HRUweb Tutorial
The WebHRU is a web tool which was developed to derivate hydrological response units (HRU) online. It was implemented in Python and calculates HRUs according to GRASS-GIS algorithms.
Fragen:
- Bezeichnung der 2. Unterteilung: Workflow oder Parameter Setting?
- Legend description am Anfang?
Contents |
Starting WebHRU Tool
Link to HRU Tool: http://intecral.uni-jena.de/hruweb
Do user login:
Description of user interface:
- map window
- table of layers (set visibility, zoom in or remove -> see section "Legend") [set link to legend]
- process log
- download browser (provides data layer as raster or shape file)
- processing step description and manual input/settings
- The uploading process is always shown in the Server Processing Log:
Step 0: Data Preparations
First of all, open your input data in a GIS and check them for:
- completeness: At least DEM and gauges are required for delineating HRUs. The rasters of landuse, soil and geology are optional input.
- projection: The coordinate system has to be metric (like e.g. UTM) in order to enable distance calculations.
- layer extend: The layers should have at least the size of the catchment. A base map could be helpful.
| Input data | Description | Format | |
|---|---|---|---|
| DEM | Raster of Digital Elevation Model | Tiff (.tif) or .zip-file | mandatory |
| Gauges | Layer of gauging stations | .zip-file | mandatory |
| Landuse | Raster of landuse | Tiff (.tif) or .zip-file | optional |
| Soil | Raster of soil | Tiff (.tif) or .zip-file | optional |
| Geology | Raster of geology | Tiff (.tif) or .zip-file | optional |
Step 1: Uploading Input Data
Aim: Define base map and upload input data
Parameter Settings/ Workflow:
- At first, decide which map source should be used as the base layer (default: OpenStreetMap):
- Then, upload the required input data (required data described in Step 0).
- The projection of the map will be set automatically on the basis of the input data.
- For starting the uploading process, click 'Run'.
Results:
- The overlays 'Upload' and 'Gauges' are created.
- //Note: If the 'Upload' or the 'Gauges' layer are removed, the whole uploading procedure has to be done again by reloading the page.
- They can be downloaded from data browser.
- File:Databrowser step1.png
When finished, click 'Next'.
Step 2: Data Setup
Aim: Define area of interest for delineating HRUs
Parameter Settings/Workflow:
- To zoom into the area of interest, right-click on the 'Upload' layer and choose 'Zoom to layer extend' or use the magnifier to do so.
- The gauges are shown in light blue dots. The area of the gauges is marked automatically in a red bounding box.
- //Note: The red box marks the maximum extend. Data outside of this extend are not delineated.
- If the red bounding box does already represent your region of interest, you can skip the next step and click 'Run'.
- If you want to specify your region of interest, click on the box symbol
in the GRASS-HRU MAP menu.
- By clicking on the symbol, another overlay layer called 'Region' is created and the automatically set bounding box is now covered by a blue box.
- This blue box represents the area that should be used for delineating HRUs later on. Due to computational reasons, its extend should
- be fitted to the gauges' positions.
- Fit it by clicking into the blue box and move it at the blue crosses.
- In order to shift the whole box, drag&drop it by the blue cross in the centre.
- In order to resize the box, use the cross at the side.
- //Note: The 'Region' layer can be removed without problems. To do so, right-click on the layer and choose "remove".
By clicking on, the region layer can be restored again.
- //Note: If the extend of the blue box is chosen too small, important parts for delineating HRUs could be left out which makes the results unusable.
Results:
- A 'Hillshade' overlay is created.
- The hillshade layer can be downloaded from data browser.
When finished, click 'Next'.
Step 3: Data Preparation
Aim: Preprocess the DEM by filling its sinks.
- If the DEM was already preprocessed that way, no sink filling is necessary.
- Otherwise, it is recommended to do so in order to prevent lack of data.
Parameter Settings/ Workflow:
- Choose "Filling" (default) or "No filling"
Results:
- A DEM with filled sinks is created.
- File:Overlays step3.png
- File:Filled dem.png
- Single maps of sinkless elevation, slope and aspect can be downloaded from data browser.
- //Note: If filling fails, no maps for slope and aspect are available.
When finished, click 'Next'.
Step 4: Reclassification
Aim: Reclassify terrain attributes.
Parameter Settings/ Workflow:
- In this step, the class ranges of slope and aspect can be reclassified and renamed.
- In order to change table entries, click in the concerning field and type in the desired value.
- "Old": lists all existing class ranges
- "New": assigns IDs to classes
Result:
- The reclassified layers 'aspect' and 'slope' are created.
- The reclassified maps of slope and aspect can be downloaded from data browser as well.
When finished, click 'Next'.
Step 5: Waterflow
Aim: Define resolution of the stream network/ river system.
Parameter Settings/ Workflow:
- With each subbasin, one river segment is created. In this step, the maximum number of cells (pixels) for a subbasin of the smallest size has to be specified.
- File:Eingabe der pixelzahl.png
- example 10.000
Results:
- The layers 'Streams' and 'Subbasins' are created.
- You can download a zip file of stream network + subbasin layer from data browser
When finished, click 'Next'.
Step 6: Outlets
Aim: While creating the subbasins, the gauges' position can differ from the stream network.
- Check the gauges' position and decide which gauges should be considered.
Workflow:
- First of all, use the drag and drop mechanism to change the visibility of the layers in the layer view (legend no. X).
- Order the layer of gauges on top, followed by the layer of river network.
- Open Google Earth and zoom in to the gauges. Now use the gauges' position in Google Earth
- as a reference and relocate the gauges in the map of your results.
- Now the tool for relocating gauges had to be activated. Click on
in the legend to activate it.
- In order to relocate a gauge, click on a gauge and drag it to the proper river segment.
- //Note: If a gauge should not be considered in the further delineation of HRUs, just drag it out of the blue bounding box.
(zoom)
Legend
The layers can be edited in overview in the top left. By right-clicking on the overlays, the layers can either be zoomed or removed. By using drag and drop in the overlay list, the order of layer visibility can be changed.
== How to choose the best settings for ranges, HRU size+amount ==
