Mapping vulnerability of groundwater to contamination using DRASTIC method

in this video we will make vulnerability of groundwater to contamination using plastic method drastic method is an overlay analysis technique for determining the aquifer corner ability it uses seven hydrogeological parameters to calculate drastic index these parameter includes depth to water net recharge thank you for media soil media topography the impact of bed ozone and hydraulic conductivity so let's see how it's calculated first we will get all the raw data then converted to drastic parameters so I have already done it so you will find in this exercise these data set already prepared we just have to process this where are meters which are depth to water which is d net recharge which is our aquifer medium which is a soil media which is s slope which is T or topography and impact of pitocin which is I and ironic conductivity C which makes up a drastic so you will process it all then energy I use then make drastic vulnerability where of groundwater contamination so this is the equation to calculate drastic index so here you have rating of your first parameter depth of water and then there is a weight assigned to it so it is a weighted related method method which is basically and weighted overlay method to calculate the vulnerability using these 700 logical parameters so how to assign this rate and how to assign this weight we have to see the literature so this is the table which we will use in this exercise to calculate the weights and rates for each parameter so for depth water we first we have to classify our image into these glasses so then according to each class we will assign the rate and each parameter will have a weight so suppose if our depth water ranges from zero to one point five meter then we will rate it as 10 and if it is 1 point 5 to 4 meter hooray trees is nine and one point four point five to nine meter it is seven so shallow water tables high ratings and deep water tables no ratings and then once we have rated our depth water special into the area then we will assign weight five so you will see it it also will do similarly for each parameter we will have rating according to its classes then made according to its influence on the contamination stone contamination so what is the procedure for doing it first step is you open arcmap then add your data of all the parameters which is already prepared then we have to classify our layer according to Table one which is this classification so we have to classify according to these ranges once we have classified these lengths will see these changes according to the table here then you can assign these rates using raster calculator once you have assigned this day it's using raster calculator then you can again use raster calculator for using this equation so here this is the rating master and after rating master you will have these weights so you can see that two water table is gained five eight that we charge for a key for three turn media to top topographic one but also five n atomic color to d3 so you can see there five four three two one five three so these are the weight related equation so this B R we will prepare based on the classes and then once you have calculated the drastic units then you can easily can fire it to low vulnerability or terrible I will too and very - Lorenzo so we will first open our trap and have the data so what it is drastic D or a yes deal I see so this is your drastic parameters now first step is to classify according to its ranges has given in this table which is Table one so first we will take parameter depth of water and classify it so either do it here you can see I will just close all other parameters our depth to water table ranges from 0.7 a 20 to 7.5 inches so it is from the top of the surface to the water table so now let's classify it so we will use classify we will classify three now given assignment threshold so you can go classifying can put it here manual and put the ranges like our upper ranges are one point five four point five then greater than four point five so in our case it goes to zero point five so up for them so here in the labeling because I know how the ranges are so I will type in it according to the tables of zero to one point five and then one point five to four point five so it's just labeling you actually ties yeah so you can color it if you want light color it into shallow do be for the villains that's okay so you can see it here you have one zone where you have deep water tables there is another one what is shallow water tables and from moderate water levels then you have a shallow water levels so it is basically assumption of this method is when it's shallow here from the more contamination when it's deep you've got less prone to contamination so that's why you will see invades shallow will be assigned the maximum with great people be assigned less rate so it's ten mindset so now what you have to do is basically convert this yep water classes into rating which is basically dr so you have to rate it so you all this area which is greater than 4.5 will become 7 this mortared area will become nine and this shallow area with the content and plastic so let's let's first do for all the parameters and then we can be like indicating once so what depth D is done so we can minimize it now our recharge ready for recharge for recharged we have this range 0 to 175 175 foot 250 then greater than to recharge is given a limit of various n will be charged so let's see classified we'll go to property symbol classified we'll give it a three classes and we know now the Rangers will put a ban on it when you ranges will be 175 250 M get another 250 C so 175 150 and then greater than 250 whichever it is so I will again enable it here don't just sign it fella they fill it here like as the table hundred to 175 so all minimum value is about 36 then 250 and then greater than 250 press ok so most of the behalf because it's an irrigated area surface education that here we have less because of only being follows acting so now let's come to like if a media so we have consider like it's a highly transpose of sandy aquifer there are almost the same X where it is aligned with so it's only one bed here so we can assign directly we can assign directly the weights so there is no other classes so we have only one time which is sand and gravel so clear it's already one value in an aquifer so as you can see only one value now let's come to swine media so we have three type of soil media so we have to assign send room and play so we have a three types of soil maybe I am and we have to assign each value a number later on so I I know that in my case see my rotation so I can see which type of soil it is yes my phone is sandy soil - is blue me and threes clay so I can just label it so I can identify later on this is sand this is rule this is great this is a poor soil usually luma clay because of the agriculture area or poor soil like it give it a color speak a little I see later on so it's clear that color which is suitable description go see the area immediately there is sending at the desert side in some sand and there are some patches of you said recently because of the river migration may be so this area is desert so sandy stuff so now let's come to the topography or slope so it's really a flat terrain this is some high values I think this is error but this line is really out of the range because mostly I know what this is reflected in some sand dunes maybe si so that's classified how we have to classify we have to see here so as I know it's very fair shows you know to group or so slow it's only one anything so you can just see in clock make it to process yes this is some outlier see some out by which this this values this will electoral will assign it a zero ready little the in theory classes ask you - I'm here is I'm waiting on you so let's go forward for so when this impact of my doors on is also like mostly there with Rajee of upper soil is like said since the battlezone is also - and you is a continuous aquifer there is no thinking here as much same place and clearly a 0.6 and less clay clay layers so we'll assign one value sets already one system so when we will define the rating we can use it so that's okay now the conductivity ranges so for the variable conductivity we have to give ranges conductivity which is less than four who interpret a make a bottle for two first to hold it on so we have to divide it into these three classes given up on bow the values for twelve and a to the 12 so before so there you can see it the ranges between minimum is your 24 and maximum is 34 to 37 see so it's it will be then we can take this one class just take one class here because most of the values are painting in 12 to 30 minutes that's okay so now we have we classified all our images according to the table and now we can rate it a call you to the table which we have using this is basically taken from the error at all 1987 the approach which was given first for this drastic calculation now what we will do is assign rating to each parameter so we have classified according to the table and now a reading so for doing that we have will use declassify too you can press ctrl F to find them to be classified so you can select this reclassify anticipation analyst now select D your first parameter you need to reclassify just make sure that you put some u values like 0 to 1 point 5 5 is equal to 10 and one point five to four point five is nine and four point five and greater than four point five is seven so I will name it as VR rating not if save it press ok so there is some value sweeter which are out of range so let's see but it has classified correctly and we have given a routing number so what seven is deep water tables nine is moderate and ten is a one channel now let's do same for our recharge we will do same for every charge values and use the same tool which is a classifier selector be charged so am i there for ranges thing you can correct it here so let's does reclassify our way I will make it three so just make it a little bit higher so you can capture your so make it a little bit higher so that I can capture the values so I have to capture all the values so 100 to 170 5 is 6 so you get 6 and then 175 to 250 it's 8 so here is a little bit change 175 just make sure that whether you need classified correctly before so we did some mistake or this connectivity then there is a value which is greater than 250 to 750 we'll give it in like six eight or nine so same rating is over so we will put it as our our octave just to check once again that our values are correct hundred to one seventy five to six one seven to my approval please 800 I it's safe so for the safe side I am just putting 100 Arizona although there is no zero each I've seen this the safe side it's completed let's see it again you can see it it has given six value 82 anodyne value as per the classification now we will come to another parameter which is kiefer and in our aquifer media we have only one media so we just have to put them just assignment the stuff so you can do it here in which classify too low you can simply do it later on so you can use Gnostic calculated over this so for the sake of consistency I am using three classify to use my old value is 1 so if I was eight I will give it a name we are top if that's safe press ok you will see we will get the value that's good now coming to S which is SOI SOI media so our one is send to is low and three is clay soil these are coming to it so let's do it with a little glass if I duel again you spoiling my dear so nine five and three five you fifty three so check it once again save it as as not if they're safe that's okay we will get these medals three is your place stuff my name is Cindy stuff five is Lulu sorry so nine is given to 70 soil because there is high infiltration rates and developing fastly water do me as less so is five or three minutes so now coming to our topographic slope so it will look like it's not correctly classified so there are some values which are out of the range so I will give it zero and for 0 to 2 I will give so I just have to reclassify it once again so that so I pick my because 0 D 2 and K 2 then we have these two numbers so we will assign Z greater than 0 and that's for the table so let's use again the reclassify tool select topography 80 and from 0 to 2 we have to give 10 value another we can use 0 so because these are outliers we don't get not interested let's see if that's okay now here so there are some values this is somewhere else which there is some value which are really high 80 values some may be more apply us all to the system we can handle it or leave it here or we can just remove these values which are 80 another way is to give it high range as we didn't judge SAT multiple ways to do it so I will do it again and just give all all the number of ten values so what I will do is specifically this we classified everyone class just so it depends but because it's all that zone is high risk of contamination and all the zones so I am giving it high risk so it depends on you will study so I am taking it in the high risk instead you just have it little bit more so capture all of the values so we'll assign it as what was that TR so TR already existed so I will give a TR to save it that's okay so now you can see we have one value which is having high risk rating then we have better zone so for send clear we can assign one once and we can assign it so we have considered like one high resume this one Barry Williams again to classify doing impact on Bishop widows own n we are keeping it in to the highest offices eight million high racism and we will give it as ir value press press C messenger so you can see the whole value will be hit that's good and now the conductivity range again in this we have one one conductivity range so if we are doing like big regional so we are in like 12 to 30 range so therefore let's save press ok so now you have created all the rating masters now you simply have to put the di equation formula so there is someone out here also so this data Corrections you have to do this so and so forth so look this 24 is our client so as this is the one value so I will just make it sure that I capture this I will do it again so just to capture it a sign like give it some no value whatsoever 23 3 because it's coming in here a sign it is for when you make it CRT because CR already exists make it see how to save it press ok we will see this outline with an hour ago now we have created all the rating masters now we simply have to use raster calculator to can put this formula where we have already put in will do one by one and you will see it how calculator open your roster calculator you can search it in control f8 press Enter nice to meet you master calculator so just see from here so our first weight is 5 5 x ur about depth to water table which is d we are reading master put over the brackets save then press + then again the waiting just for problem is the syntax error there I don't know what specific say let's see some type of syntax and no more it is good again DF x 1 Plus that's something I don't know why it was giving me so excited before so now we will use a live person should not come here but let's see we'll put on the formula and see demon now we charge and for mating also everything is phone then we will after we charge is capable they are getting far then we have to multiply it with the waves three then again we have to multiply s which is our soil and s are into to us are multiple is the mating officer then plus TR into one so simply T are only we have IR into five oh what a clever fight then we have see you just put the brackets x 3 so now this is our drastic index equation we are using rating rosters x the gates ending of the parameters index that's okay so it has calculated your vulnerability index whatever that ability index now you can easily classify it to classify into the range of this so you know which is no wonder will moderate I am very high so hundred when 100 upper than 140 200 and 200 so let's see it's hundred so one lowest is 150 one so we are already in high Wonder Invincibles you can simply classify it this way to values so because we know that now in our zone we have basically just looking at the numbers you can see our whole data set line hyeondo so it's only one zone 141 to 200 these numbers also depend on the area which you're working according to my experience this number has to be change in this area this is because of the meeting in reading everything that's according to the area so we can just simply give it one classes plus it is 151 to call 19 which is in the range of 5 and I also just give it more color vessel true so what is this area because this is only one district this kind of analysis is more suitable for the base and they will analysis we will get more zones when you will do it for this area is missing because we did not have data assign here in this area they were buying subsystem a senior this is the area where people are extracting this no option region it's high but never did this is because of several reasons and one of them is the flat topography and chinois verticals thank you very much I hope this video was sufficient to arrest and drastic index and the only thing which to understand is like you need to work out the rates and widths all other processes quite station thank you very much

Channel: Integerated Water Resources Management

Views: 5,116

Rating: 5 out of 5

Keywords: DRASTIC, GIS, Groundwater, Vulnerability

Id: iXEwcOlZr10

Length: 35min 11sec (2111 seconds)

Published: Tue Jun 09 2020