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.
77
questions with no upvoted or accepted answers
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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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1
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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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246
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SAGA hydrological analysis in QGIS 2.8 on Mac
I am running QGIS 2.8 on a Mac machine and I want to calculate the catchment area using SAGA - Catchment Area. It starts running but after a while when QGIS wants to open the generated files there is ...
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3
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LiDAR derived streams - map scale
Historically, streams were defined by the map scale. For example, for a map with a scale of 1:24,000 would mean that the streams identified on that map would be 1:24,000 streams.
With streams that are ...
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3
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359
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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 ...
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3
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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 ...
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201
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Extract representative slope profiles from hillslope polygons
With the help of the Whitebox Geospatial Analysis Tools I was able to easily extract hill slopes from a river network in combination with a flow direction map.
Now I would like to extract ...
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3
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157
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Which geostatistical tools to use to determine surface changes over 40 years?
I have a data from the Weather station with SWEmax (snow water equivalent) collected over 40 years. I need to interpolate the data over my river's watershed and then, somehow, determine the ...
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2
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64
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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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2
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Calculating upstream (contributing) area for >10,000 points using Python
I would like to create polygons of the contributing area for > 10,000 points.
I have all information that I need for this, including a 30m DEM, a river network (LineString geodataframe file) and ...
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2
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86
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Bringing river bed to the same height as surrounding ground in QGIS
I have a DEM containing the current flow networks in an area. I also have a shapefile showing the same flow network. I would like to derive a new river network to see how water would flow if the ...
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134
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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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2
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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 ...
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218
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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 ...
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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
...
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2
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701
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Vector map (rivers) to Raster. [ **ERROR 1: Wrong value for -outsize parameter.**]
I want to transform this vector map:
To something like this
I only tried to convert the vector map through Raster> Conversion> Rasterize
But I get this Error:
QGIS version: 3.6.3-Noosa
QGIS code ...
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2
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0
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383
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Extract longest flow path in ArcGIS pro
I did calculate Hydrology with Spatial Analysis tools==> Hydrology and now, I have streams and Watershed. In each watershed, I need to extract the longest Flow as a polyline for calculate slope. What ...
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2
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97
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Channel network from high resolution DEM for flat areas
I'm working on channel network extraction from a LiDAR DEM (square grid max resolution 0,25 cm), and my area of study is vary flat with some part below the sea level.
I applied the classical valley ...
2
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212
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Choosing diffusion coefficient and other parameters for r.sim.water in GRASS7?
I'm trying to run r.sim.water in GRASS7 to simulate overland flow during a heavy rain event.
My DEM has a resolution of 1m. I prepared it by adding values for buildings and included ditches and ...
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2
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158
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Connectivity of Streams
I have a line vector layer containing streams (see image below). What is the easiest approach to determine the connectivity of each stream segment (eg. sum of upstream nodes)?
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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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1
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1
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How to add a column in one shapefile that is the sum of values in another shapefile?
I am trying to calculate a weighted average CN value for 500 drainage area catchments (S1-S500).
I have one file named "DA" which has S1-S500.
Name Total_Area
S1 1.5
S2 0.8
........
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1
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264
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Python library for hydrology calculations for multiple points
I have a DEM (TIFF) with multiple points, which mark wells (right term?) of an underground pipe network:
I was wondering if there is a Python library which uses the elevation of the DEM to generate a ...
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50
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HEC-GeoHMS Outlet Point Connectivity
The "Check Data" option in HMS tab of HEC-GeoHMS is showing a problem in the VIP relevance points which is as follows:
Checking project points [VIP points]... Checking VIP Point: Outlet1
...
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1
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77
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Delineate watershed
I have a problem with QSWAT. It does not take the delimitation of my catchment, I did all the solutions that I know.
I downloaded a new SRTM and the same projection with all the parameters. I ...
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1
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168
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QGIS: Creating a point at a set distance up/downstream from another point (dams or obstructions) on a line object (river)
I have a data set where I have shapefiles for the watercourses in a drainage basin (line/linestring) and locations of dams and other obstructions along them (points). I would like to create a new ...
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1
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531
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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 ...
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50
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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 ...
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68
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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 ...
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1
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371
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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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1
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420
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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 ...
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191
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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::...
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91
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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 ...
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294
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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 ...
user157535
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92
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Calculating the volume of multiple lakes with ArcGIS (3D Analyst)
I have the DEM of a glacier bed and want to calculate the volume of bed depressions that could form lakes. Data is available here: https://drive.google.com/open?id=1ERFdsqDGLH1a_FbxwawE_gPm0Au0Q9vT
I'...
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436
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Calculating drainage density
How can I calculate drainage density in QGIS if I have length for stream and grid line 1 km2? I need to calculate density per km2.
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864
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SAGA: could not initialize data objects (QGIS 3.6, Mac 10.14)
I was trying to generate a catchment area from a DEM and got the error message:
The following layers were not correctly generated.<ul><li>/var/folders/ft/rbsnpzy96r76t8rkj5fdtzc40000gn/T/...
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Calculating SCS curve numbers using DSM instead of DTM
Are the curve numbers (calculated by SCS Curve number method) through DSM (Digital Surface Model) valid? Most of the SCS curve number studies focus on calculating curve numbers through a DTM (Digital ...
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Split single polyline network at a point feature to make unique fields with unique distances
I am working with a large river network polyline shapefile. I am trying to calculate a dendritic connectivity index using a point shapefile representing locations.
The river network shapefile has a ...
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Displaying flow direction using arrow in ArcGIS Desktop?
I created a flow direction raster out of a DEM using ArcGIS Spatial Analyst Tools/ Hydrology, so the directions are coded in raster values as displayed below.
[http://desktop.arcgis.com/de/arcmap/10....
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Automatically locating endpoints (river sources) in a stream network
I have a stream network in ArcGIS 10.2.2 and I would like to know if it is possible to automatically add endpoints based on the stream network.
The network is pretty big and doing this manually ...
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1k
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Qswat in newer version of QGIS
How can I setup QSWAT in newer versions of QGIS ? The link here says QSWAT requires QGIS 2.6. I tried installing QSWAT in new versions and it couldnot be done.
Is there a way to install QSWAT in new ...
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221
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Adding curb/gutter and subsurface storm drain networks to watershed analysis in QGIS
I need to do a neighborhood scale drainage analysis. The analysis needs to accurately show the drainage area to each storm drain inlet. Using GRASS on QGIS 2.12.1 on OS X, I have been able to ...
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calculate flow accumulation in a river with two outlet points
I'm trying to calculate flow accumulation layer (with arcGIS) in a basin with 2 outlet points. I have used "dem reconditioning" tool to modify my dem according to a vector layer, which contains my ...
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Deriving Stream-Velocity out of a DEM
I'm using Arc GIS Toolbox Hydrology...everything works fine. Moreover, it is possible to derive the potential stream velocity just out of the DEM? Informations about rainfall, infiltration, hydraulic ...
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158
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Getting distance from nearest stream and elevation to nearest stream?
I need to know if there are simple commands for this 2 points:
the distance from the nearest stream, D [m], defined as the length of the path that hydrologically connects the location under exam to ...
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574
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Why does the flow direction tool in ArcGIS desktop give wrong output (unique values from 1-255)?
I ran the flow direction in ArcGIS, and received unique values ranging from 1-255. I know that these values are wrong, and should be along the lines of 1, 2, 4, 8, 16, etc multiples. The DEM is ...
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492
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Measuring river width every mile in Google Earth?
Given an area, can Google Earth tabulate the width of a particular river?
This problem I think requires using an API to programmatically:
define an area of interest
identify a terrain feature like ...
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1
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47
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How to join hydrological data from a big area with a small area with better pixel resolution?
I use TAUDEM to make hydrologic analysis.
I have a hidro 1K dem file from South America (big area) pixel resolution=1000x1000 meters.
I have a specific dem file located in Brazil (small area) pixel ...
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1k
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How can we extract the stream order branch?
Actually I am new to GIS, so I don't know much about technical terminology.
I have extracted a river network but now have a problem in distinguishing the branch order of stream (from order 1 to 2, 2 ...
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