ArcGIS T11: How To Calculate Basin Average Value From Raster Data Using Zonal Statistics

hi there welcome back so today i'm going to show you how to calculate basin average value from any uh specially distributed data set for example if we have any rest data for precipitation if we have any temperature gridded data or raster data if we have raster data the basic thing we have to even calculate the vase in average value right we have some kind of uh graded data for example we have the dem data for this case so if you want to calculate the average value based in average value for any specific watershed so how can we calculate that one so that is very important thing to know right in hydrologic calculation sometimes we use a lump model for example heck a sms model it is a semi-distributed model sometimes you want to run this model as a lump model so for that case you need to write calculate the vase in average precipitation based in average temperature based in frs everything every parameter if you want to activate your et means vapor transpiration module then you need to calculate the vaseline average value and if you are going to run the model as a distributed model if you have grid then you have to calculate the graded input parameter but most of the cases for simple run people just use lump model and in order to do that you have to calculate the vase in average value so we have option here i'm going to show you that that is called journal statistics and we can do the same thing i have the code in r and i have the code in python that can do the same job so if you are familiar with gis then you don't need to write even any programming language so it will automatically do that and if you have many files for example if you have time series files for uh several hundred file right so you have to do the same thing by clicking one by one but if you don't want to do that there is an option uh in the future video you'll see that we'll build a model what is called model builder right so that will do the job for you it will look through the directory or the folder where you have your input files and it will just do the job for you and you have to do the same thing right so i'll show you that definitely i on i have one video uh it is like a one year more than one year old so it is in the heck asms playlist where i already demonstrated that one how to create base in average precipitation for a case in this model but today i'm gonna just uh show you at the part of this uh full package of hey ksms tutorial that how to calculate basin average values or from any roster since we have the dem value for our watershed right buffalo sun just into watershed located in houston texas so we are going to calculate the vase in average so for calculating basin average value what we need we need only the watershed based on that watershed it will calculate the value let me just quickly share my screen and uh describe you what we are going to do right now so here it is right we already have idea about that we already calculated the hill shade we calculated even flood inundation map you have an idea about that one so now i'm going to turn off that layer okay and then i'm turning on that watershed layer so these are the hawk watershed not hawk 10 right so we have even hawk 12 as well we can we can calculate hawk 10 as well we have both watershed right for example uh if i wanna open that say attribute table so what you're going to see here see it's nothing but we have hawk 8 hawk 10 and hawk 12 okay and we have this name of this watershed okay separate watershed so what we are going to do we will calculate the average elevation right for example it will give you we are getting shape area right shape area in terms of we don't know the unit okay do we know that no in order to calculate the area in kilometer square or in square mile we have to okay let me just area sq kilometer okay you want to calculate area in kilometer square so what we have to do just click double and we're done okay so once you're done with that one just right click here and then select calculate geometry and it will give you different options right area this area and perimeter is giving you that one and here you can select the square feet it is in square feet probably by default because the unit is in state plane and if you wanna change it to square kilometer there and click okay so it will calculate the values in terms of the square kilometer you can see that okay so we have the area now what we're going to do we'll even calculate we'll add one column and we'll calculate the average elevation value right this is this is basically the shape files but what we need we need to calculate the average elevation value for this shape right we have how many how many shafts we have here you can calculate that one okay so we have like a 29 28 because it is starting from one so you have 28 sub watershed right hawk 12 sub watershed so we already have idea how to calculate the area of any uh shape file okay and then we are going to calculate the average elevation value for this watershed for this subwater shed for this is of this so we'll have even 28 average elevation value so if you want to even calculate the precipitation so you have to do the same thing it will give you the average specification value for this watershed because if you want to run any sms model or any other model if you i want to import that time series for missing average at outlet of any sub order set we have to calculate the average right basin average value for this one even though since the basin is not that big so the distribution of rainfall it won't be varying that much so you can use one single value average value okay so that is even reasonable that's why you have to know the processing so how can you do that if your geoprocessing extensions are already turned on if not then click customize and then go to extensions and turn all this on then what you'll have click on value is basically that journal statistics it is called the journal statistics it will calculate all the statistics mean median average maximum minimum everything it will give you but out of these values will use only the mean value because it is the uh basin average value it will use that area you can even calculate by yourself because now we know the area right if you know the area and you can calculate the total value how can you do that we already have idea about that we know the cell size right of this grid you know that cell size is 97.44 right and 97.44 so you can multiply that cell size and you can calculate how many cells we have for this is of this basin then you will have the total amount of that data and then you can divide that one by the area so you'll get the base in average okay so here it is if you click on arc toolbox and then here spatial analysis tool and after that you have to go to journal c we already calculated right we already used that tool math algebra we already calculated uh values or contour using surface and now we are going to even calculate that one the last one journal statistics if you click that expand that one you have that different options general geometry as table general histogram it will give you the histogram for that basic average and then we are going to create that values of the statistics mean the mean median and the maximum minimum everything as a table and out of this table will convert it to excel right excel file so that is our goal because if you want to use that value you need to even export that as excel file and then we can convert it to csv right so that's why i'm selecting this one journal statistics are stable but if you select journal statistics it will give you only the statistics but you can't even export that one so once we have the table we can export it so that's why i'm selecting this option i can play with every everything and then you can see what it is giving right so double click on that statistic so it is asking that input raster so which one will be our input raster so dem feet right or which one so we have the option here see it is the zone right based on statistics will be calculated means it is the feature or it may be even raster since we are going to calculate the basin average so we are passing that basin that one right buffalo sends us into watershed and then journal field which field you want you have to specify let me just open it again and you can see which field you want based on the name right this name even the id this hack id is same this id may be same for few of them if you calculate that hawk 12 definitely hack 12 is different for each one so to be on the safe side you can even select this name field okay if you select the name field it will give you that value based on the name so okay just this one hark 10 name that will be our field so it will calculate the value based on the name because if you have the values based on id you it may be misleading you may not understand where it is but if you know the name of the watershed or subwater shed and if you have the value then it is very convenient to even now interpret right so that's why hawk 10 name every time you want to select anything go to go back to that attribute table and open that and see which one you need so you have access to everything so hawk 10 name and input raster which one will be our input raster that dem fit that we already have converted right the vertical unit you already change it from media to feed and horizontal unity already converted from geographical to state plane and now it's asking where to save that since it is we already have the default geodatabase it is changing there so zonal stat okay general step that's okay it will create and see in that field what will be the type of the statistics if you select that one if you want to select only mean it will give you only the mean value that is the base in average okay we call it base in average if you want to select all it will give you mean maximum minimum and range minimum to maximum and then a standard deviation and what will be the total sum and then min max and then mean standard deviation and mean max mean so these are the statistics it will give you everything every possible statistics it has and then you have the description here if you select all then what will be the output and if you select mean what will be the output and you have the description there so that is the benefit of using gis we have this help menu there on the right side of this window so i'm going to select all and then if i click ok then it's going to calculate the ways in average right we can calculate it manually but since they already have the option so we can utilize that one so here it is we have that as table if i want to see whatever we have inside that one see it's there and based on that value we can easily see that we have the name hack 10 name right and we have this because we have common names some common names so it is just interpreting as eight and then see that count means these are the cell number the raster value and that is the area it's giving maybe in square feet it doesn't matter and then we have the minimum value because we selected that elevation right and then we have this selecting the minimum and maximum it based on the location see the minimum value for the lower part is minus 22.96 so it is giving the sixth digit and we have the maximum one so next term is two zero six we know that minimum is this for the entire uh area and it is giving us the range difference between this min and max and that is the mean value for that subwatershed because it is located on the highland and it is right so that's that and the standard deviation and some of these values we have so if you want to even export that one how can you do that we have the option right there we can even convert so go to cartography or conversion okay conversion and then excel if you want to export it to excel it is that there right excel to table no we are going to convert from table to excel so select that one and import that table journal statistics and then it's gonna save it's gonna create there i'm gonna save it to uh lab two okay tutorial inside lab2 or outside of okay if i select that one let me just go back here okay i'm going to select that name of the excel file jonal statistics journal stat okay journalist yet and then it will be xls file see it's just converting and it's done okay let me just go back to that tutorial and maybe it's there okay journal statistics is there can you see that yeah if i double click on that it will open the same table or value but in terms of excel sheet now we can even manipulate anything we can even create table we can paste this table right in your report or anywhere you can use that and if you have other information to add you can add that you can even change the type and options you have you can do that you can manipulate so this is how we can even calculate the journal statistics but this is the way we can do and i just demonstrated that way but if you have other information that sometimes we are not going to calculate general statistics for dem because it is misleading uh we just only calculate the meteorological parameter like precipitation temperature humidity and if you have any shorter radiation long wave radiation for the calculation of of other uh loss you have transpiration loss right if you want to have an add of the pen men montage if you want to calculate the pen men montage right if i put transportation loss then you need different types of values and once you are done with values we have to calculate the base in average using this one so that is the way to calculate vase in average so practice by yourself in the next tutorial i'll show how to download the precipitation value and even how to do some calculation we'll download rainfall data right that are within our study area we'll find the gauges and we'll download that and we'll process and you'll learn because we are just going deeper into right from very very shallow level to the defense side of this tutorial and to the more specific objective we have because at the end we are going to run a model hydrologic model so these are the pre-processing and how to create maps and other information you already have idea about that one and we'll even use different module but for the sake of this course i'm just following the the guideline we have and you can just repeat all this process and you will even complete one grad level course or basic gis course and you will be i think medium level expert on that one okay in the future videos i'll show the advanced level so that is another issue but that will be outside of this course okay so that's it i'm gonna finish off here and if you have any query or question let me know and i'll be happy to answer your question i think if you follow exactly what i'm doing here you won't face any problem unless it is related to your software package or anything else so good luck for you and thank you very much for watching and see you in the next tutorial

Channel: Md Arifur Rahmahn

Views: 71

Keywords: basin average rainfall, arcgis, zonal statistics, thieson polygon

Id: yvfLbtptSMI

Length: 16min 59sec (1019 seconds)

Published: Tue Sep 07 2021