Kristina IsbergHere you will find some step by step tutorials for some basic WHIST procedures.
- C 1 Delineate new subbasins using the given topography data
- C 2 Delineate new subbasins using my own topography data
- C 3 Adjust forced points to river network
C 1 Delineate new subbasins using the given topography data
There are two ways to delineate new subbasins in WHIST from topography data.
- with so called "forced points"
- without "forced points"
Forced points are locations we want to coincide with subbasin outlets, e.g. hydrological features as gauging stations, lake or reservoir outlets.
Forced points must be adjusted to the river network of the topography data before they are useful otherwise the delineation of a proper upstream area of the point can not be developed. See HYPE set up tutorial for more information.
Instructions for the creation of forced points can be found here: C 3 Adjust forced points to river network.
When the forced points are generated or if no forced points are going to be used, follow these instructions:
- Go to HYDRO/Create and click on the "Edit" button in the new window
Under "grids" you can see which grids are used for the delineation and routing created. The GWD-LR river width (WTH) grid is here used as a mask to avoid subbasins to be cut along the centerline in broad rivers.
Under Parameters and options you can set a subbasin area limit for both usptream subbasins and the coastal subbasins (a smaller coastal area limit decrease the number of very broad and large coastal subbasins). For World-wide HYPE and the course model the limits were set as in the figure, 1000 and 500 km2 respectively.
Under Forced points file you can browse for the file you use for forced points. Here are the gauging stations adjusted to the river network according to instruction under C 3 Adjust forced points to river network has been used.
Save the settings and activate the button "Add tiles". If you are adding subbasins to already existing subbasins the "force add tiles" must be checked.
Click on Tile size and choose the size of the calculation window. Approximately 5-15 subbasin per tile is fine (so this is dependent on the previous settings).
Click OK and then click somewhere to add the first tile. Preferably where you have the outlets of the rivers. (You can also add tiles over the entire area from start).
Then click on start iteration button and after a while some subbasins will appear within the tile.
These subbasins are not all finished and to let WHIST search for the upstream areas for some certain subbasins you should:
- deactivate the place tiles button
- select the river outlets you are interested in
- click on the Edit 1 /Haro Id "set"
New tiles will then automatically be added.
Check the "auto add tiles" and start iteration again. Now the iteration will continue until the total upstream areas of the selected coastal subbasins are finished.
If you select the catchment you want to use for your model and then use the button Flip you will select all the other subbasins.
Use the kill button to delete the unnecessary subbasins.
If you view the Flow or Flownet you can see how the subbasins are routed.
Save your work, see Save
Now you can link other spatial data to these subbasins (elevations, SLC´s, etc), see 11. Extract and connect attributes to the subbasins and export a first output for a GeoData.txt file for HYPE.
You can also export different kinds of shapefiles (subbasins, flowlines, main river basins etc), see 12. Export shapefiles and tables
C 2 Delineate new subbasins using my own topography data
Read all instructions thoroughly and remember:
- There are just a few coordinate systems that can be used
- There are just a few DIR code systems to use so you have to adjust your data for this.
- The grids must be of BIL format.
See instructions: 2. WHIST requirements.
When you have created the gridded data you must set a link to the data within WHIST and inform WHIST about its properties. See the instructions 2.4.4 Load new topography data into the WHIST database
After the loading of the grids you can make a first check and try to view them within WHIST, see 6.3 Viewing grids/topography
A second test is to create some first subbasins to see that the settings are fine and that the grids are harmonized. If no subbasins appear or strange subbasins appear, e.g very small, there might be something wrong with the units or projections.
When you are able to create subbasins you can decide whether you would like to prepare subbasins tailored to specific hydrological features or not (these split points can be added manually afterwards also, if a smaller model). Go to C 3 Adjust forced points to river network if you want to prepare forced points. If no forced points are needed, follow the instructions in C 1.1 Create subbasins.
C 3 Adjust forced points to river network
The forced points, e.g. gauging stations, might have unsure coordinates in their metadata which might not correspond to the topography river network used. Before these forced points can be used for tailoring the outlets of the subbasins they have to be adjusted to the river network. See figure beneath.
Figure to the left shows how the position of the feature is adjusted to the river network (ACC/UPA grid in behind). Figure to the right shows how the subbasin delineation is tailored to get the subbasin outlets at the forced points.
PROCEDURE:
- Prepare a metadata table as in the figure. The bold headers are mandatory. Save this file as a tab separated textfile (ASCII file).
- ID: a unique number
- NAME: a name for the location (no space allowed)
- LAT: original latitude of the feature
- LON: original longitude for the feature
- DRAINAGE: Drainage area in km2 of the feature (if not known, write -9999)
- RADIUS: The limit of the search area in the same unit as the topography data used.
Example of a table, tailored for WHIST, with gauging station metadata according to the original source.
- Start WHIST and go to HYDRO/create/edit, see figure. Check that you are using the correct grids (DEM, DIR, ACC/UPA) and add a mask if there are locations to no adjustments should be allowed, e.g. within lakes, in the sea etc. Save and close window.
*Figure: How to check that correct topography database and method is used.
- Go to HYDRO/create or edit forced points.
- Click on the button "Add points from file" and browse for your tab separated textfile.
- Your table will appear at the top of the window. Check that you have the correct ACC/UPA grid, see figure beneath, and then click on the button "Auto Adjust".
- A new window opens where you select which column that shows the ID, drainage area, radius, if you want to use a mask where no forced points will be allowed. There is also a parameter called Accuracy, here you can give a floating value between 0-1. if you for example set it to 0,05 you let WHIST to search for the best point within the search window which match the drainage area with an accuracy of +/- 5%.This parameter can be used to decrease the spatial adjustment (the drainage area may be more inaccurate than the location). Click OK.
