Questions tagged [hydrology]
The study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability.
317
questions
2
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1answer
21 views
Counting upstream features based on flow direction line segments?
I am trying to find a way of counting how many lakes are upstream for each lake in my watershed. I feel as though I have the layers to accomplish this but am unsure of the tools/workflow. I have ...
0
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0answers
32 views
Merging river network features which should belong to same tributary of certain stream order in ArcMap without using Dissolve tool
I processed the DEM data through Arc Hydro to get the vector data of the river network. I recently tried to calculate the Horton-Strahler ratios and suitable flow accumulation threshold of it, yet ...
1
vote
0answers
24 views
Outputs of "Strahler Order" and "Channel Network and Drainage Basins" different despite same threshold
I ran the Strahler Order and the Channel Network and Drainage Basins tools both with threshold at 8 and using the same filled DEM. The results differ as shown below.
Strahler Order raster (only ...
0
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0answers
15 views
"Channel Network & Drainage Basins" works if the filled DEM is from "r.fill.dir" and not "Fill Sinks (Wang & Liu)"
I'm using QGIS Desktop 3.16.9 and was doing this video https://youtu.be/2Ub0c7Ss-T4.
The instructors used "Fill Sinks" and then the "Channel Network & Drainage Basins". When I ...
1
vote
0answers
42 views
Dissemination on a network
I'm looking to map the streams in which certain pollutants are found. These readings are points, and we assume that the water downstream of each point is contaminated. The mapping is not binary but ...
0
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1answer
13 views
Identifiying the levels for streams derived from DEM
I am using GRASS GIS and I have been able to identify the various water-flow channels / streams using the documentation from r.watershed.
Now I wish to identify the levels of the streams. For example, ...
0
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0answers
22 views
How to draw green space cooling extent from land surface temperature?
I am trying to find the cooling extent of green spaces within a city, meaning how far the cooling effect goes, within the context of urban heat island mitigation. I am trying to create polygons around ...
0
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0answers
78 views
Exporting very large map to image in QGIS [duplicate]
I'm trying to use QGIS 3.10.14 to create a hydrological map to edit (as a PNG) in image editing software. My purpose is recreational.
I've paired the Copernicus EU-hydro river network with ESRI ...
0
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0answers
39 views
Does most topographic data come with Z Coordinates, and if so how do you put them in a QGIS map?
I am trying to create a map of the rivers in a large catchment. When I try to 'fill the sink', mine makes it as if the surface is flat. My rivers are just squiggly lines.
It doesn’t look like it has ...
1
vote
1answer
49 views
Issue with delineation using dem because of a DAM
I have a high-resolution DEM which I use it delineate watershed.
I am getting the delineation like this
The main branch is not getting delineating till the source.
So I used a hillshade to check the ...
1
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0answers
22 views
How to check hydrological connectivity in flood fill techniques in QGIS?
I have a set of polygons (include their elevation levels), representing geographical areas. I want to check which polygons will be inundated if a flat flood level is given. Lets say 1m flood from sea ...
1
vote
1answer
41 views
How do you create upstream buffers at a specific distance from another polygon?
ArcGIS Pro / ArcMap
Licenses: Spatial Analyst, 3D Analyst
I'm working on a project in the Daniel Boone National Forest to create critical habitat areas in order to keep roadside pesticide applicators ...
0
votes
0answers
28 views
Column value as index in function
This comes from the solution of another question. I have a network of polylines representing a river network, where I am working to make a calculation at each point on the polyline, based on some of ...
0
votes
1answer
39 views
Interpreting ArcGIS flow accumulation tool results in urban areas
Using ArcGIS 10.8 I successfully ran through the following geoprocessing tools to complete a flow accumulation analysis of a USGS 1/3 arc second DEM of a portion of Houston, TX:
Fill --> Flow ...
0
votes
1answer
69 views
Error while running SAGA algorithms in QGIS 3.10.14-A Coruña
I've been trying to run several hydrological algorithms (Strahler, Fill Sinks etc) from SAGA in QGIS ltr and I keep running into the same error:
The following layers were not correctly generated.C:\...
1
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0answers
40 views
Representing Hydrographic survey in QGIS
I have a depth Layer (soundings) and I would like to represent the labels the same way as in a Hydrographic Map.
As you can see in the image bellow, we have this kind of representation in a ...
1
vote
1answer
82 views
Recursive calculations on a river network
I have a dataset that contains network distances along a river network. This dataset was created using Topotoolbox in Matlab, with the node and segment information exported. I've been working on the ...
0
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0answers
17 views
r.watershed: How does the convergence parameter and "AT"- lcp work?
I generated streams with GRASS GIS r.watershed, executed in RStudio. Now, I want to explain the functionality behind that function.
The GRASS- manual explains a lot here: https://grass.osgeo.org/...
2
votes
1answer
51 views
Methods for burning depressions (not rivers) in a DEM
I am using a 2x2m DEM to simulate runoff on a 2D hydrodynamic model. After a baseline simulation, I am interested in evaluating the impact of adding depressions in specific areas that may work as ...
5
votes
3answers
225 views
Hydrological Enforcement of culverts in QGIS
I work on a farm and we are in the process of developing a surface drainage program for individual fields. I am using QGIS 3.16 and the publicly available 2020 QL2 LIDAR flyover of Indiana, and my ...
1
vote
1answer
77 views
An application for measuring river length?
I'm aware of the coastline paradox and its application to rivers in that the measured length of a river depends on the resolution of the measurement.
Is there an application that calculates the centre ...
0
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0answers
45 views
Calculating monthly mean temperature from TerraClimate
I'm working on a hydrology project and need to obtain monthly average temperature data for a watershed. I'm using the TerraClimate dataset, but it only contains monthly average high and low ...
3
votes
0answers
101 views
QGIS Measure area below contour to develop elevation-area table
Is there a plug-in or methodology to measure areas under contours, which can be used to develop elevation-area tables?
I know you can create contours as lines from DEMs, but you need to convert them ...
2
votes
0answers
29 views
Efficient random access into rasters for hydrological analysis
I'd like to implement an algorithm to extract Strahler Streams as geometric lines from a predefined stream raster. I've done this using GDAL by walking across the rasters from the outlets or at the ...
2
votes
0answers
136 views
NA values as result from Grass functions (r.slope.aspect, r.sim.water) in R
As the result from r.slope.aspect I get a raster with only NA values. r.param.scale works, but doesnt generate dx and dy maps, which I both need for r.sim.water function.
Code snippet 1 (initialize ...
1
vote
1answer
171 views
Rainfall time-series to raster
I have a rainfall time series for 15 hours in increments of 0.250s, I need to convert it from a .txt-file to a raster.
I've tried using r.mapcalc in GRASS, however, have not been successful. I've also ...
-2
votes
1answer
75 views
Calculating the Groundwater travel time using GIS and calculting the average velocity and flow pathlength
I get the difficulty just same as shiny met, but It did not work out from the original question website yet. The question just expressed by mwill as follows:
I’m working on building a GIS based ...
2
votes
0answers
47 views
Short streams and tiny basins | QGIS-SAGA
After watching a lot of tutorials and trying all approaches I still somehow manage to get streams that are too short over my DEM, resulting in very small basins. I do it the standard way:
Get a DEM
...
0
votes
1answer
127 views
Opposite of r.carve in QGIS - r.wall or r.dam?
I wonder if there is a way to perform an operation similar to r.carve, but instead of carving in the stream based on the low elevation on the extremes of a line, it fills a barrier based on the high ...
3
votes
2answers
175 views
Forming continuous network out of discontinuous lines in ArcMap
I have river data, which consists of lines (narrow sections of streams) and polygons (wider sections of streams). I would like to have all data in line form.
First, I tried Collapse Dual Lines to ...
2
votes
1answer
88 views
How to find out which areas are affected by flooding due to heavy rain?
I'm working on a little project to visualize affected streets of flooding due to heavy rain. I already got a DEM for my study area and filled the depressions with r.fill.dir.
Since I never worked on ...
3
votes
0answers
37 views
TauDEM: How to extract the longest flow path from an outlet to the basin divide as a shapefile
Using TauDEM I've created a number of derived raster products from an initial 30m SRTM DEM with a statewide (South Carolina) extent. Using the D8 modelling methods, I've created both the D8 Flow ...
2
votes
1answer
64 views
TauDEM fails to create stream network shapefile (-net option) when running StreamNet method on Ubuntu
When I try running TauDEM's "StreamNet" method including the optional -net flag to create the stream links / channel network as a shapefile, it fails with a lot of errors like:
ERROR 10: ...
3
votes
1answer
92 views
QGIS: How do I combine/summarize information from several attributes to one specific attribute?
I have a pretty specific question and I dont know how to approach this.
I have a polygon layer for subbasins in the Danube area (HydroShed) which also contains information for water discharge.
The ...
1
vote
0answers
157 views
How to interpret the Maximum flow path length raster, from the SAGA Maximum flow path length tool
Does anyone know how to interpret the Maximum flow path length raster, after running the SAGA Maximum flow path length tool?
I have used this tool and received a raster but I'm not sure how I can get ...
2
votes
2answers
288 views
Isochrone along direction map of watershed
I am interested in producing a isochrone map given a raster speed map and a direction map (like the output of r.watershed), but I do not see how to produce it.
I have studied r.walk and r.cost wich ...
0
votes
0answers
68 views
Catchment area raster values
In order to calculate TWI, I had to generate a catchment area raster, but I don't understand what the values of pixel represent. Any clarification?
The DEM is projeted in EPSG : 2154, so the unit is ...
2
votes
1answer
86 views
How to automate flooded area calculation and make report using PyQgis?
I have 3 shapefiles with me. They are a flooded layer, District layer and Village layer. To estimate flooding village wise, I have to do intersecting the features and get the layer. Then I calculate ...
2
votes
1answer
178 views
QGIS: Burning stream network (catchment area)
I need help from stackexchange because of a DEM correction problem...
I have a DEM with a 5 meters resolution where one of the main river is cut by a large highway. In order to delete that topology ...
0
votes
0answers
404 views
Watershed delineation using hydrological Python library
We would like to delineate watershed polygon for a given pour point using hydrological Python library.
Until now, we have tried these libraries:
pyshed
Grass (r.watershed)
Whitetoolbox
We have ...
1
vote
1answer
284 views
GEE: masking for multiple pixel values
The GEE tutorial shows how to mask an image for one pixel value using .eq(pixel value).
However, I want to mask all pixels in an image with a value of 15 or less in this dataset
var riverflow = ee....
0
votes
1answer
106 views
Cascading order of basins (next downstream basin) in QGIS, R, or Whiteboxtools
I am conducting a hydrologic analysis of DEMs. Suppose that I have the following basins in an area as shown below:.
I need to get the cascading order of each of the basins. In other words, I need to ...
1
vote
0answers
106 views
Get catchment area of a lake polygon in R
I have several DEMs as geotiff files which I load into R using raster::raster. Additionally, I have lake outlines (located within the DEMs) in the form of shapefiles which I load into R using raster::...
1
vote
0answers
49 views
Why am I getting a straight flow path (stream) in obviously varying terrain -QGIS
Does anyone have suggestions on why the streams are sometimes represented as longer straight lines, even though the hillshade and contours generated from the same DTM (filled) clearly indicate that ...
4
votes
1answer
155 views
Optimizing pixel extraction from GeoTiff using Python
I am creating IDF Curves for work using python and 30-minute rainfall rate rasters. There are 24 rasters per day and about two decades worth of data. I basically input lat/lon coordinates and my ...
3
votes
1answer
187 views
Apply volumes to points on a raster DEM in QGIS
I am trying to create a flood inundation map in QGIS from known flood volumes at specific points across a raster DEM. I could potentially do this manually for each individual point using contours ...
2
votes
1answer
132 views
Identify main inlet of a lake in ArcGIS
I'm trying to figure out an automated way to identify mountainslopes from where a rockfall could hit lakes using the hydrological tools of ArcGIS 10.7. As rockfalls do not behave like runoff water, ...
1
vote
0answers
83 views
Urban runoff volume calculation
I was wondering if someone could help me out on how to calculate runoff volume within an urban area ?
I have already produced different outputs:
Filled DEM
Catchment area
Channel network
flow ...
0
votes
4answers
334 views
Seeking free software for rain catchment area?
I want to be able to calculate the catchment area that would feed rainwater into proposed swales.
I can do this easily enough, and with sufficient accuracy--not much accuracy is really needed, on a ...
-1
votes
2answers
110 views
Fill a sink with a known volume of water to obtain actual depth and extent of a pond
Using ArcMap 10.7
I have a raster with sinks in a terrain that I developed by processing a DEM dataset. Each sink has been delimited and turned into a polygon too, and its total volume was ...