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Attention

Before starting data download, it is necessary to set the project to EPSG:5514
How?

Data Download Tab (Download)

  • First, you must select the area of interest for data download

    • To download data within the current map view, select Compute inside window extent
    • To download data inside a polygon, select Compute inside polygon
      • This action will allow you to pick a polygon from the project in the dropdown below

  • Next, you can choose which data to download

    • To download both land use data and hydrologic soil group data, select Land Use and Soil Groups
    • To download only land use data, select only Land Use
    • To download only hydrologic soil group data, select only Hydrology Soil Groups

  • To start the download, click the Download button

  • To stop the download process, click the Abort button

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Intersection Tab (Intersection)

  • In the Select Land Use layer dropdown, choose the land use layer

    • If it was successfully downloaded in the previous tab, it will be set automatically
    • If you wish to use your own layer, it must contain an attribute named LandUse_code with integer values

  • In the Select Hydrology Soil Group layer dropdown, choose the hydrologic soil group layer

    • If it was successfully downloaded in the previous tab, it will be set automatically
    • If you wish to use your own layer, it must contain an attribute named HSG with integer values, where
      • 1 represents group A
      • 2 represents group B
      • 3 represents group C
      • 4 represents group D
      • 0 represents water bodies

  • Start the intersection by clicking the Intersect button

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CN Layer Creation Tab (CN)

  • In the Select Land Use and HSF Intersected layer dropdown, choose the layer resulting from the intersection of land use and hydrologic soil groups

    • If it was successfully intersected in the previous tab, it will be set automatically
    • If you wish to use your own layer, it must contain attributes named LandUse_code (integer) and HSG (integer)

  • The line below shows the path to the CSV file for CN value conversion

  • To choose the location of your own CSV file, click the three-dot icon next to this line
  • To create the CN layer, click the Create CN layer button

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Run-off Volume Calculation Tab (Run-off)

  • In the Select CN layer dropdown, choose the CN layer

    • If it was successfully created in the previous tab, it will be set automatically
    • If you wish to use your own layer, it must contain an attribute named CN2 with decimal values
      • It may also contain an optional attribute named CN3 with decimal values

  • In the Initial Abstraction Coefficient field below, you can enter a custom initial loss ratio coefficient

    • This can be chosen in the range 0.1 – 0.3

  • If you wish to calculate run-off volumes using design rainfall depths from the rain.fsv.cvut.cz service for various return periods, select Use rainfall depth from rain.fsv.cvut.cz

    • Then choose the desired return periods via the checkboxes in the Select Recurrence Intervals section above

  • If you wish to calculate run-off volumes using your own design rainfall depths, select Define your own rainfall depth [mm]

    • Then enter the values in millimeters in the field below
      • To perform calculations for multiple depths, separate them with a semicolon ;

  • Start the process by clicking the Compute run-off button

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