Complete HEC-RAS 2D Flow Modelling Tutorial in 14 minutes| Unsteady Flood Model |No GeoRAS and TIN

hello everybody now in this tutorial we'll be learning about the two-dimensional flood analysis in haikras so let's get started we are not using the higgs duras or the tin for analysis we'll be using the ras mapper so first of all let me create a project file go to file and new project give the name then uh the system snapper the most important thing before using ras mapper is we have to assign the projection system appropriate precision system which is very important so go to tools set projection of the project and you just give the location of that projection file you can easily find a projection file in the gis files or you can download the projection file make sure it has the extension dot uh prz so okay i have this prison system uh wgs1984 utm june44n after that click on ok so now we have set our projection system the next thing what we want to do is we want to have the terrain uh of the area which we are working on so in order to develop the terrain just first of all select the terrain layer okay then right click on it and there are two options either we can create a new rasterian or add the existing rash terrain uh so first of all let's create a new raster chain okay so for that uh click on this plus sign and go to your location where you have that uh the dm file okay so i have here okay so it appears you click create now the terrain is being created okay it won't take much time it depends upon your day maybe the day is very large it will take much time but if the game is small then it would be completed very soon okay let's close it the next thing what we need to do is we want to add the map layers right so we want to add google earth image of our map layer so right click on the map layer and add wave imagery layer so you can see uh google satellite okay double click on it there you go you can see the google satellite image of the selected region this is automatically zoomed to dame area so this is the area i'm working on okay so here's the river uh there's the river flowing the settlements the hills okay there are two ways to insert the river geometry uh you can directly close the region within the rash mapper or you can go to geometric editor so there is geometric data and so you can see the geometric data this terrain map appears automatically or you can try to see google earth image okay here you go so it's there so there are two ways to enclose the boundary so we need to enclose the river area in 1d we used to digitize the bank lines center lines and create the cross-sections and analyze but in two-dimensional analysis we enclose the area okay we consider that the river flows in two direction so for that we need to create 2d polygons go to 2d flow area you can click there and start marking your flow area say i do like this you just keep on enclosing your [Music] river area so it depends upon what is the area or to what extent you want the result so there are several factors so give the name say river what you should be aware is that always enclose the potential area of the river inundation and not more not less because if the uh two-dimensional area is larger then there will be more polygons there will be more sales and the computer needs to perform analyzes in each and every cell so it consumes time and the result might not be stable so for that purpose make sure that you enclose the river area a lot more and not less so this is how you uh enclose the river area so next step what you do is you click on this edit 2d flow area we are going to area and we're going to create the mess so you go to generate computational points okay so spacing is like so what what is the dimension of the cell you want it could be say 50 by 50 or 100 by 100 it is the dimension of the individual cell so the smaller the cell the finer the result but understand that smaller the sale size means it there will be greater number of cells and it would take a longer time for the computer to process so uh you have to add the spacings appropriately as per your study area as per the requirement so for this purpose i am just trying uh 70 by 70. and leave these this shift zero drop points to just as it is and click and generate points into the flow area okay so you can see this uh this mesh contains 571 cells of the given size okay we click in okay keep in mind that greater the number of sales means it would take more time for computers to analyze because uh the analysis works by working on every sale so greater the number of cell the more time it takes and also the the finer it could be so uh it's all up to your choice okay so the next step we do is we apply the boundary condition okay go to this boundary condition icon and start clicking so i'm clicking here okay double click on your over give name so this is my upstream so i'm giving it name of stream okay and in the downstream we'll be giving another boundaries okay click here and just like this double click finished okay let's give a name downstream okay so file you save the geometry file okay name any file say uh jio or whatever you want okay i've already told you that it could be done within russ mapper also not a big deal okay after we are done with the boundary conditions let's go to rust mapper and when you check on geometries and when it's a 2d flow areas there you go that our flow area has been enclosed okay this is our uh working area and these are the sales you can see them right so if you want to edit the flow area you can edit it uh just go to perimeter right click on it and edit geometry so by doing that you can add new points or you can you know move the points you can enclose as per the necessity make sure that uh you always space for the river to inundate okay and don't give unnecessary area because that would increase the number of cells and it would take much time for the analysis so uh that's how you do after you're finished just right clicking here and stop editing and yes okay there we go so our study area has been enclosed so the next step what we do is uh we define the boundary conditions okay for that go to edit and go to one city flow data see that two good the two conditions appear automatically one is downstream and upstream in the upstream we want uh the flow hydrograph number so it depends upon what sort of data do you have if you have the stage hydrograph or normal depth or even rating curve in upstream then you can choose any another option uh if you have the flow hydrograph then you can go to the flow irograph okay so i'm going to flow ideograph within the flow at a graph uh there's option of know applying the hydrograph so it's your choice what sort of hydrograph do you have one hour is for two hour autograph and you can give a time a particular time say 3 june 2020 an hour is zero zero zero and you can put some random values say 0 or 50 or 70 then 90 and 150 or something like that or 200 and 500 and if you interpolate the missing values then it automatically interpolates the values okay and the next step is we need to define the uh easy slope let's say in this case we 0 1 5 you can measure it you can plot the profile and measure it just for the sake of convenience i am using 0.15 as the value okay so this is our flow iograph for the downstream condition i will be using normal depth and say 0.05 something like that click ok and save the honesty data let's see on td and clicking ok so the next day what we do is we go to the last mapper right click onto this area and we compute the 2d flow area hydrogen table okay that table is created what we do next is we run the data okay to run just go to run go to on city flow analysis so in this install analysis you have to put the very same data the very same starting date [Music] that you had entered earlier so for that i have to check it here okay so hydrograph it's here the starting date is something like that okay 0 to june 2020 and starting time is 2400 okay ending time uh ending time is third zone 2020 and in time would be 1900 1900 okay the next step is selecting the appropriate computational interval so there are four intervals competition trouble hydra out of interval mapping out interval and detailed interval uh we focus most on computation interval and these factors these intervals decide the stability of the model it's all about the trying testing is all the hit and trial method you keep on trying with one condition interval and test the result then see whether the model is stable or not and accordingly change it for the sake of convenience i'm uh see using one minute an either order interval is in what time do we need uh that output so for that sake i'm saying one hour and mapping out interval is in what interval would it map the uh data so elevating one hour okay after all all the information is given just click on these options and click compute

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Id: ALtkCXdVS7k

Length: 13min 55sec (835 seconds)

Published: Tue Jan 11 2022