12
votes
How to go about creating points at river confluences?
The Intersect tool does not require two inputs. The help for How Intersect (Analysis) works says "Intersect can run with a single input. In this case, instead of discovering intersections between ...
- 8,555
8
votes
Accepted
How to go about creating points at river confluences?
"Could creating a geometric network solve the problem? (ArcCatalog > Geodatabase > Feature dataset > Geometric network). Junctions will be created automatically at the intersections of the rivers."
...
6
votes
Accepted
Missing/inconsistent River Thames map data in Overpass Turbo
The river Thames is too large to digitize it in one single Openstreetmap way element.
Therefore, a relation is created to group all riverbanks belonging to it.
You can query that relation directly ...
- 76.3k
6
votes
Accepted
How to get all rivers from OSM using Overpass?
You might find it useful to go to OpenStreetmap and zoom to your area of interest, then use the query tool (the Question Mark icon). You don't need to be logged in to use this.
Next, click on or near ...
- 20.2k
6
votes
Ways to determine winding topographic characteristics of a river
In the world of hydrology and geomorphology, there is indeed a metric that we use to classify/quantify the "curviness" of a river......sinuosity.
Sinuosity is simply a measure of the actual path ...
- 61
5
votes
Get rivers from a DEM raster
#You can run GRASS 6.4 commands in R using the spgrass6 package
require(spgrass6)
# connect to existing GRASS layer location using Mac OS X
loc <- initGRASS("/Applications/GRASS-6.4.app/...
- 341
5
votes
Buffering river but it came out as circle
I can make a guess at what has happened. Did you "set" the coordinate system of the river to UTM 50N or did you actually reproject it? If the original line was digitized over a map in Long/...
- 15.4k
5
votes
Accepted
Detecting automatically where rivers flow, directly into the sea or into another river
You can make an overlay (intersects/touches) of your river lines with a polygon representing the sea.
Before you can do this, you need a polygon layer representing the sea. Best use data for the sea ...
- 63.1k
4
votes
Get rivers from a DEM raster
Two free software solutions for watershed and stream delineation are the GUI software SAGA GIS (which can also be accessed through the sextante toolbox in QGIS) and David Tarboton's TauDEM. You can ...
- 31.3k
4
votes
Accepted
Split seamless polygon representing river banks into separate polygons using center lines
You can create a hexagonal grid covering the river polygons:
create table public.hexgrid as
with cte as (
select (st_hexagongrid(2.0, geom)).geom as geom --adjust the 2.0, the smaller the smoother ...
- 67.1k
3
votes
Accepted
Obtaining length of river upstream of points up to next point using ArcGIS Desktop?
RivEX does much if not all of what you are asking. For computing upstream length you would run the appropriate RivEX attribution tool to encode that into the network then transfer the lengths to your ...
- 42.6k
3
votes
Creating catchment from point using DTM raster in QGIS?
You can use Saga "Upslope area" geoalgorithm. You must install Saga and configure the path where you installed Saga inside QGIS in Processing->Options or Ctrl+Alt+C.
Then expand Providers->Saga,...
- 1,031
3
votes
Accepted
Finding upstream locations (polygons) using ArcGIS Geometric Network?
If you have set the flow direction as @ChrisW mentions then the polylines should be flowing in a source to sea direction. Place your flag at the green location then using the Utility Network Analysts ...
- 42.6k
3
votes
Accepted
Calculate Polygon Centerline with a LeastCostPath approach
I have spent many hours working on similar problems. I published a paper about it, even. In the Matlab toolbox presented there, I use the shortest path just like you're doing. In my experience, there ...
- 2,874
3
votes
Calculating Distance from Outlet to Dam(s) using ArcGIS Desktop?
If you are capable to populate tables of your data (links, nodes) accordingly:
I recommend networkx module, e.g. this tiny script computes distance to outlet for every node in network:
import arcpy
...
- 22.6k
3
votes
Help with Anita Graser's guide on making tapered rivers. River shapefile has "width" field but expression is not working
'< 10 km2 Fluss'
Is what is stored in Anita's attribute table. It is a string field describing the flow rate of the river.
If your width field is not a string, rather a number, then you need to ...
- 16.3k
3
votes
Understanding DEM of difference results in ArcGIS Pro
Millimeters are a good guess, but to be sure, open up both of the DTM properties and examine the results. Within the properties section, you'll see the units (meters, feet, mm, furlongs, etc) that ...
- 7,950
3
votes
Finding rivers from GeoTIFF files with GDAL
There are various implementations of watersheds and hydrology delineation using the the A* algorithm. For instance in grass gis r.watershed and python pysheds.
In this instance I recommend the grass ...
- 259
3
votes
Calculating minimum river width for a route within the river in PostGIS/Python
Difficult question, the holes are tricky.
One idea would be to start by getting the lines of the polygon. The difficulty is that you need to separate them to be sure to don't have both sides in the ...
- 2,405
2
votes
Ways to determine winding topographic characteristics of a river
I'm not a hydrologist, so I'm not aware of any metrics/heuristics that should likely govern your methods, but here's a stream-of-consciousness response for something that would be fun to try.
...
- 6,420
2
votes
Accepted
Problem with flow lines in ArcMap
The method that you used for 'excluding' data only applies to the symbology. So you are not really modifying the data, just what you see. I would create a new raster that removes the data from the ...
- 1,364
2
votes
Seeking outline coordinates of bodies of water (lakes, rivers, ponds) for country?
Pick one:
GLWD
SRTM Water Bodies
ESRI World Water Bodies
GLCF Global Inland Water
- 8,546
2
votes
Interpolate raster data using computer vision (OpenCV)
Simple inpainting algorithms generally use a smoothness heuristic, so this behavior is common. In some algorithms there will be an option to provide separate masks for inpainting (to be filled) and "...
- 121
2
votes
Accepted
How to perform an anisotropic Elliptical Inverse Distance Weighting (EIDW) interpolation in R?
I could apply an Elliptical Inverse Distance Weighting (EIDW) in R using the function gdal_grid of the gdalUtils package. I modified a little bit the gdal_grid help example in R documentation as ...
- 3,156
2
votes
Stream order from flow accumulation raster
Have a look at the GRASS addon r.stream.order. You can see an overview at here and more details in the main page
- 15.4k
2
votes
Distance from one point to multiple points WITHIN a shapefile
Use Point Distance tool: create a new feature class with just mouth point. and other points as a near features.
to calculte distance along a line, Use Linear referencing.
First convert the polylines ...
- 5,825
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
Calculate river distance to headwater for every pixel?
Flow length and zonal statistics should do the trick.
For Flow Length, you should calculate distance upstream and use a weights raster with your stream pixels set to 1 and all non-stream pixels set ...
- 979
2
votes
Accepted
Select a specific line length after and before a point
Try the "Service area (from layer)" algorithm in the processing toolbox. The "Vector layer representing network" will be your river network, and "Vector layer with start points" your point layer. The "...
- 27.3k
2
votes
Calculating percentage (or length) of stream network that is multiple channel streams using ArcGIS Desktop?
If I understand well, all your multiple channels create "islands" (portions of land surrounded by water, maybe it has a specific name) between them. Therefore you can identify the multichannels as ...
- 49.3k
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