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.
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Is a normal consequence of Fill SInks (Wang & Liu) to drastically alter the range of a DEM, and if not what could be happening?
I ran Fill Sinks (Wang & Liu) on a small DEM. The elevation range on the input was about 39 to 235. The range for the output was about 128 to 771.
My understanding of this tool is that it should ...
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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:\...
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GRASS r.sim.water results in "ERROR: Raster not found" in QGIS. Function in GRASS standalone works. How come?
I am trying to simulate overland flow, using GRASS 7 r.sim.water in QGIS from the processing toolbox. I have a DEM raster and calculated the dx and dy derivatives using r.slope.aspect. These are the ...
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Results from Strahler order/Stream rank (order) "cut" into squares - why?
I have DEM (30m/px) from SRTM, but when I run the SAGA Strahler order in QGIS 3.30 I get strange results - see below.
Why is the image is "cut" into squares of 1km?
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Problem with r.fill.dir on merged raster layer
I am going to use r.fill.dir on an area. The downloaded data comes as a set of tiles that puzzle together.
In order to delineate watershed across tiles I need to merge them to a complete raster.
...
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1
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Cumulative distance along a raster stream network
I am looking to calculate the cells along a stream network from starting points to a maximum distance and stopping points. I need something like r.cost in GRASS (https://grass.osgeo.org/grass75/...
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Listing stream-segment IDs for fluvial junctions with Field Calculator
Issue #3 as concerns my comeback geofictional project.
At this writing, I've tried my best (for many hours now) to come up with a Field Calculator formula that gives a list of comma-separated stream-...
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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 ...
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To and from nodes in stream network using Whitebox Tools (in R)
I am experimenting with the WhiteboxTools via the WBT library in R. This is to design a scriptable and open-source workflow to extract stream networks from a digital elevation model (DEM).
From ...
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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 ...
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QGIS Strahler Order Too Many Stream Channels
I have this DEM file and I'm trying to extract possible rivers/streams from it.
However , when I run Strahler Order as tutorials on youtube indicate, the output shows too much lines that aren't really ...
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Drainage area at a point of my choice
I want to get drainage areas at specific points (the points are places I want to put culverts for a railwork construction).
The thing is that when I run either upslope area or PCraster tools, the ...
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Why input layers do not have the same grid extent in the processing, hydrological analysis?
I'm trying to generate the hydrological analysis using processing and I have already done some terrain processing using the DEM.
In this moment, I'm working in he channel network but, when I assign ...
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Find minimum downstream flow distance from each polygon to any polygon in other feature class
The Problem:
I have two polygons feature classes, let's call them "SourceAreas" and "DangerAreas". For each SourceArea, I need to know if water could flow to any DangerArea and if so, what is the ...
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QGIS Catchment Creation from existing line shapefile (streams)
I understand the general process of creating a catchment.
Get DEM data Fill sinks
Build stream network
Create a line shapefile of the stream network
Choose outlet location and obtain coordinates
...
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Finding glider reachable area / catchment area with custom slope?
I'd like to produce maps for gliders in mountains.
I'm looking to display the reachable area by a glider taking off from a given point (obviously with the corresponding DEM).
For a first approach I'...
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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 ...
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QGIS SAGA Isochrone crashes
I am trying to make isochrones with SAGA GIS.
I am now having a problem that:
The Isochrone variable speed crashes or give odd outputs.
I have a DEM with 3.6km2, but the output is about 3 pixels,
even ...
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How to find a specific distance upstream from a point
I am trying to find a simple way to map sections of a river which are covered by a Mink trap.
So I have a river layer and a points layer for where the traps are placed.
I want to select all rivers (...
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Determining maximum capacity of river using HEC-RAS
Is there a practical way to determine the maximum hydraulic capacity of a river in HEC-RAS?
I would like to know for each cross section of my 1D model what the maximum flow rate will be before ...
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Automatically generating pour points along stream network?
The following screenshot shows the results of a water flow analysis where I identified stream order via the Strahler method in ArcGIS. Now I need to generate watersheds for 2nd order streams and ...
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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 ...
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Transfering attribute from line layer to polygon layer by their overlay in QGIS
I have a polygon layer that represents sub-catchments and a line layer that represents a stream network. There is exactly one feature in the line layer for each polygon. I have used v.rast.stats to ...
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QGIS: Further subdivide sub-catchments based on DEM
I have a DEM and a vector layer with existing hydrological sub-catchments. Is there a way in QGIS to further subdivide the sub-catchments based on the DEM?
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Finding average depth of filled sink using ArcGIS Pro
How to find out the depth of a filled cells (filled using "Fill" tool for a DEM)?
I have a DEM (50m resolution) for which I used "Fill" tool of the hydrology tool of ArcGIS Pro to ...
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Perform a Mann-Kendall test on grd dataset downloaded from imd portal
I have a grd file downloaded from imd portal, now I want to perform a mann kendall test on this grd dataset. But I am not getting how to read grd file in Python and how to perform Mann-Kendall test, ...
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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 ...
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QGIS: Flow Accumulation Tool not progressing past 100%
I'm trying to do run the flow accumulation tool on a map where I am trying to extract drainage from a DEM however it has been stuck at 100% for several hours. I have put details of the files I am ...
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Strahler ordering of existing vector stream network data with a DEM (SRTM)
I have a vector stream network (CanVec) and an SRTM DEM. How can I elucidate the Strahler order and attach that value to the vector stream network? For some reason the CanVec data doesn't have ...
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ERROR 010658: Failure in distributed raster analytics operation. Error when using hydrology tool 'Fill'
I'm currently doing a watershed delineation and river morphology computation using ArcGIS Pro. I have the DEM of the area and started with the hydrology tool "Fill" but it keeps having an ...
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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 ...
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Creating point at downstream end of polygon using ArcGIS Pro
I'm trying to automate the process of adding a point to the downstream end of each polygon in a layer in ArcGIS Pro (Running V3.2.0 on Windows 11). I have a layer with the stream network along with a ...
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Creating Streams from endpoints and NHD Stream Layer using ArcGIS Pro with Spatial Analyst
I have a dataset for instream flow water rights that delineates the length of stream based on upstream and downstream endpoints and the miles of stream. I'm trying to create a GIS layer for this ...
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FlowAccumulation working when run as geoprocessing tool but not in ArcPy
I have a problem with this code:
#actual problem code
flow_dir_rast = flow_dir
in_weight_raster = mine_flac_weight
data_type = "FLOAT"
flow_direction_type = "d*"
# run the flow ...
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Tracing a specified distance along a network using ArcGIS Pro
Using ArcGIS Pro 3.1.
I have some starting points snapped to a network of river lines (purple in image). I would like to trace exactly 500m away from these points in either direction as below (red), ...
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How can I use Whitebox hydrology tools with areas of internal drainage (ie. true sinks)?
I'm trying to use some Whitebox hydrology tools on a raster where I want to set inland points as areas of internal drainage and I don't understand how the fill tools treat NoData points when filling ...
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Selecting or highlighting upstream elements
I would like to use the information from the Swedish SMHI related with their hydrological model elements (catchment areas) that have a Containment hierarchy structure, each element has the information ...
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Terrain creation error using a GeoTIFF file with HEC-RAS 6.2 - "object reference not set to instance of object"
I am attempting to import a TIFF file created in QGIS, into HEC-RAS. I have a projection file as the SRS definition for HEC-RAS, which is derived from a shapefile that lines up with the spatial extent ...
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Using ArcGIS Pro to calculate required height of debris dam structure in stream when expected volume to retain is known
I have the locations of potential debris dam structures to be placed in a stream and know the contributing watershed area and the estimated debris volume (in m3) that would flow down that watershed ...
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Calculating flow path length in R
I am currently trying to calculate the flow path length in a DEM towards a streamnetwork. My desired outcome would be a raster with values of how long the flowpath to the nearest streamcell would be ...
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Delineating large scale watershed?
I would like to do some watershed delineation at national/regional level (using SRTM-90 data).
I have experimented with r.watershed (GRASS 6.4.3) but it fell over when I tried to do big stuff.
I ...
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Generate a very accurate mask showing where rivers and streams are using a DEM in QGIS
I would like to create a mask layer to show what the specific widths of a river or stream would be with certain variables. I'm using a high quality 1mx1m resolution DEM. I am able to do some things ...
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Estimating flow direction using `terra::terrain()` without NA values at the border
Performing some rather simple watershed delination analysis I noticed {terra} offers a function to estimate at least the flow direction based on elevation input via terrain(x, v = "flowdir")....
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How to divide watersheds by iscochrones/travel times in QGIS?
I need to divide my watershed by isochrones of equal travel time to the output, dividing my watershed to inter-isochronal areas in order to use the time-area method to calculate runoff time series, in ...
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Validating that the smallest channel extracted using ArcMap (Hydrology toolbox) from DEM is the first-order stream
In ArcMap, the 'Hydrology' tool under the toolbox 'Spatial Analyst' can be used to extract the stream network, as described in detail here: extract streams from DEM. One step consists of using a ...
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LAS to DEM conversion [closed]
I regularly come across LiDAR (.LAS) files with elevation data. When I do, I always struggle to find a way of converting them to a DEM for hydrological analysis. I have developed several workflows, ...
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Choosing parameters for SAGA Wetness Index?
I've been working with SAGA GIS to calculate the Topographic Wetness Index of an alpine catchment. I am using the tool Terrain analysis > Hydrology > SAGA Wetness Index because, compared to ...
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Calculating flowpaths downstream of a point
I am assessing the flood risk posed by pipeline failure. I need to calculate the likely flow-paths for flood water downstream of critical locations along the pipeline using GIS.
I'm familiar with ...
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Hydrology, operational rainfall-runoff models
I am trying to collect information about operational rainfall-runoff models used around the world. I hope to build database with country outline with attached information what organization is covering ...
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How to speed up batch watershed delineation?
I have a large number of pour points - approximately 250,000 for which I want to delineate the upstream watershed area using ArcHydro's "Batch Watershed Delineation". Given that it takes roughly 4-5 ...
