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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How to resolve the problem of multiple parallel streams and unmatched river flow in Stream Network?

I am working on sub-watersheds delineation of an area. The extracted streams do not match with the real world scenario. I have two issues; there are multiple streams lines which do not match with ...
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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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Tool generating hill slope forms (divergent, convergent, uniform) in QGIS

Does anyone know a tool or procedure for generating a raster file of slope forms (divergent = upper slope wider than lower slope, convergent = upper slope narrower than lower slope and uniform = upper ...
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3 votes
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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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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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Delineating multiple nested catchments in R whitebox; prevent primary catchment from being cut by subcatchment

I am using whitebox tools in R to delineate catchments. I have 150 lakes in a rather small area so many of the lakes are within the same catchment. I use wbt_watershed(d8_pntr = ptr, ...
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Hydrological catchment area for a road segment (QGIS)

I try to calculate the hydrological catchment areas for road segments in a mountainous region in QGIS. As far as I see, I can only calculate watersheds in general or for particular points. Is there a ...
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Basin code in Google Earth Engine

How to find 6digit in HYBAS_ID of "WWF HydroSHEDS Basins Level 7" database. Technical Documentation says that: Next 6 digits represent a unique identifier within the HydroSHEDS network; ...
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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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5 votes
1 answer
258 views

Calculating width of unusually shaped polygon in QGIS

I have a large unusually shaped polygon of surface water within 15km radius of a site. I would like to calculate the widths of all the polygons. I would be open to calculating it at regular intervals, ...
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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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Calculating distance along line to central point QGIS

I have a layer of various water courses. I have a central location which is a reintroduction site for an animal. I want to calculate the minimum distances along the lines of the water course to the ...
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QGIS Watershed Delineation - generated channels and drainage basins are incorrect

I am trying to delineate some watersheds using the SAGA GIS Tools in QGIS. The DEM I am using is the SRTM DEM. When I try to generate the channels and drainage basins using the SAGA>Terrain ...
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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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Watershed analysis in ArcMap, interpreting results to find contaminant

I am doing an analysis to find a possible contaminant in a river. I have trouble interpreting the results of my watersheds. I have filled sinks, got a flow direction and flow accumulation and I have ...
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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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2 votes
1 answer
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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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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 ...
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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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"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 ...
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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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1 answer
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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, ...
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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 ...
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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 ...
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1 answer
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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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1 vote
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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 vote
1 answer
86 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 ...
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1 answer
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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 ...
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1 vote
1 answer
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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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2 votes
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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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1 vote
1 answer
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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 ...
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2 votes
1 answer
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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 ...
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5 votes
3 answers
341 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 ...
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1 vote
1 answer
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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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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 ...
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3 votes
0 answers
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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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2 votes
0 answers
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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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2 votes
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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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1 vote
1 answer
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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 ...
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-2 votes
1 answer
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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 ...
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2 votes
0 answers
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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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0 votes
1 answer
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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 ...
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3 votes
2 answers
238 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 ...
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2 votes
1 answer
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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 ...
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3 votes
0 answers
59 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 ...
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2 votes
1 answer
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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: ...
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3 votes
1 answer
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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 ...
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1 vote
0 answers
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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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2 votes
2 answers
419 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 ...
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0 votes
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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 ...
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