8
votes
Accepted
Basin creation GRASS vs. flow direction
The problem was the parameter "allow only horizontal and vertical flow of water".
I really don't know why this is set by default in QGIS/Processing!!! damn noob error!
- 2,628
4
votes
Accepted
Selecting point to obtain water basin leading to it
Having fiddled some more with the subject, I've come to find an answer to this question and will follow up on it in case someone finds themselves in the same situation.
First off, I have run the ...
- 674
4
votes
Accepted
Drainage basins ignoring lake
Through discussions and research, I have figure out that the processes I have used simply do not identify the lake as being a lake and "simulate" a stream flowing through what the DEM identifies as ...
- 674
4
votes
Accepted
Does r.stream.basin still exist? GRASS-QGIS2.18.7
The module r.stream.basins is an addon:
https://grass.osgeo.org/grass72/manuals/addons/r.stream.basins.html
In order to use it from QGIS, you need to have the module being installed in the ...
- 12.9k
3
votes
Accepted
QGIS: How do I combine/summarize information from several attributes to one specific attribute?
Using a sample data (below image):
Start the Field Calculator and input an aggregating expression: sum("TD", group_by:= "NEXT_DOWN")
Then all the rows which share the same ...
- 30.5k
2
votes
drainage basin for whole lake QGIS 2.18.7
The GRASS watershed algorithm, by design, continues to route water flow across lakes (or any other flat areas or depressions). It stops when reaching either the edge of the region, or a null cell.
...
- 15.5k
2
votes
Accepted
Expression into the raster calculator to invert DEM
I would subtact the last pass and the first pass elevation if you want the height. You could also possibly add a constant (e.g. 100) in order to have positive values but this is more an esthetic ...
- 49.4k
2
votes
Can QGIS produce Stage Storage Plan?
Yes, QGIS can produce a map that looks like the one you included, as well as the data tables on the side. It should be quite a simple task:
Overlay elevation layers on top of a satellite image
Set up ...
- 24.5k
2
votes
Accepted
Extract polygon from stream line
If you insist on not using a DEM, you can use trace upstream from utility network analysis toolbar, and then create an convex hull of the selected network using Minimum Bounding Geometry.
But the ...
- 11k
2
votes
Accepted
Obtain channel/stream network from a DEM in QGIS
Some recommendations for extracting drainage networks with SAGA. I guess the first thing you do is fill the dem with Wang&Liu.
In some cases the result depends on the minimum slope you define. ...
- 1,284
1
vote
Accepted
Basin code in Google Earth Engine
If you want to know the HYBAS_ID of a specific basin according to its geographic location, first add the dataset to the map:
var dataset = ee.FeatureCollection("WWF/HydroSHEDS/v1/Basins/hybas_7&...
- 1,225
1
vote
How to isolate cooling influence of green roofs from land surface temperature data?
There is a lot to digest here, and i am not convinced that a watershed analysis is appropriate. I don’t know much about the cooling effects of green roofs on the surrounding land surface temperature, ...
- 66
1
vote
Obtain channel/stream network from a DEM in QGIS
Generally there are three main steps to creating a channel network.
Hydrologically controlled DEM
Catchment Areas
Channel Network
In more detail
Hydrologically controlled DEM
Use one of the Fill ...
- 3,815
1
vote
GRASS 7.8.3 problem with r.watershed and r.water.outlet
Are you sure that the drainage point lies exactly on a stream line? Zoom in close to the streams raster (from r.watershed) and get the X-Y coordinates of the center of one pixel on the streams line. ...
- 15.5k
1
vote
Generating Basin Layer Using Hydrology Tool gives ERROR 010067
Error 010005 is saying is that your file is too big to handle, and at some point ArcGIS ran out of memory. Some general ways one can deal with too large of rasters are:
Parallel processing (see @...
- 2,362
1
vote
Seeking outline/boundary (shapefile) of Ganges river basin?
The Global River Basins data at the WaterBase site looks like it might be useful. The big downside I see is that the shapefile only has codes, no names. However, it seems to align decently with the ...
- 2,265
Only top scored, non community-wiki answers of a minimum length are eligible