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.
Contents |
Starting WebHRU Tool
Link to HRU Tool: http://intecral.uni-jena.de/hruweb
Do user login:
Description of user interface: [FIGURE labled with numbers]
- 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
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
At first, decide which map source should be used as the base layer (default: OpenStreetMap):
Then, upload the required input data for HRU delineation.
The projection will be set automatically on the basis of the input data.
For starting the uploading process, click 'Run'.
The uploading process is always shown in the Server Processing Log:
The overlays 'Upload' and 'Gauges' are created. [Figures 2x]
//Note: If the 'Upload' or the 'Gauges' layer are removed, the whole uploading procedure has to be done again by reloading the page.
When finished, click 'Next'.
Step 2: Data Setup
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'.
In order 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.
//Note: The 'Region' layer can be removed without problems.
//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.
A 'Hillshade' overlay is created.
When finished, click 'Next'.
Step 3: Data Preparation
The next step is to decide, whether sinks should be filled or not.
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.
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.
[FIGURE of results]
When finished, click 'Next'.
Step 4: Reclassification
In this step, the class ranges of slope and aspect can be reclassified. [FIGURE]
"Old": lists all existing class ranges
"New": assigns IDs to classes
As a result, the reclassified overlays 'aspect' and 'slope' are created.
//Note: By using drag and drop in the overlay list, the order of layer visibility can be changed.
The reclassified maps of slope and aspect can be downloaded from data browser as well.
When finished, click 'Next'.
Step 5: Waterflow
In order to define the resolution of the river systems, the number of cells (pixels) for the smallest size of a delineated subbasin has to be specified.
- example 10.000
- result layer: Streams, Subbasin map (a zip file of stream network + subbasin layer download in data browser)
When finished, click 'Next'.
Step 6: Outlets
Relocate gauges: drag+drop gauge layer -> top;
(zoom)
click on 
and locate gauges on the right stream segment
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.
