 system and I had given you this equation for this was the equation which we had written of application or the unit stream size and I had used an efficiency which I had called application efficiency. The way we have defined our application efficiency if we recall we are defining the application efficiency as two components one is the application efficiency and the other is the distribution pattern efficiency. So in our case because there is lot of overlap in these areas we had defined an application efficiency which was volume delivered to the application surface to move water to application device that is how we had defined our application efficiency remember that and along with this we had defined another efficiency though this is multiplied by 100 there is another efficiency which was the distribution pattern efficiency so EDM we were calling as distribution pattern efficiency and that was volume of water stored the combination of these two we said will give you the application efficiency as is normally defined is not that. So in this we will rather than using just EA we can either say is a combination of EA and ED specifically in this particular situation is assumed that EA is defined here, EA is 100 percent that means there is no loss when you are supplying the water from the device onto the application surface so we are assuming that there is no loss in real application because this is a generic purpose definition which is also used in the context of sprinkler system where you might be losing some water when the water comes out of the sprinkler head or the sprinkler nozzle and is applied onto the surface of the field the application surface. When this particular situation when you are using the irrigation methods you might find that this can be easily taken as 100 percent okay so your application efficiency is basically confined to the ED value so instead of using EA as we had used in the last class I think we will better either use the combination of these two or if we assume that EA is 100 percent as per this definition we will just use ED which will give you the distribution pattern efficiency which will give you an idea that how much of the water is at least stored in the root zone in comparison to what has been delivered okay. This efficiency ED what is the level of efficiency which should be used when you are designing a system you have to have some available values from the experimentation from the actual data available and that is available in the form of some tables and one such table is available which I will make available to you during the course of your the notes or the sport material which I am preparing for you but I will just you give you the suggested design application efficiency of the design distribution that the pattern efficiency which we have just defined. This ED value is given for different intake families and we had discussed what the intake families are so for different intake families there are relationships available where you have for different slopes and the slopes are given in meters per meter for different slopes and for different intake families let us say that these are the ranges of the intake families which will in turn suggest what is the type of soil which you are using so intake family will be basically the this value is a function of what type of soil you are using and it will also depend on along with the intake family how much is the depth of application okay and the depth of application they are these are the various possible depth which are frequently in use 25 millimetres this will be in millimetres, 25 millimetres, 50 millimetres, 70 millimetres, 100 millimetres in some cases you might have 125 millimetres also these are the most common depth which are prevalent in actual use. So dependent on what is the intake family what is the value of slope variation again there are varying slopes which might be the range can be quite large and so on you might go up to 6 percent, there is 6 percent here we are using it in meters per meter so in terms of percentage this will be 6 percent this will be 0.05 percent. For these slopes for a specific value of application and for specific value of the intake family there are some recommended efficiencies which are the design efficiencies which are achievable efficiencies those efficiencies can be used to find out the unit stream size. I will give you an idea about for the case of family of 1.5 values of tough application of this range just to give you an idea what can be the possible variations of these efficiencies for the slope is again 75, 85, 80 percent, 80 percent, 80 percent let us look at the last slope here 50 percent, 55 percent, 50 percent. So this is the variation I have just picked up some values from the recommended values of the table you will find that let us serve some values in this category also for 0.3 intake family what is the order of magnitude of you will find that in general when the slopes are flatter you can get the higher values of efficiencies when the slopes increase in some cases it might not be feasible anymore to have under specific intake family you might not be able to use a slope beyond that specific slope for example in this case 50 percent efficiency is achievable when you have a slope of 0.5 percent the depth to be applied is 25 millimeters okay you might not be able to get a efficiency which is even 50 percent if you try to apply a depth which is more than very 5 millimeters with such a slope and with such a family of the soil. So there are some recommended efficiencies or the efficiencies which have been seen to be achievable through the experimentation those values have been they have been recommended here you can use them for your design purpose okay. In general you will find that higher efficiencies can be achieved for moderate soils which have moderate intake even the higher values of these intake family numbers will suggest that the efficiencies will load on but in this range somewhere from 1.5 to 3 intake families you will have quite reasonably good intake the efficiencies which are achieved but as you increase the slope these will be duration of those achievable efficiencies okay. Having selected an appropriate value of ED you can substitute that in the value of the relationship of the unit stream size and get a value which can be used for your specific conditions. Suppose you have you have found out the discharge you have adopted some value of the length of the border you have also picked up values like how much depth of irrigation is required that is again known that is a function of what is the requirement from your the design will also involve in checking these parameters checking these values whether these values are in within the permissible range so you should also look at design limitations and these limitations are in the form of checks so once you have come out with the design once you have selected some parameters you must check those parameters with respect to the various criteria and these checks you can check the inflow rates and check the depth of flow. The slope had mentioned that there can be different possibilities you might have some things which are fixed in your conditions so you can check those items whether they are within the restricted ranges or they are not within the restricted ranges once you have checked those things and you have satisfied your design parameters basically what you are checking for is one major thing is that you should should not have any erosion problems they are very detrimental for your total irrigation process and there are some other conditions which you will see subsequently as we go further so let us try to look at these items let us try to check our designs let us try to look into the relationship which are available for these these checks which we have just looked at what is the maximum in some cases these relationships are based on the hydraulic equations in some cases there are some empirical relationships also which are put forward and they have been obtained from the actual experimentation. So to find out what is the maximum unit rate which is permissible and this is basically from the point of view of the non-erosive nature of this stream what is the stream size under the specific conditions which can remain non-erosive that is what we are trying to look at because the stream size which you have found out you can check that stream size against this and this relationship is given for under two conditions this is basically we are trying to locate from the point of view of non-erosive and the two conditions in terms of what type of crops you are having the first variety of crops are those crops which are non-sword forming which include the alpha-alpha or small grain crops which are basically which are not resistance their root system is not very well formed so all those crops if you encounter those crops then your maximum unit stream size is given by this relationship S0 is the slope in meters per meter S0 is meters per meter and the second case is the case when you have well established dense sort crops so in that situation the erosiveness of the stream size would not affect you can afford to use a maximum stream size which is higher than the previous one and the relationship which is recommended is similar to the previous one so it is almost you can see here that is almost double than the previous because we had used a coefficient of 1.765 in the previous case here we are using a coefficient of 3.53 and this Q u you are getting is in meter square per second okay the order of magnitudes the maximum flow rate which we have just written the two equations for two different cases with respect to the one case we have normal cover and the other case is the dense the non sort type is the sort type let us have a look at some values maybe this is the slope 5 percent afford to use a stream size now this stream size is not in meter square per second this is in liters per second per meter width of the border because the units are different so you can use a 52.8 liters per second per meter width of the border when you have such a flat slope but if the dense cover is there you can still use a higher stream size if the slope is 0.5 percent then it reduces to 9.3 and this will be around 18.8 or so similarly let us say that if this is 4 percent you might not be able to use a very high stream size this will be as low as 1.97 so you have to have you have to look at what are the prevailing conditions and other parameters will be will have to be decided by those relations. Similarly the in general the depth of flow will be a function of how much is the ridge was the ridge size you have is when you are constructing the borders you will have to enclose it with the ridges all these these borders which you are considering so far we are not looking at the length in that manner we are assuming that we are we can use the borders in two manners one you can have open ended borders where you do not have the the ridge at the downstream end so the border is not blocked we will come to that later stage at a later stage where we can see that how we can look at those borders where we have the end blocks in place in position because in the case of borders without any end blocks you might have some surface runoff some runoff can take place so that runoff if you want to avoid you can use the borders with the end blocks. Now when you are looking at the maximum depth of flow the depth of flow let us say at the side it should not exceed and you cannot allow the to get accumulated up to the height of the ridge because once the ridge is over toppled it might get washed away so you have to have you have to keep some free board it should not exceed the height of the ridge minus some free board this free board this free board is normally around 25 percent of the ridge height that is the general criteria which is used that one fourth of the ridge height you keep it as a free board so your maximum depth should be basically around three fourth of the ridge height in terms of the actual quantities value which is normally used is around 150mm the depth does not exceed around 150mm in most of the cases but in some cases if you have a soil which does not have much erosion problems then you might use some value which is approaching around 200mm this is to be used only in those cases where you have non-erosive soils the soils are not as erosive as in the cases where you are using a smaller depth but the recommended depth is around 150mm this also these were the approximate ranges but you can also find out you have the relationships which can give you the depth of flow the maximum depth of flow at the upstream end the two cases which have been considered we have already seen that the gradient of the border will make lot of difference in terms of what is the normal depth which is getting established and we had said that if the slope is more than 0.4 percent then we will call it as the high gradient border otherwise we will call it a low gradient border. So if you have high gradient border you will achieve the upstream end you will achieve a normal depth and that normal depth can find out using this relationship and this relationship all these quantities we have already defined the units are same this is in meters kth per second and the dn which you are getting this is in millimetres the other case when you have low gradient on this case you might not be able to achieve the normal depth depth of the upstream end is given by this relationship this is the case when the slope is less than equal to 0.4 percent now you can find out the actual d and then you can see whether is it within the permissible range or not okay and you can also see whether your the edges which you have provided will they be able to take care of the depth which will get accumulated with respect to the other variables because this will be now dependent on what is the k l what is q u and the n value that was the maximum depth of flow let us look at the stream size minimum stream size you can afford to use this is the condition which is the other extreme you are using the you are trying to find out the maximum possible stream size with the condition that there should be any erosion whereas in most of the cases you might find that is not the maximum maximum is constrained by the other restrictions the availability what the what stream size is being made available to the farmer so he might not be able to achieve the maximum stream size which we are talking about but minimum is more important from his consideration because minimum stream size is achievable he might have the control to supply to apply a stream size or use a stream size which is as low as possible by the same time he must know what is the minimum stream size which is practicable which is suitable so that has to be seen from the angle of what is the what will give a sufficient spread what stream size can give a sufficient spread over the border length so from that angle the minimum stream size we must this must be sufficient to spread over the entire border strip okay minimum stream size we designate it as to your minimum this is given as so you can you check your minimum stream size whether it is below this if it is below this then you will have to revise that minimum stream size because that will give you a very low efficiency which would not be acceptable this is another check which you must apply on your design parameters on the stream size which you have computed from the previous expression let us talk in terms of the other important parameters which is the slope if you are if you want to change the slope the prevailing slope that is the parameter in your hand you might if you are forming your areas if you want to relay your areas you might like to change the existing slope to another slope so in that case you can you can even think of providing a slope now what slope should be provided what slope is reasonable slope that is what you have to you have to know the limits what is the maximum slope so if that is the situation where you are you are interested in knowing what is the maximum possible slope which can be used you can use this relationship all these terms the Tn is the net and this is the lag time which we have already seen in the previous class we had explained this is basically the application time Tn minus Tl is the time of application which will be required and yn is the depth Ed we have seen is the distribution pattern efficiency and n is the mining coefficient normally the slope any slope which is more than 4 percent should be avoided so if you get a slope which is more than this should be restricted below this but in general you can for the prevailing conditions you can find out what is the maximum possible slope which can be used and you can check your slope against that let us come to the border length maximum border length this is usually limited by the maximum unit in flow rate depends which slopes you are using if you are using steep slopes stream size has to be the tink factor and if you are using the flatter slopes in the maximum depth of flow will be the governing criteria but the maximum length I use this expression to find out the maximum length this is basically the same equation which we had used in the beginning you can find out for the maximum possible stream size what is the maximum possible length and in some situations if you are intake rates are very low you might find that you get a very very big value in general any length which is greater than 400 meters should be avoided length in general should not go beyond 400 meters it will become unmanageable and all these situations one more thing that we are using at every place we are using Ed by in case you find that the Ea is not 100 percent if you are certain that Ea is some value which is less than 100 percent then you must use along with Ed you must use Ea also okay that is very essential unless you are certain that Ea is close to 100 percent so you can improve upon all these relationship wherever you have used Ed you can substitute Ea into Ed if Ea is not if it is not known to be 100 percent if it is less than if it can be seen that yes it might be less than that so you can use that actual value. Let us consider cases where you want to use the borders that means you are using the end blocks you are trying to restrict if there is any surface runoff you are trying to restrict that surface runoff by putting a blockage at the end or by constructing another ridge at the end but then when that happens basically let us first look into that why you should think of that because any surface runoff which is taking place is going as a waste so it is reducing your overall efficiencies and you can think of using the surface runoff in some manner there are two possible options available those two possible options are the first option is bound the runoff onto this extended length so all that surface runoff which was taking place earlier if you find out how much length of the border has to be extended to accommodate that additional runoff which was available so you can afford to extend your border length and consume the surface runoff in that extended border length. That is one way of handling this the second possible manner can be to reduce the stream size so in the second case you can reduce inflow rate in this case you have not changed the length of the border is the same as the original length but in turn you had you have reduced the inflow rate to such an extent that there would not be any surface runoff. Let us look at the first case in the first case when you are extending the border you think of extending the border which the border can be extended is limited to conditions condition a is in this condition what we are saying is that the length covered by an impoundment is maximum depth infiltration infiltration depth what we are saying is that the equivalent length or the length has to be increased in that case will be y n by basically what we are saying is that if there is a the slope this is the slope of the area if we know what is the up to which length will be equivalent length after which it can be absorbed. So this is a very simple formulation and y n is the units which are used y n is in millimeters earlier is in meters and S0 is in meter per meter. Now this is one condition and the second condition is that length which can be adequately irrigated volume of runoff what we are checking is that what we are we are interested that any extended length which we are trying to make use of it should have sufficient depth and it should also be in a position to take care of this requirement which is in this extended length properly. So that from that angle from the requirement point of view this extended length is given point of view if you try to extend the length without looking at what is the requirement what is the what is the chances of getting this length taken chances of getting this length satisfy its own requirement there is no point in extending. So that is what we are trying to look at both the conditions one there should be sufficient length and second that length whether is it is it taking care of its own requirement or not. If it is not taking care of its requirement then we will reduce the length to that limit where it can take care of its requirement. So we are out of the two conditions we are choosing the minimum and only that much length is extended. This in this equation E d is same as before the efficiency but r i is the factor which is dependent on the intake family that takes care of the effect of the intake family on the roughness of the so this factor. Now these are values which are made available for different intake families, intake families give you the values 9.8, 0.01, 0.5, 2.03 these are the factors which are recommended factors for different intake families and similarly the other is between mining and these are the values for recommended for different. The impact of different roughness and the intake families have been taken care of in finding out what will be the equivalent length or what will be the length which is which can be extended to account for that surface and off which is being produced. I think we will stop here, I can take on any questions if you are there.