecasting and warning is a very important. So, flood forecasting through say range of adrodynamic snow melt or flood routing models. So, through these models only we go for flood forecasting that way flood forecasting is an important component of flood warning system. So, the distinction between the flood forecasting and warning is that the outcome of the flood forecasting is set of forecast time profiles of channel flows or river levels at various locations. So, say when we do this kinds of say rainfall runoff modeling or flood routing. So, we can identify say with respect to time which of the area will be affected then the water levels how it will be varying in the channels or rivers and then at various location how the the water will spreads. So, like that. So, that way the flood warning is the task of making use of this forecast to make decisions about whether warnings of floods should be issued to the general public or whether previous warning should be rescinded or retracted. So, that way say whether we have to go for flood warning say depending upon the rainfall condition depending upon the river level conditions or channel level conditions we can decide whether we have to give a warning and if already some warnings are given whether that is going to continue. So, that if it is not going to continue we can retract back or rescind. So, that say yes the possibility of flood warning is flood is not there. So, that people can start their normal way of life. So, that way flood forecasting and flood warning are very important aspects as far as flood management is concerned either on a watershed basis or on a river basin scale. So, now within this perspective we are discussing about the flooding flooding the damages due to flooding then causes of flooding and then flood forecasting and warning. So, now let us look what kind of control measures we can adopt. So, that the effect of floods can be reduced. So, generally say the flood control measures can be two varieties one is structural type of flood control measures and second one is non structural type of say flood control measures. So, when we look into structural say measures actually what we are doing is say what we are doing is say if we identify some areas where flooding problem is there then we construct certain structures or various measures. So, that say the flooding will not takes place or flooding effect will be reduced in that area. So, that way there can be number of structural measures which we can adopt depending upon the location area then the river flow condition and the geographical conditions. And as far as non structural measures are there say we are not doing any these kinds of construction activities. So, these kinds of things, but say we can say for example, we can go for flood sowning map. So, that people will be careful while making a building in particular location wherever the flood sowns are there. So, now let us look into the details of the structural measures. So, many structures can be constructed especially on river sides or river banks. So, that the area the flood prone area can be protected. So, some of the things which we can do are listed here. So, like you first one is levees. So, these levees are embankments constructed parallel to the course of stream to prevent inundation of large areas. So, that way say they want the sides of the both sides of the river. So, parallel to the to the bank. So, we construct say the retaining walls or the say some embankment kind of structures. So, that the river banks will be raised. So, the whenever the water level rises it cannot spill over to the surrounding land. So, and then we can protect the area. So, levees are generally used to say reduce the flooding problems wherever flood prone especially flood prone rivers. So, some of the important design consideration while designing levees include say location of the area say then slope of the slope stability of the river banks. Then the possibility of seepage then interior drainage coming to the the areas then top width and freeboard how much freeboard should be given then what are the possibility of erosion and then score protection. So, all these are some of the important issues what we will be looking into when we go for the design of levees. Then another kind of structural structure which we can make is called a groins. So, these are dives extending from the bank of river so it will be going say the perpendicular to some through some angle to the bank of the river and generally these structures are made to protect the river banks. So, that the bank will not be eroded and then further the the flooding problem will not take place. So, that these kinds of structures are called groins and then sometimes we can construct cut-offs. So, cut-offs are artificial excavated cut-offs to strengthen the channel. So, straighten the channel not strengthen straighten the channel. So, say some some the the channel or rivers may be meandering and then it will be going say in a very irregular way and then when heavy flow or heavy flooding takes place say in this irregular shape say the water before try to flow directly on a straight line and then the river will be affected. So, that way before such a flooding possibilities we can straighten the channel. So, through appropriate cut-off say by considering the meandering nature of the of the channel. So, that kind of structure is called cut-off and then say we can also have some structures like flood bypass. So, this bypass means say wherever a possibility of same heavy flood say in some regions. So, we can say take the flow coming through certain other means like tunnels or the pipes or through some other channels and then we can divert the flood flow. So, flood bypass means we are diverting a portion of the flood flow. So, that the area will be saved especially in city regions say if the chronic flood problems are there then we can construct a flood bypasses. Then some of the other structural measures include channelization. So, channelization means say some of the activities what we can do we we can clear the channel then we can straighten it then we can widen it then we can deepen it and also then the the sides can be lined. So, that we this process we can conveniently put it as a channelization. So, this will increase the flood carrying capacity of the river or the channel. So, that way the flooding problem will be reduced. And then say if any bridges especially between the the bridge piers the flow conditions say sufficient flow cannot pass then that kind of bridges we can modify by giving appropriate height or appropriate ducts and then so that the normal flow will be taking place. So, bridge modification is another structural measures like removal replacement or widening and raising as far as bridges can sense. Then say like a flood proofing. So, flood proofing means flood plain or flood hazard sounds by ring levees or flood walls. So, we can construct flood walls say especially cities we can do flood proofing by constructing say walls or levees and then the area can be protected. Then say also depending upon the area we can have say sufficient areas available we can have a retention ponds or retention basins where say some other rain water will be stored for some time and then that will be released gradually once the rainfall is or the flood problem is residual. So, that way the retention basins are small environments designed to temporarily store storm runoff and this storm runoff will be released gradually. So, that way these are some of the important structural measures. So, that means we are going to for some way or another way of construction or some modification to the existing system. So, that the flooding the flood prone area will be protected or flood problem will be reduced. So, these are some of the important structural measures which we can adopt as far as flood control measures are concerned. So, now let us look into some of the non-structural measures. So, these non-structural measures say we can do many things. So, some of the important things are listed here. So, we can establish regulatory flood plains. So, depending upon the river flow we can we can study the historical the flooding problems or the flood levels or the depth of flow taking place in particular location especially in city regions and then say we can have some rules and regulations. So, that no construction will takes place in the flood plains. So, that the property and the human life can be saved. So, that way we can establish regulatory flood plains and then storm water regulations. So, storm water whether as we discussed whether we can store some of the water or we can go for water harvesting or we can that way through a forestation all those measures which we discussed earlier also we can reduce the intensity of the storm water movement and then that kind of regulations we can have. So, storm water regulations are another flood control non-structural flood control measures and then also we can have flooding zones or flood zones. So, for the given for the given river according to the given conditions after studying the the rainfall to run off or the flooding problems for large number of years like 10 years 50 years. So, 100 years then we can generate flood zone map. So, that we can say restrict the development in that flood zone areas. So, flood zone mapping is is one of the generally used technique as far as a non-structural measures is concerned. Then also as we discussed earlier we can go for various watershed managing plants like rainwater harvesting then water conservation measures within the area. So, all those things will give us some effect as far as flood control is concerned. Then flood emergency planning. So, if the flood is going to take place or if there is possibility of flooding we can create emergency plans say nowadays many of the states and and at a central level in India we have got a national disaster management authority. So, this disaster management authority also deals with the flooding. So, they will come up with certain guidelines. So, which way each authority or each state and each district has to follow. So, that way we can have flood emergency planning and then wherever say the the flood prone areas say if there is any say some areas we can identify that is flood prone then we can relocate the people and the whatever the that location. And then of course, say another important measures we can say to save the economic losses we can go for flood insurance. So, that is another measures which we can adopt. So, this is actually flood insurance say various insurance companies provide this flood insurance, but this this base generally based upon flood risk assessment or flood risk zones of the area which we consider. And then of course, another important non-structural measures is flood appropriate flood forecasting and warning. So, that the people can take or the public can take appropriate measures so to protect themselves and their properties. So, this way so that way we can see that the flood control measures are concerned it can be either structural measures or non-structural measures. So, now let us look into say how we can control this flood or say let us look some of the important aspects which we can do to manage the flood or flood control management. So, some of the important ways through which we can manage the flood are listed here. So, this actually reduce the intensity of flooding and then ultimately it may also say it may keep away the possibility of flooding. So, some of the important things can be done are listed here like afforestation. So, we can plant trees that may increase the interception rates and then that may reduce the surface runoff. So, this is can be one managerial measures measure. Then second one is dams and reservoir. So, depending upon the areas as I mentioned earlier say about 13 percent of the world largest dams are concerned only for the flood protection or flood control management. So, that way dams and reservoirs. So, this hold back and regulate the flow of river water and this can be used as a fresh water supply and also generation of hydroelectric power. So, that way dams and reservoirs and then diversion channels and basins. So, wherever flood porn areas are there we can divert with the some of the flood water through some other extra channels pipes or tunnels. So, overflow channels which takes surplus water out of a river in times of flooding. Then channel straightening and dredging as we already mentioned. So, this may smoothens the channels to increase the speed I mean velocity of the river and get water out of the drainage basin as quickly as possible. So, that way the intensity of flood will be reduced or the flood depth will be reduced. Then some of the other measures say like either it can be structural measures for flood control management like artificial levees. So, we can say construct levees on river banks. So, that more water will be hold in the river then we can have culverts. So, semi circular smooth channels increases velocity and gets water away from the urban areas as quickly as possible. Then revetment channel walls or gabions. So, these are some of the measures which we can adopt. So, like strengthen the river banks from erosion using large lumps of stones then say we can have gabions or walls. Then restricted use of flood plains. So, as we discussed so this is a non-structural measure. So, we can have legislation so that higher selective so that there will not be any construction in the restricted flood plain areas. Then higher selective insurance premiums or refusal to insure particular locations. So, all these can be used. And then finally, coordinated flood warning system. So, this is one of the bottom thing which can be done as flood control management. So, this coordinated flood forecasting and flood warning and emergency reaction procedures we can have. So, that some specified agencies for example, environment agency in United Kingdom say environment protection agency in USA or national disaster management authority in India. So, these kinds of agencies can coordinate the flood forecasting and flood warning. So, that the people will be say the people can be warned that there is a possibility of flooding and then appropriate measures can be taken. So, that way flood control management is very important. So, earlier we were discussing that say some of the dams constructed say about 30 or 15 percent of the larger dams are mainly constructed for flood management or flood control. So, that way the reservoirs are performed by this the dams. So, we if we operate appropriately many of these reservoirs say we can control flood very effectively. So, that way reservoir operation with respect to the say especially in monsoon season or flood rainfall season that is very important. So, let us look some of the important aspects of flood control and reservoir operation. So, dams and reservoirs have helped immensely in attaining cell sufficiency in food grain production besides flood control and drought mitigation. So, that we have seen earlier. So, that way this reservoir store a large amount of water and that the that will say reduce the intensity of flooding or the flow condition that can takes place within a river. So, flood depth in rivers depends on reservoir releases or reservoir storages. So, a reservoir is a depository for the storage of water up to a maximum limit. So, there will be maximum water level possibility within the reservoir. So, depending upon the the the rainfall condition depending upon the runoff condition we can manage this level so that appropriate flood controlling is possible. And then since spilling water implies passage through a critical hydraulic section a dynamic storage volume can be filled up only during spills. So, we have to appropriately manage say during the rainfall season how much spills should be allowed and how much should be stored. So, that we can have effective flood control through appropriate reservoir operation. So, operational pool say it is the it is defined as the volume between the minimum level at which controlled releases can be made and maximum static full pool. So, actually this this the difference between this minimum level and maximum static full pool is generally utilized for storage and that can be effectively operated so that the the say if the possibility of flooding that can be reduced. So, that way reservoir operation is very important. So, now operational pool is conceptually divided into conservation and flood control pools. So, we we were discussing about this operational pool in the last slide. So, this can be conceptually divided into conservation and flood control pools. So, consideration means how much water should be conserved for future purposes and then flood control pools to reduce the flood how how much effectively we have to store. So, maximum possible empty space is desirable for flood control especially in monsoon season we have to keep maximum possible empty space. Then while water storage is required for the remaining objectives of the say like water supply irrigation hydropower especially if the reservoir is for multi purposes other than flood control. So, we have to see that sufficient water is available for future water supply irrigation hydropower generation etcetera. So, since flood risk differs according to the season the flood control pool typically varies according to the time of the year. So, as I mentioned during the monsoon season same heavy rainfall season we have more flooding problems. So, that way we should govern the operational pool which is for the flood control. So, that way we have to control. So, the reservoirs can be single reservoir say where we can have direct control only one reservoir how much is to be released or how much is to be stored. So, that flooding will be reduced. So, like that we can easily take decision, but wherever possible if there are multiple reservoirs or a system reservoirs. So, this always will be advantageous as far as flood control is concerned since whatever extra flood is coming will be stored in a cascade of reservoirs. So, a cascade of reservoir is more effective in terms of peak delay than the equivalent storage capacity combined in one reservoir. So, if multiple reservoirs are there. So, we can effectively operate the reservoir in such a way that say good storage can be also given and good say release will be appropriately done from the each reservoir. So, that flood will be controlled and then also say appropriate storage will be given to each reservoir. So, now say when we say look into say some other reservoir which is only constructed for flood management. So, which are called flood reservoir flood reservoirs. So, how to manage this. So, the flood control management approach say we can specifically develop for that particular reservoir. So, considering the flood pool as a restriction for the optimization or simulation of the conservation pool. So, we have to we may have to go for simulation with respect to identify how with respect to rainfall to runoff and how much flow is taking place to the reservoir and then how to say whether how much storage should be allowed. Then operation under flood conditions can be performed through previously set rule curves or within a real time framework. So, we can have real time reservoir management for flood control or we can also develop a rule curve depending upon the past experiences, past data, we can generate root curve and using this rule curve we can operate the reservoir for flood management. So, but of course it is always better to go for real time management. So, that either rainfall variation or of the of the with respect to weather condition we can have say real time flood control. So, the second approach is uses a very much real time information I mean the real time framework information as possible from the whole system as well as it is near future. So, it is not only current system, but for the coming few days or few weeks also how to operate the reservoir for flood management. So, all these issues will be considered. So, we can have a decision system which can be closely related to the real time operational forecasting and warning availability. So, if the if the for particular area if you are having the flood forecasting and flood warning system. So, by considering this we can operate the flood reservoir and then we can take appropriate decision how much storage should be given how much release should be given. So, that finally, by considering all those things we can have a real time flood management. So, then we can develop a real time flood management. So, in this cases say so, to reduce the the silting problem in the reservoirs we also have to deal with the sediment related problems. So, that will be also considered as far as flood reservoir management. So, that the capacity of the of the reservoir will be maintained. So, now so, we were discussing about the flood control management. So, let us look into what are the important risks associated with say flood and flood control. So, some of the important risks I have listed here. So, floods have say occurred throughout the time and are not necessarily damaging. So, sometimes say severe flood can have say severe damages, but some minor floods there may not be much damage. So, early legislation authorized flood control in response to devastating losses. So, depending upon the depending upon the location we can have legislation and then we can have appropriate flood control system. Then we cannot rely we cannot really control floods, but we can modify water flows in space and time. So, this as we discussed the flood flooding situation depends upon many parameters like meteorological parameters, geographic parameters or like conditions like earthquake or the dam break. So, so many parameters will be there. So, we cannot control all these parameters. So, that way complete control of the flood is not possible. So, only thing is that we can modify the problem or we can reduce the effect in with respect to space and time. So, say generally in say in countries like America, say US Army Cops of Engineers they take their mission is to assist with an provided leadership in managing the flood risk. So, depending upon the agencies working in that particular country whether it is Army or disaster management cell, whatever the agency. So, they can take the leadership for control of flood or to reduce the flood problem. So, this includes making the government investment for reducing damages from flood. So, like what kind of measures to be adopted in future and then what kind of disaster management measures to be adopted. So, that way complete description of a plan that can include all structural, non-structural, legal and institutional features both proposed and existing that contribute to indebted flood control outputs. So, that way we can come up with flood risk management measures for the given area for the given location and depending upon the various parameters for that for the particular agency which is dealing they can take the leadership and then come up with appropriate measures as far as flood risk management is concerned. So, some of the important strategic goals when we discuss the flood risk management. So, these are distilled here. So, first one is provide current accurate flood plain information to the public and decision makers. So, this is very important. So, accordingly the decision makers can take decision and the public can react. So, then second strategic goal is identify and assess flood hazards posed by aging flood damage reduction in infrastructure. So, this we can assess and then take appropriate measures. Then third one is improve public awareness and comprehension of flood risk. So, this public information or public awareness very important. So, that the people can react with sufficient time is given and then they can take appropriate measures themselves and then government can give appropriate support. So, that way we can improve the public awareness. Then integrate flood damage and flood hazard reduction programs across say local government, state government or federal agencies. So, we can come up with integrate flood damage and flood hazard reduction. Then improve capabilities to collaboratively deliver and sustain flood damage reduction and flood hazard mitigation services to the nation. So, this has some of the important strategic goals which we can adopt as far as flood risk management is concerned. So, then if you look into this this charge. So, there will be say initially high risk will be there then depending upon the activities given in that particular area we can see that the risk will be reducing. So, first one is like insurance, then building courts, then zoning, flood zoning, then levees, then condensate response plans, outreach. Then there will be the risk will be considerably we can reduce through various plans as shown here. So, then say what are the uncertainties associated with the flooding problems or flood risk management is concerned. So, in flood damage reduction planning uncertainties include like in future hydrologic events. So, whether the rainfall is going to continue or when the next high say high intensity even can take place. Then stream flow and rainfall, then choice of distribution and values of parameters. Then simplified models of complex hydraulic phenomena like geometric data, the misalignment of structures, material very very team and slope and reference factors etcetera. Then relationship between depth and inundation damage. So, say we can identify this depth and inundation damage relationship. So, through structural values and locations and how the public will respond to a flood. Then structural and geo-technical performance when subjected to floods. So, what are the structural related issues for the various structures like bridges, buildings etcetera and then what are the foundation related problems like that. So, now when we discuss about the flood problem and then we have to look into what are the restoration measures which we can adopt. So, this we can have it in say in about 5 steps. So, first one is we have to prepare plans appropriate plans. So, that is in anticipation say flood measures plans we have to develop. So, that is the before the event returns. Then we can go for say detection like through warning a flood warning or say forecasting and warning. So, like detection ongoing information through that we can gather and provide a warning to monitor prevention and mitigation systems. And third one what kind of preparation we can do. So, that once flood warning is put of say we can communicate with the people, we can communicate and take appropriate evacuation measures. Then say what will be the once the flooding starts or flooding takes place, what will be the first response. So, like actually what is happening first response. So, that is once the event has occurred the negative consequences how we can minimize it and then what kind of action can be taken to save lives. Then how we can give say like provide food shelters and clothing to the survivors. So, that the appropriate same response can be there. Then once the flood is receded, then what we have to look into is say how we can compensate for the people or how we can reconstruct say what was say destroyed say like rebuilding restoration. So, this way we can go through an appropriate say cycle as far as flood problem and restoration is concerned. So, now before closing for today. So, let us look some of the important aspects what are the flooding problems in India and then say how what kind of measures are taken to reduce this flooding. So, as I mentioned earlier say in India also flooding occurs in almost all rivers then say the reasons are some of the common reason which we discussed earlier like heavy rainfall, inadequate capacity of rivers, then inadequate drainage network and then sometimes heavy rainfall or climate change effects. So, these are all causes the floods in India. Then in north end India especially wherever Himalayan regions ice jams or landslides blocking the streams, then eastern regions like typhoons and cyclones these are all causes the floods in as far as India is concerned. Then excessive rainfall combined with inadequate carrying capacity of streams resulting in overspilling of banks is the main cause of flooding in majority of the cases in India. So, then if we look into the one say an assessment by Ministry of Water Resources. So, we can see that about 35 million hectares of the land is same liable to floods. So, this is about say more than 10 percent of the of the land. So, say here say as per Ministry of Water Resources website. So, it is given state wise how much area is liable to floods say for example, Andhra Pradesh 1.39 million hectares. So, like that state wise this distribution is given which the area which are liable to floods. So, as we were discussing. So, we cannot control the flood totally, but what kind of measures can be taken say like structural measures or non-structural measures to reduce the effect of flood. So, flood being a natural phenomena, total elimination is not possible. So, so that we have to look into flood management which aims at providing reasonable protection against damage at a reasonable economic cause. So, this is a flood hazard map as far as India is concerned. So, wherever this red say color is there, these are some of the areas highly vulnerable to floods. So, especially in the Himalayan regions Himalayan rivers like Ganges, Brahmaputra river and then Mahanadi river basins like that due to various causes as we discussed. Then say in India the systematic planning for flood management commenced with the launching of national programs say early in 1954. So, last 56 years government of India and many other state governments are doing many measures to reduce the flood hazards. So, during the last 58 years different methods of flood protection structural as well as non-structural have been implemented in different states. Structural measures like storage reservoirs, flood embankments, drainage channels and erosion parks. Then channel improvement was detention basins etcetera were undertaken on large scale wherever flood prone areas are there. And then non-structural measures like flood forecasting, flood plains warning, flood proofing, disaster preparedness all were implemented or a large number of agencies were say established in the last 2-3 decades. So, now we are having appropriate flood forecasting warning system based upon the forecast by Indian material department and then the satellite data which is provided by Indian space research organization. So, like that now say number of non-structural measures are also undertaken. So, as per the Ministry of Water Resources website say in some of the various flood managing measures undertaken say last few decades include flood embankments about 3500 kilometer, sorry 35000 kilometer flood embankments were constructed. Then drainage channels for 51 317 kilometer then towns protection works about 2400 numbers done and villages raised say so that it will be protected from the floods. So, it is about 4700. Then say reservoirs are constructed with exclusive flood control storage as we discussed earlier some of the reservoirs like Maithan, Panjet, then Konar in Damodar valleys, then Chandil Dam on Subarna Reha and Rangali Dam in Bramini river. So, these are mainly constructed for flood control measures. Then last 6 decades a large number of dams were constructed so that the life storage of 171 billion cubic meter created so far in the various reservoirs for irrigation, hydropower generation, drinking water etc. So, these also help indirectly in reducing the flood intensity by storing part of the flood waters in them. So, these are some of the measures taken by government of India and various state governments. So, as far as flood hazards is concerned the flood management measures undertaken so far has provided reasonable degree of protection to an area say about 16.5 million hectares throughout the country. So, area benefited is distilled here then length of embankment is about 34397 kilometer then length of drainage channel then town village protected so as we discussed earlier. So, these are some of the effects of this flood and in protection measures adopted by government of India and other state governments. So, then also we are having an effective flood forecasting system. So, this has been recognized as one of the most important aspects reliable and cost effective. Then recognizing the crucial role it can place under water commission ministry of water resource has set up a network of forecasting station throughout the country covering all important flood prone areas. Then the forecast issued by these stations are used to alert the public and enable the administration and other agencies so that appropriate measures can be taken. So, these are all done in collaboration or in coordination with the India Space Research Organization, Indian Meteorological Department and various telecommunication network. So, that appropriate warnings will be given. So, as far as national response mechanism for as far as flood is concerned. So, first you are saying the apex bodies union cabinet and under union cabinet national crisis management committees is like a national disaster management committees are there related to floods and then agriculture ministry then ministry of water resource ministry of environment and its secretaries they are all coming together as far as this apex bodies consent. And then various states relief commissioners are there then central relief commission will be reporting say they will be state relief commission will be reporting to central relief commissioners and then agencies like Indian Meteorological Department, Central Water Commission and other departments all come together. So, that way there is say we are having a crisis management group and a national disaster management authority. So, this authority looks after say what kind of mechanism to be done or what kind of response should be done for the given flooding problem. Say for example, say in Andhra Pradesh cyclone hazard mitigation project say last few years this has been undertaken. And then like hazard mitigation studies were done then Indian Meteorological Department early warning capacity through doppler radar were implemented the infrastructure creation and restoration then flood drains and embankment studies were done appropriate measures were taken then road restoration storm shelters. So, like say what kind of things can be done. So, appropriate studies through appropriate studies this can be done. So, finally to conclude flooding is a major problem. So, we have to recognize the linkage between the natural hazard like flood and then development or urbanization effects and connecting the development programs to disaster management that is very essential. Then forecasting and warning system appropriate forecasting warning systems are very essential then we have to go for contingency planning like food grain availability preparedness adaptive capacity by creating management systems like that. So, appropriate authority and appropriate system should be made. So, that flood management is possible in an appropriate way. So, these are some of the important references used for today's lecture. So, before crossing few questions one is tutorial questions so critically study the flooding problems in India what are the measures taken by government of India and other state governments to reduce flood impacts how we can have better flood control measures on watershed or river basin scale. So, few self evaluation questions describe flood and related problems this illustrate short term and long term flood damages discuss various flood control measures differentiate between structural and non-structural measures illustrate flood control and reservoir operations. Few assignment questions what are the important causes of floods discuss flood forecasting and warning what are the important ways of flood control management and discuss the flood risk management and related issues. So, these are some of the questions which are related to today's lecture. So, by going through this lecture you can easily answer these questions. So, what we are discussing is say flood control and its management. So, under the storm water management this module number 8 we were discussing the flood control and management. So, with this module is over further we will be looking to drought management issues related to watershed management in the next module. Thank you.