 highly influenced by the pressure, drilling pressures in the network of the sprinkler irrigation system and the wind conditions which are the natural conditions. So these two the factors which influence the uniformity to a large extent and we had started looking at the influences of pressure, how the pressure changes the uniformity or how it influences the uniformity and we had discussed that the pressures in the sprinkler systems, these were the distribution patterns of individual sprinkler hatch which were taken for under different pressure conditions. So we had discussed that if the pressure is too low you will get this type of distribution pattern which is similar to a doughnut, this is the pressure distribution which is having a plateau at the top and this is obtained when you have the pressures which are too high, this plateau is formed because of the fact that when the break up of the stream of the jet is too excessive then the size of the particle will be very small and they will have tendency to settle very near to the sprinkler head position which is somewhere here. So because of that you will have most of the water getting settled in the near vicinity and you will get this type of pressure distribution, the application distribution, this is the water distribution whereas under some in between pressure you will get a distribution which is more triangular type of distribution and this distribution is more suitable because of the fact that ultimately you want to overlap these individual distribution patterns and get a uniformity which is quite high. So let us have a look that if you try to overlap, let me say that this is a situation where you have one main line on that you have the laterals. So if you look at the individual distribution pattern of the individual sprinkler heads on the lateral because lateral is the one which is having the sprinkler heads. So when you talk of the spacings, the spacings are of this is the main line and the overlap will be because of the spacing, the two spacings which we have considered and these spacings are the spacing between the laterals, this we were calling the main line spacing and on the lateral you have these individual sprinkler heads installed. So the other spacing will be the spacing between the sprinkler heads on the lateral. These two spacings will decide by the combination of these two spacings. You will get the overlaps, these overlaps will be in two directions suppose the individual influence area of the sprinkler head if there is something like this then this will have its own influence area and similarly the next one. So each one is having its own influence area similarly there will be more sprinkler heads here. The influence area of these individual sprinkler heads will also be having the overlap in the other direction. So this total overlap will decide how much is the net effect of the water application at that particular level. If we draw the same thing in terms of one section let us say that f is the spacing between the laterals which is the main line spacing. So in this case the lateral here, the other lateral here and you will have some sprinkler nozzle at this level because all the sprinkler nozzles will be in the same line. So the pattern of the individual sprinkler nozzle is somewhere like this and similarly the pattern of the other sprinkler nozzle is somewhat like this then the overall application will be the combination of these two which if you combine these two you might get some total depth which is the net effect of these two individual. This is the half the portion and the other half will be on this side. Similarly this will have the other area of the plans. This total distribution pattern is for a specific individual sprinkler head. Similarly on the unilateral lines you might have these are the three sprinkler positions which means this is the zero level for these three individual sprinkler heads and each one has its own pattern. So if the pattern of this is somewhat like this, pattern of this one is the portion which is influencing up to this area similarly on this side if this is the portion which is influencing to this area. Now the end effect of this will be this this level which is from this sprinkler head plus the amount which is coming from here. This combination will give some 10 which might which might look something of this nature. So is a function totally this is your application depth. Ultimate application depth is totally dependent on how these individual sprinkler heads distribution patterns are overlapped which is in turn a function of the spacing. In this case this is the spacing between the sprinkler heads on the unilateral. So this two level of overlaps will decide what is the ultimate uniform coefficient or what is the distribution pattern, the overall distribution pattern and you will also understand at this stage that is very difficult to get a distribution pattern which is very uniform which is almost a straight line. This is very difficult to achieve because of the fact that the individual distribution patterns would not be of such a shape that if you combine the two you will get a exact straight line. But still in comparison to the other irrigation system which we have seen so far the surface irrigation systems where you are using the gravity flow you will be able to achieve much better distribution because of the this particular situation that you are providing the water from each individual sprinkler head which has its own area of influence. But there will be some level of percolation, there will be some level of losses mainly in this case the population losses and that will discuss and the design aspects in this system they pertain to having a combination of these parameters the two parameters we have just now discussed the spacing between the laterals and the spacing between the sprinklers on a lateral. This these two parameters are very important because they are the ones which will decide what will be the distribution pattern overall distribution pattern and that in turn will decide how much will be the extent of losses. So having discussed the influence of pressures on the uniformity of application let us look at the wind effects, how the wind effects uniformity of application. Now the main effect of the wind will be to distort the distribution pattern. So the major effect of or the only effect of the wind is to distort the distribution, means the distribution pattern gets distorted then the overlap to get the overlap become more difficult and that is the situation where you will find that you will be able to you will not be able to get a depth which is uniform will be more and more difficult to get a uniformity of the application depth. Let us have a look at a pattern and suppose let us take one individual the plan in plan let us take the distribution pattern of a individual sprinkler, how the if this is the if this is the location where the sprinkler nozzle is, the sprinkler head is you will find that if you try to join the points of equal depth you will get a pattern which is quite well distributed around the might be some influence if the level of wind is not very high this is a pattern which might be because of a wind of very low intensity let us say 3.3 kilometers per hour. In this case if you take the distribution pattern around the 2 cross sections, one cross section is in this direction you will find that the distribution pattern will be quite quite uniform. Similarly on this side also if you take the cross section in the other direction again the distribution pattern is not very much different than the pattern which you have obtained in the other direction whereas the situation will be very different if you have wind conditions which are very excessive wind conditions let us assume that for a similar situation where you had a single sprinkler head in velocity is now quite excessive 17.4 kilometers per hour and these are pattern which I am showing you they are the actually absorbed patterns for these 2 different wind conditions. So in this case because of this wind which is prevailing at that particular site during the period when the sprinkler was on you will find that now the if this is 0 level or 0 other patterns there might not be much difference in the pattern when where the depths are low which are the side segments but the difference will be quite excessive when you come to the central portion you will find that this is a type of pattern which gets developed where you have the maximum depth here 0.2, 0.1 somewhere in between and 0. So if we take the the section now when I take a section in this direction you will find that the distribution pattern will be somewhat of this nature which will have this and then similarly on this side if I take this section here the distribution pattern will be somewhat of this nature. So you will find that most of the water has deposited in this area because of the fact that the wind was blowing in this direction and this distortion in the the distribution pattern will create lot of undulations in the application depth which you intend to apply. Because of this reason in most of the systems sprinkler irrigation systems people shift their time of timings of application because in general most of the areas it has been found that the wind velocities during the night time they are much lower in comparison to the wind velocities in the during the daytime. So they intend to run these systems during the night time just to avoid the the wind effects. The other way of taking into consideration the wind effect is by changing the spacings. So that is another way but by doing so you might still incur some losses you might be able to take care of the requirements of the irrigation the net irrigation requirements but in doing so you might indulge in more losses which is which is again something which you want to avoid. Now with this initial background let us discuss another aspect which is very important which we have been referring to very often during our talk which is that how we how we account for the uniformity of the depth or the uniformity of the application. What is the way by which we can we can measure how much is the uniformity of application that is where we use the uniform to coefficient we had discussed that at the time when we were discussing the efficiencies that how we what is uniform to coefficient but that is more relevant to the system than anywhere else because this is very very sensitive to the uniform to coefficient. The different expressions which have been used to express the uniform to coefficient would not indulge in that we will just pick up one which is most commonly used and which is given by Pristin's and this uniform to coefficient is expressed let me say UCC which or more often we will use UC only this is to designate that is the one given by Pristin's and 1 minus summation of divided by where xi is the depth what is the depth received at a point in millimetres x bar is the depth of application and is the number of points considered. Now these uniform to coefficients are absorbed in and field through experimentation and the is a very simple experiment where you create a grid and in that grid you install this grid has to be after creating this grid you install the ring devices which are nothing but you use the small cans which are known as catch cans and these catch cans are nothing but they are small vessels which are installed at the known points and then you run the sprinkler for a specific duration and then actually measure how much depth has been received or it has been collected in those cans so that is a simple way of finding out how much is the what is the distribution pattern and that distribution pattern can be observed under different conditions but the procedure remains same and you install the grid and the spacing of the grid is again there are some guidelines what should be the spacing so as to avoid the inaccuracies and those things we will see but the way you install your grid is also dependent on what type of system you are using what is the operation and methodology or the procedure of operation are you using more than 2 liter at a time or you are using a single liter accordingly that methodology will vary but in general this particular relationship where you are what you are doing is that you are finding out what is the difference what is the deviation of each individual observation of depth from the mean and then you are trying to find out the uniformity on the basis of that deviation the more that the higher the deviation the lower will be the uniformity which is quite understandable that the if you are if all the values are all the cans they catch the same amount that means each individual observation will be equal to the mean value so in that situation your uniformity will be 100 percent. Other side if your deviations are very high they are much different than what is the mean value in that case you will find that the uniformity coefficient will decrease. So in a case if you have a situation where you have many sprinklers which might be operating at a particular time as you want to look at the uniformity with respect to the operation of the system. So if you have if you have a case where you have these sprinklers let us assume that the catch cans are provided these locations you have another you have another later these are the laterals you have another sprinkler system here another sprinkler and it is here. So all this area you will have the catch cans all these are the catch cans now when you will operate these four sprinklers simultaneously the catch in these these cans will give you the uniformity coefficient because now this area is the one which is getting water from all these four individual sprinkler heads. So the overlap is taken care of whereas it depends on the situation if your spacing is such that the overlap is uhh is such that even a sprinkler head which is somewhere here the maximum location there is also influence in this area then you will have to take that also into account. So it is entirely dependent on how your system is designed and uhh and the uniformity coefficient has to be obtained accordingly so in such cases where uhh you have a single let us discuss another situation where you have a working area time you want to know that what will be the uniformity coefficient due to that if you have different sprinkler nozzles attached on the same one now your catch can should be installed in such a way that each of this is coming somewhere in the middle of these catch cans the location of each sprinkler nozzle so now you can have the catch cans spread like this these are the individual catch cans similarly on this side once you have these installed and when you run the system in this particular case now the overlap has to be in general the overlap on the same lateral is higher than the overlap between the laterals so in this the area of influence depending on what is the uhh how much is the extent of the area of influence you might find that if you operate around 3 of the if you operate these 3 simultaneously they will give you quite a sufficient uhh uhh coverage and then picking up a one representative area you can find out how much is the uniformity coefficient so the procedure can vary that is what we are trying to emphasize here there are some recommended conditions which have to be observed for example the minimum vectors the catch can diameter should be at least 8 centimetres similarly the maximum spacing should be of the order of 3 metres you should not try to have spacing between the cans more than 3 metres and the condition which is recommended is that the sprinkler height of 0.6 metres above the average elevation of the 4 nearest collectors so the level of the sprinkler height should be at least 0.6 metres above the 4 nearest collectors then you can also absorb the other data the related data which can be important when you are performing this there is a test for the uniformity coefficient evaluation you can also absorb the data which can give you how much is the loss from the evaporation and that can vary drastically with respect to the the climatic conditions so you you should absorb the data along with the supplementation the data on the temperature the relative humidity and the related parameters which can give you the indication about the evaporation activity and those losses can also be incorporated okay because if you are if you are using the same method for different climatic conditions you might find that in one case the loss whether the conditions are very severe and they are very dry and hot the level of evaporation can be very high and you might get results if you want to generalize those results you might find that they can be problems later on so for those purposes you will like to have the data on wind conditions, the data on temperatures. Let us now discuss the aspect of adequacy of application so far we have looked at what is the behaviour of the sprinkler irrigation system but why we are using the sprinkler irrigation system is to use this system for application of water which is basically meant for taking care of the crop water requirements so unless we look into the question of adequacy whether that amount of water which we are going to make available how adequate that water is that is why this this term of adequacy of application has been introduced which is very useful in designing the system because you have to evaluate your system with respect to some parameters some quantities and adequacy of application is one term which has been introduced. So if we look at the final requirement which we want to take care of which is the net irrigation requirement, this net irrigation requirement how much this net irrigation requirement is there, net irrigation requirement is basically the difference between crop water requirement, we have seen this in detail that why we are irrigating to take care of the crop water requirement, the crop water requirement is a function of the climate and the crop water requirement is put together and that crop water requirement is also to be associated with respect to when we have done the last irrigation. So the crop water requirement and there can be another quantity which can be adjusted in the crop water requirement which is the effective rainfall. So if you want to take care of take account of the effective rainfall, effective precipitation you can say this over a period what is this period since last irrigation this much difference how much is the crop crop water requirement during the period since we have given the application the last irrigation application and after taking into account the effective rainfall during this period, the period in question that is our net irrigation requirement and we have also seen just now that this net irrigation requirement we achieve through the superposition of those individual distribution patterns. So what happens you might find that looking at those patterns the way we have seen them there are some places where you are having more water, there are some places where you are having less water, there is some undulated application you might find that it can be something of this nature. So if we want to look at the overall field you have to see in terms of the total area or the total field how much area you have been able to achieve at least the net irrigation depth which is the required depth and those areas where you have not been able to achieve this net irrigation depth those are the areas where you are having deficit conditions. So the adequacy has been defined the term adequacy when defined to address the various concerned items the first one is that what is what portion of the field you received at least the net irrigation requirement just call it. All those areas which are at least receiving the net irrigation requirement they are adequately irrigated all the remaining areas are under irrigated areas. At this adequacy level we normally express in percentage if we say the adequacy level is 25 percent that means only 25 percent of the area received the irrigation equal to or greater than the net irrigation all the remaining area received water which is less than that level the level of net irrigation. The two things which we have introduced the uniformity and adequacy these two things put in conjunction these two things when you look at the two items together you will get the field how well you have been able to irrigate the area the uniformity as well as the adequacy. So if you try to establish a relationship between adequacy and uniformity we will explain this through another graphical presentation let us assume that this is your this is a field where I am expressing this as percent of area 0 percent we say this is 100 percent and the applied water depth is different. So if we take for every 10 percent interval the increment how much is the average depth we can normally you can show it as a continuous line but you can you can show it as a bar if you take only 10 percent of the area in one interval. So if this is the actual applied water depth which I have either obtained from the by using the catch cans or by using some other way you might find that if this is the way it changes so this is a total variation and if this was the irrigation requirement if this is the level which shows the irrigation requirement and this particular case this was the irrigation requirement and this is the actual application which we have made at this level if this is 50 percent level what is the adequacy of irrigation is only 50 percent because only 50 percent of the area is receiving equal to or more than the net irrigation requirement because your requirement was this is the level of requirement and this is the area this area if I shade this area this is the area which is the deep percolation we did want this water this water is not being used for the crop production this is the excess water which has been dumped because only this much portion of the water was required as this is the net irrigation requirement whereas on this side this portion in this area on this side means for the remaining 50 percent of the area the irrigation is not adequate it is under irrigated this area is under irrigated if you wanted to have a higher uniformity coefficient then for the uniformity coefficient to be higher this disparity this deep percolation extent of the area should have been minimal so you should have got a distribution pattern which is giving you depth the actual depth which is quite closer to the required depth that is what you have to achieve for a specific level of adequate irrigation or the adequacy of irrigation. These two factors put together they will be the one which will be very useful because although the fact that these two things are not independent they are interdependent and they are also associated with the other indirect forces for example the economy of the system. I can get a much better uniformity coefficient if I am willing to have a very closer spacings between by adjusting the spacing between the sprinklers and the spacing between the laters I can achieve much higher level of uniformity coefficient thereby reducing the deep percolation but at the same time my expenses go up. So it depends what type of crop you are having what type of condition you are having and thereby you can decide what type of system is adequate for your conditions. Therefore it is very important to understand at this juncture it is not just merely a function of how these things vary there is lot of subjectivity and that subjectivity has to be resolved by many different parameters some of the parameters are economic parameters the other parameters are also dependent on the crop which is an in question the requirements of the crop are how sensitive the crops are what is the value of the crop how much you will lose in terms of the yield whether that is justifiable or not so there has to be a trade off that is why these designs they become subjective you have to you have to put in lot of effort in arriving at those final parameters and those parameters might not be generic parameters they cannot be you cannot say that yes these parameters for these set of conditions if you have applied in one area they will be true for the other area also it is not true they are highly subjective because of these different conditions. So we will try to learn more about these items in the next class we will stop here today if you have any questions I can answer your question thank you.