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OpenFlowFlood

Hello ,I have to assign drainage sizes for natural drainage,but currently I dont have any data .Can i use Bathymetric data for that ?if yes How?.Also i have tidal data in excel format .How to add that in OpenFlowFlood?Thanks.

  • Hello Avikant Kamate,

    Yes, with OpenFlows FLOOD natural drainage network it is possible to assign cross-section types and parameters (cross-section height, top/bottom width, etc). There is currently no automated way to assign irregular cross-section position/elevation data to specific nodes, but it can be edited manually. You can derive the river cross-sections from bathymetric data, but that depends on what type of survey data you have access to. If the survey measured river cross-section batthymetry you can do it as described next. You must first construct your natural drainage network and assign default cross-section shapes based on Strahler order or drained area. For details on how to do it please refer to this video

    Once your Drainage Network.dnt file is ready, you can, :

    1) In Map (assuming your Drainage Network.dnt has been loaded on to the Map) click the "question mark" button on the map top-right toolbar

    2) select with the mouse which node you want to edit. This should be the one(s) you have bathymetry (elevation) data 

    3) a dialog on the right hand side of the map will appear identifying the Reach ID, Up(stream) Node ID and Down(stream) NodeID. 

    4) Take note ot the Up Node ID (e.g. 3892)

    5) Open the Drainage Network.dnt in a file editor and search for 3892. You'll find a <BeginNode> <EndNode> block where there is a keyword "ID      : 3892"

    6) Inside the same <BeginNode> <EndNode> block:

    6.1) Set keyword CROSS_SECTION_TYPE        : 3

    6.2) Remove the lines containing BOTTOM_LEVEL, BOTTOM_WIDTH, TOP_WIDTH, HEIGHT

    6.3) Add the following keywords N_STATIONS, STATION, ELEVATION, where N_STATIONS you set the number of elevation points that define the cross-section, STATION will be an array of values with the distance to the river bank (e.g. STATION    : 0.0 2.03 4.06 6.09 8.13 10.16 12.19 14.22 16.25 18.34) and ELEVATION is an array of values with the corresponding elevation values (e.g. ELEVATION   : 13.06 11.65 10.92 10.20 9.41 7.48 6.17 5.96 5.77 5.53)

    7) Repeat this for all the cross-sections you have data available. 

    Depending on the type of application, you may be able to construct the cross-sections in a different way. For the methodology above I've assumed you want to create a watershed model and then assign specific cross-sections with available river cross-section/bathymetry data. This type of simulation assumes the river cross-section is contained inside a 2D computational grid cell. If you are looking into doing 1D river/2D floodplain analysis then you may want to use the 1D/2D coupling tool or even look into constructing the 1D river model in CivilStorm or SewerGEMS and then couple it to FLOOD. 

    Regarding your second question, I assume your tidal data is water level observations. If so, this type of data can to be used either for tide model validation or forcing the water level at the open boundary. For the latter, you can read this article where you can also find information related with how to construct a time series file in FLOOD format. 

    Please let me know if you require any additional information. 


    Kind regards,

    Luis

    Answer Verified By: Yashodhan Joshi 

  • Thank you sir for the helpful information. I want to construct Drainage size for the Urban Flood Simulation.I can get information for drainge span size from site survey or from google earth but for the depth i have to asume something.any online data available for depth?Shall I follow same steps for constructing size for natural drainge in UFS?

  • For a urban flood simulation, it also considers the sub-surface drainage network (pipes), then the best would be to construct your 1D river/pipe model in CivilStorm (or SewerGEMS).

    If it's only open channel/river drainage (depending on the size of the river and the area of interest) you don't need to run a Urban Flood Simulation, you can just setup a simple MOHID Land simulation.

    Taking into account that you don't know the depths of the cross-sections, the best you can do is follow the same steps as for natural drainage and assume a certain shape (e.g. trapezoidal) where you set the top and bottom width, and set a specific default depth for the nodes and try to calibrate the model varying the shape, widths and depth of the cross-section. 

    There are several sources available online that have bathymetry and topography data, but most likely the resolution is not good enough (depending on the location you're trying to model). 

     If you can share some more details of what you're trying to achieve I might be able to point you in the correct direction.

    Kind regard,
    Luis

  • Hello ,if I model natural drainage sizes in sewerGEMS ,then i have to give inlet locations for coupling with OFF ?