Generate stream order in QGIS using DEM || Create a stream order map

hello and welcome back to another qgis tutorial here i will be creating a stream order map in qgis using a dem digital elevation model before we begin the tutorial we should have a clear understanding of an idea on stream order we have created a separate video with more information on stream order which you can get by following the above link so now let's get started first load the dem from which we want to generate revert and streams you can practice with the video by downloading the dem link in the description as well so to add the dem go to layer and add layer and then select add raster layer and then find this find the dem file you want to add and that's it so after getting the dem in qgis window let's check the crs in this type of analysis we need a projected coordinate system however we can see that the dem is already in projected coordinate system so what we don't need to convert the added dm to the projected one but if the dm you are using is not in projected crs we suggest you to convert it to the projected one so now further to that we will use saga to fill the sink in added dem to do so navigate to the saga and select terrain analysis hydrology then open the fill sink wang and lube from here and then this window will appear select the recently added dm from which we want to create the stream order map here save the field save the field dm to the location of your choice to do so go here and select save to file and then navigate to the location where you want to save your field dem and enter a name here i will be giving name as field dm and then click save over here after that uncheck both flow direction and water basin because we don't want them right now so after this press run button it could be a while depending on the size of the dem so friend we can see the fill dem and we can observe the change in elevation range as well okay so after filling the sink for a stream order navigate to saga and then to turn analysis channel select channel network and drainage basing select the file on the elevation that is field dem in threshold i will leave the default is value 5. you can decrease the value up to 1 for a more detailed stream or increase the value for only major streams accept the channel uncheck flow direction uncheck flow connectivity uncheck estral order uncheck drainage basin and uncheck junction as well because we don't want any of these analysis remember to check the channel okay so after that save the channel by channel save the channel data by clicking here and then on save to file after you have found your destination location give the file name and save it like this and press run it could take some time depending on the size and the resolution of the dm the higher resolution dm with the larger spatial area coverage will take a longer time so friends now we can see the streams now let's have a look on attribute table first right click on the properties of newly generated channel and select attribute table we can see the we can see the selection id to length here the stream order is described by this order over here we can see the order value of individual stream over here let's build a proper stream order map layout now for this check on dem and right click on dem and click on properties navigate to the symbology tab and under the render type pick single band pseudo color here in in interpolation choose linear and then choose your favorite color ramp and after that click on classify and then click ok so after this let's let's add a 3d effect or more technically a hillside effect for proper visualization of the topography to do this go to raster and analysis then he'll said select the dm in input layer and then click run after some time you can get a hillside over here so now move it to the top layer order just down to the stream and then go to wheel sets properties and in transparency section decrease it to 15 percent and click ok as a result we can see some 3d effect here now why not label the stream with their order number and change the color of each stream as well so to label the stream over or stream order go to channel click over here and select properties and go to label click here in no label and select single label in value click over here and select order as in the attribute table the order represents the stream order number in size i will be giving six value because i don't want larger font you can even customize more from this window for now i will click here in apply and finally okay so friend we can see the label in every individual stream here so now let's set the unique color to every stream error for this right click on the channel and go to properties and symbology over here select the categorized and in value again select the order and click here to classify here we can we can change the width of the stream order also it's per the requirement for this double click here and change the value in width it i will give value 1 okay even we can change the color manually from this window for this click on color and select the preferred one and finally press ok so let us repeat this step in 5th order as well double click on this line here and change the color from here like this and change the width from here like this and press ok and after customizing h for the requirement press apply and finally okay here order of layers would be exactly like this if not arrange the order of the layer from here by simply simply dragging up or down so after planning everything here let's move to the print layout for this select project and then go to the new print layout here you can give it a name i will type stream now click ok this new print layout will window will pop off now go to add an item select add map and left click and hold on top left corner and move the cursor to the bottom right corner then release we will get a map here finally determine the extent size of the map layout we can select and move the whole item by clicking here let me fix it to this size so after this let's let's fix the item to the map by fixing the scale of the map okay so go go to item properties and on scale type the matching one the less value means more detail you may try multiple time to find the perfect scale like this and if you are a beginner to qgis it may take some more time okay so after this if you click over here you can move the map only here let me move the map to the perfect location so now let's add a north arrow for this go to add item and click on north arrow after that to your preferred location left click and hold and drag on either side according to the preferred size of the north arrow for scale go to add item and select scale bar and repeat the same process and for legend go to add item and click on add legend here we have unnecessary legend also so modify is the need here select the legion in the item and in item property scroll a bit down and you will find legend items uncheck an auto update here now remove the unnecessary legends for this hold ctrl and select all the item except the channel and after selecting all the item except the channel click here in red minus sign you can change the name of your preferred one from here just double click here i will be typing stream orders now let us add a grid also for this select map in the item scroll down and you will find a grid and then click on grid here after that click on green plus button here and add on and on grid 1 select modify grid here in the interval give the value on x and y at least division by 20 of the skill value to know the skill value go to back and scroll up here in the main properties you can see 25 000 so back to grid here in x value give the value divisible by 20 of the scale value that is 1250 and same in the y value you can change the value here like this let me put thousand on x and thousand one y but you cannot change the value much okay for example if you type one lakh or only if you type hundred you want to get a desired and uh here you can you notice the gapping of x and y in the image in it depends upon your preference okay after this scroll down find the draw coordinate and check on draw coordinate here we can see the horizontal coordinate taking lots of space on the both left and right part so let us change them to vertical for this go to left and in horizontal select vertical ascending again go to right and in horizontal select vertical ascending okay after this we are ready to extract the image file for this go to layout and select export as an image and select the destination and give the image a name i will be giving final image and then click on save now this window will appear and in export option give the export resolution here i will be i will keep 300 dpi default as 300 is a decent dpi for a good quality image and click on save and we are done here we can see the saved image okay keep in mind that the stream order we prepared is of straw order that's all uh hope you enjoyed the video for any sort of problem you can comment in the comment section like and share the video subscribe the channel for the best qgis tutorial and selecting and lectures in special analysis have a good time happy learning

Channel: QGIS WORLD

Views: 3,370

Rating: 5 out of 5

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Id: -fr9V9hj_IM

Length: 13min 31sec (811 seconds)

Published: Mon Mar 29 2021