 Hello everyone. Welcome to NPTEL course on groundwater hydrology and management. This week nine lecture, we have been looking at the application of the aquifer. How to layer aquifer based on data? What is the bore log or litho log? We have seen how single column sample has been taken and different layers have been identified and we also saw how to take multiple cores or lithologs and then connect them between them, what to connect the understanding and information between them. This is very important for understanding the layering, the dominant layer typologies and to estimate where the water is coming or where the water is going to be stored. This we are going to move on creating more understanding using fence diagrams. These fence diagrams are driven by bore logs data. You can see each bore log data is given on this each line. Then each line is connected based on the layers. Let's take a boundary for example. This is your watershed boundary where you had all these wells or your bore logs. You have all these bore logs in your watershed boundary and you try to see how the layers are matching between each other. Now you see that the top sorry which is given in brown is very thin. If you see from the top of the fence it looks like all are same elevations however it is not. The elevation difference is available in these regions. So every log has its own number and name and there is an elevation until which it has been done. So you would see a thinning or thickening of the layers depending on the how the layer has been formed. So if you look at here, look at this layers and all, you would see that it is all parallel. So all these three wells well 1, well 2, well 3 for example, have had the same thickness at the same height. So you can easily make a parallel and that is how the layering happens. But after some time it stops. It stops abruptly. You can see here the layer just stops. So you should also stop on the diagram. So for example from this data point to the other data point it is there however in this lithologue there is no yellow color aquifer or layer. So it has to be stopped the same here also. And then if you have an angle for example the orange you can see an angle coming in zoning in. If you have an angle then that angle can be used to understand that it is going to small thin thin and then pinch out which means it just goes as negligent. For example I'll just draw it here. So the layer will go like this. The thickness will be big and then slowly small small small and then nothing. So that's where it ends. Okay so this would be a different material. This would be a different material. But this layer which is in between the layer sandwich is going to be thin and stop. Because it's not always parallel. You cannot expect the position or the layer forming to be a parallel phenomenon. So what we see in the fence diagram is since it looks like a fence they create these diagrams to understand where the lithology is different, where it is same and how it quantifies the thickness of the aquifer and or the water bearing regions. So the connecting layers are found in the multiple lithologs and then the aquifer deposition stratification is understood. Both are all same meanings. Okay then as I said Bohr log is same as Bohr whole core sample or lithologs and just the name differ between the region but the understanding is the same. Same way aquifer disposition which means how is the aquifer layer or stratification can be understood by this data and fence diagram. Also you'll be able to look at the aquifer pinching and the aquifer coming out called outcrop. So what is an outcrop? For example if an aquifer just a thick rock permeable impervious rock just comes out of the aquifer and then cuts through an aquifer it is called outcrop. Why is this important? It is important to know how the water would flow and why suddenly there's no water on one side of the outcrop. For example you have a layer that's the ground surface and you have a thick layer which goes like this okay and this is cutting your other other aquifer types. Because it is cutting and it comes out a little bit it will you call it an outcrop. An outcrop would actually kind of divide the land underground into couple of layers or stop a particular layer for example this layer stops and then another layer is here the dominant layer is here. It's kind of a division and that actually gives you an idea of what kind of water is present why the water is different on one side of the outcrop. Moving on let's take another aquifer stratification example again I'm using it very cautiously that the word is different stratification fencing disposition all are about layering of aquifers okay so don't get confused when you read books or papers I'm that's why I'm using it thoroughly intermittently and you know changing the terminologies because it's all the same. So you have a watershed area done by Kumar et al you could see that they've taken the lithologs or the boreholes or the bore log in these locations you could see it is not equally spaced nor it is you know gridded which means it is like fully represented for example here there's no data so they will take where it is feasible and where they want to do some interventions. So if you look at it then they would connect these logs together to create an understanding and since it is a 3d right you have a 1d is a depth and x y is your 2d so the z which is the depth so this is a land and this is x y plane we call x and y okay so it is spread an x y plane and then you have the depth as y i'm sorry z the depth is z so you have different depths which can be converted to a 3d model see a paper is just a paper right so this is just one sheet is an x y plane okay but if you add a thickness to it then it becomes a 3d plane because this thickness where do you see or a thick layer like this becomes your 3d damage now i could do like this and this to see that oh i'm not only having a 2d plane but also the thickness also i could see like for example like this right so you can see the x y plane and also the thickness in this fashion you can only see the x y plane in this fashion you can only see the z plane only the thickness but then when i tilt it a little bit you could see that the x y can be visible and v y z thickness can also be visible that is why you can see this tilted land it's not that the land is tilted because look at here v1 is here okay and then v2 is here so it's not like v2 is almost on the same line so they will tilt it in the model when you put these data and then supply these data points then you can tilt when you tilt it then you could see clearly how this aquifer is present so it's just like a small toy where you could tilt and see up down like you see interior of a car nowadays online right you can just click and turn the car same thing like this so what you see here is in b1 you can see b1 you have the predominant layers of clay and then i see fine to medium sand and then i see coarse sand and then medium to coarse sand etc so it is not the same this coloring is not the same as here but as here you get more fine sand v8 and v9 so v8 v9 okay so the process of which the materials have been formed is different and that is evident in the different colorings of the layers it's good to have these colorings and as many layers as possible when you do a model there is no point having this many layers because of the computing power which is needed and also most of these properties if you remember in the porosity hydraulic conductivity lectures the properties are also in the same range so they'll just club everything and then make it one or two three dependent dominant layers and you see also the position of the layers is different you can see here violet on the top which is sandy clay here it is on the bottom why that would be or fine to medium sand is at the bottom it is on the top here why that would be the case is because this blue color which is your sand which is being deposited on top of each other can push down the other layers okay so let's look quickly between v3 and v4 okay zero is the top of the ground and then you go down to the depth so it is all 100 meters deep core sample has been taking 100 meters and then you could see that in some places the thickness is small some places is big it's because they didn't dig deep enough but clearly visible this one side which is the b9d8 this side has more fine sand so if you have fine sand if you pour water on it it will just drain no point of having aquifer recharge activities whereas here it is clay with coarse sand and coarse sand with gravel which will have more water holding capacity specific retention aside right so you could see how these are placed and how they talk to each other in terms of understanding the layering of the aquifer let's move on now if you do this for the entire India okay so just going back you could say that I could color this area before we talk about the India scale what can happen is for example this is all pink so I can color this when I have much colors online let me try okay so I can color all this aquifer pink okay so because on the top it is pink and then this blue or violet let's take a mixture of those colors okay so this is a blue violet I think I can extend that to here also okay and then this part is kind of yellowish orange okay yeah so now you see three different aquifers let me draw the line so that you could actually understand how this is done so this is all orange and then you have your pink which runs like this and then you have your violet which runs like this yeah so now if you if I change the image okay if I'm going back now you could see that it is three distinct layers which is or aquifer on the top it is being demarcated from the top plane because that is a dominant on the top that is the same way this India map has been created wherein they would look at the core samples the bore log data and the little log data taken at multiple points okay they take it at multiple points and they would for example like this and they would just sorry not to know like this and then they take the top of the bore logs and then they match it together if the matching is done all the aquifer is mapped okay so this is how the aquifer mapping is done at an India scale they don't want to keep it you know like in one aquifer for the entire country it is not possible and it is not correct so it's good that the samples have been taken and at least the top the top layer or the dominant layer throughout the medium has been identified what you see here is of the vertical column of the vertical column they would take the dominant one type of the aquifer and here you can see unconsolidated sand silt is in the blue that's why you see in the previous one also there is a blue color correct which is saying it is sand and it is along the riverbed so that is where a lot of these deposition happens and then you have a Reckon basalt equivalence which is the hard rock region and then you have your semi-consolidated corduona sandstone shale and the equivalence around here mostly the hilly regions igneous intrusives also the hilly regions consolidated precambian pink in central India and then metamorphosis metasadiments etc okay so the idea is each core is now taken and when it drastically changes from the different core they would change the dominant material okay so please understand that the dominant material has been changed throughout depending on the bore log data and the whole India map can be made for sure they would have taken the data and used in understanding these maps or making these very very important maps now let's look at how it's done I showed you how the data is available right so the data you would date and then take and put it across as cores and in a graphical sheet like this and then you would make the layerings or understand how many layers are dominant for example this data would be the same as this one which means with seven five layers but then they would club everything into a dominant layer which is what you have three layers here three maximum four layers one two three four okay so let's see how manually you do the joining of these layers so how is it done manually assess the number of layers per core so each core you take or a little log or bore log and then you take the dominant layers you understand how many dominant layers by the sample and other things you then estimate the thickness of each layer okay so each layer thickness is estimated merging some layers into one here's what I said some layers have to be merged to one otherwise you'll have these many multiple thin thin layers without making sense because you you want to store water and you want to use it later for agriculture there is no point having multiple layers which don't give add more value to the system okay so how else would you do with the mapping you would have to align it with your objectives my objective is to understand the deep aquifer recharge I will go as long as deep and then ignore the top much because I will be focused on how is the water coming down and how is it being clubbed together into an aquifer down deep aquifers you won't see much bifurcations only the up regions you'll see more bifurcations and different types of layers because of active things which happen on the top like erosion you have deposition, alluvial, colluvium where rocks move all those stuff then you draw the study graphic lines okay manually this is just a manual methods I'm talking about you understand where the top is top of the layers to the top so top to top you connect one line same here let's do it quickly for you again so this layer black layer this is the top to top is connected in the grayish layer the top to top is connected but then this layer is given off because ignore logs without that depth you don't have that depth or you don't have that sample if you don't have that sample you can run through with the interpolation so what you are doing here is just basically interpolating the type of rock from one point to the next point because there's no data for example if I have a data well okay if I have a well here which has different different materials around this area so then what would happen is you would draw from here this level and then come back okay same thing from here it will go on to Canada and it will not come back so the layer won't come back because we are looking at one direction and more importantly the layer has to capture the dominant layer not all layers together okay so think about it from the top you connect the top to top okay if you have one layer and there's not the same type of layer you just interpolate it throughout interpolation is how you fill a gap which is in between two non-values right so you interpolate it the surface is a continuous data every inch you have surface but your observation is a point data only at some locations you have points so it is up to you to make sure you arrange them in a particular fashion so that you have the layers I'm saying the layers are engine so that you have a dominant layers and you connect the layers if you don't have a layer it's better to know that well because it might be like just in that well you didn't have that data if you have it another data it could have mixed it could have been a sampling error in no laws without depth which is here this law there's only suitable for the top most layers not the bottom layers here the bottom layer is the third layer if not interested in that then truncate a layer if not extending okay if you're not seeing the layer extending it's better to truncate okay so that is the manual method now let's look at the software methods there are multiple multiple software available in the market okay and the softwares can be open source which is free or it can be proprietary software which is you have to pay so the software is like a computer simulation model it simulates the aquifer layers based on your data what does it do let's look at the core function so it is a computer simulation based algorithm there's a lot of mathematical statistical models where it interpolates one point to another to make a surface so like this surface again you should understand that all the surface was made by just points and interpolation okay we had a point a data like for example it was data here there was data here there was data here you just interpolated it between them based on a method and then you got a surface it identifies all layers all important layers or non-important layers are identified because it is a model it can do all the connections okay it can actually look at if it is different different connections different different layers thicknesses it can capture this continuities can be easily monitored through your interpolation techniques because you don't know how do you see if it's only two points and you're making a surface it's okay I can interpolate whether there's a well here there's a well here there's a data point here then all these data points have to be influencing this interpolation that is difficult to do by hand okay and that is where a simplified model is okay to do by hand otherwise it's better to use a software like this where it will tell you if the discontinuity is happening or which means a layer is going and then it stops it's a discontinuity okay or the layer is cutting through other layers which is an outcrops all these can be perfectly modeled using the interpolation between the wells and then it picks up the net type of your layer please understand that there is multiple models as I said and all of them are based on the interpolation statistical methods it is better to choose from literature some model that has already worked for your area let's take another look if you have multiple wells or multiple data points for lithologs okay how do you know which one has more weightage to influence your output that is also taken by your software so for example I have four five okay let's have one more six so this is equally distant from this slide this slide this slide and this slide so which one should you choose to make the boundary of an aquifer in a software it will choose everything and then finalize one or finalize one team however in manual you have to do one pairing at a time okay so it is very difficult it's better to do it using computers and especially the well trained models such as modflow r r is an open source statistical model and a mapping model or graphing model so using ggplot2 and grid you can do that gms modflow is a proprietary version whereas just modflow from the usgs is a free version you can use either of them surfer 2d 3d has been widely used across the world it is expensive but it has been tested by a lot of people so a lot of scientists and researchers so it is better to use your surfer if you have the budget because it has been widely used and core and rock is also new and it has been widely used so this is a surfer package where it has a 3d version and as I said you can pull turn it around upside down and then look at it whereas here which is your r-based model it is not as robust with many buttons and graphics but it gets a job done basically it gives you from 0 to 40 centimeters in each slot in each experimental setup okay it can take and look at what is the dominant layer and also the nutrient properties based on the samples that is taken from the ground so we have now seen that it is very important to have these layerings done so that we understand that the layer has to have only dominant identification points if it is very small the layer should not be called for example it is a clay layer it was only 10% clay or it's the first clay that you see no so all have to be weighted in and then you give it to the model the model will tell you how many layers is possible and how many layers is not recognizable or not recommendable recommendable if you go to the deep aquifers you'll always see one or two dominant aquifers so please think about it and then we will see you in the next class with more examples on these methods and technologies before we finish I'm going to show you the introduction to the data for this which can be bought from the WRIS website the website link is given on the top slash litho log okay so litho log is same as Bohr log and Bohr poll sample what you could see is you could go and zoom into this website each and every location which has the data would be highlighted it will tell you the year of the data which is 2001 and other aspects most importantly the data pulls out like this where you have a litho log and a layering already done so everything is done you don't have to worry about which layers to choose how many layers are there etc it's all done for your benefit and then you would just use it and cite these people especially Zach who has worked a lot on these systems to improve the groundwater hydrology in India okay so this COVID did not have much engineers working on field projects right so it is important to take data from these websites which already have the data and it has given you the water level static water level data what is static it is not a pumping well if it is pumping then it moves up and down as a dynamic well this is a static well taken by the state board which I'll be checking with you guys in the next lecture on important data for groundwater management with this I've conclude and then talk more about these lines and other things in the next class thank you