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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26 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 ...
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31 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:\...
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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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How to export selected pour points from a watershed raster into a point vector file in ArcGIS Desktop 10.1 [closed]

After having produced a watershed and executed a snap pour point on its output how can I export selected pour points values into a point vector file.
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1answer
59 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 ...
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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/...
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1answer
36 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 ...
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2answers
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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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1answer
61 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 ...
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28 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 ...
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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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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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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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1answer
80 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 ...
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1answer
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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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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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1answer
71 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 ...
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2answers
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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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1answer
64 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 ...
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How do I determine the correct ratio to peak value for the Recession baseflow in HEC-HMS?

I am wondering if there is a way to estimate the ratio to peak value without calibration? What would be the most suitable value if I don't have a measured hydrograph to compare? Thanks for any ...
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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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1answer
38 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: ...
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30 views

How to aggregate properly 8-days MODIS ET to a monthly ET?

I am looking for a robust method to aggregate the 8-day MOD16A2 (or MOD16A2GF) ET_500m values to monthly ET. Since ET_500m and PET_500m, are the summation of 8-day total water loss (0.1 kg/m2/8day). I ...
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1answer
68 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 ...
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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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2answers
214 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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41 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 ...
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19 views

Water direction and intensity of superficial flow

I'm working on maps that the goal is: to display the direction and intensity of surface water flow. I have the DEM for the watershed and generated the direction of flow, but I don't know how to ...
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1answer
68 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 ...
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1answer
105 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 ...
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238 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 ...
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1answer
135 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....
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64 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 ...
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74 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::...
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Add buildings contours to DGM for hydraulic analysis [duplicate]

I use Hydrology Terrain Analysis Tools in QGIS/ArcGis. Now I try to add some building contours to my DEM. I got building Data (Polygons) and a Raster DEM. Finally I want the buildings added to my DEM, ...
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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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1answer
106 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 ...
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1answer
134 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 ...
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1answer
104 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, ...
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77 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 ...
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4answers
207 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 ...
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2answers
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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 ...
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1answer
85 views

Creating flood inundation map from watermark QGIS

I have a high water elevation for a location and I want to subtract this elevation by the DEM raster to achieve a water depth raster, and I am not sure how to go about this. I am assuming a constant ...
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1answer
65 views

Population in upstream area (looping over FeatureCollection)

I want to calculate the sum of the population living in the upstream area of stations using the hydro package by gena. I think I will have to loop over the stations (using the identifier "GEMS_Stati")....
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1answer
80 views

Changing lakebed symbology to relative depth in ArcGIS 10.5 (TIN or raster file)

I have several TIN files representing empty lakebeds at altitudes ranging from 5000m to 3000m. I have calculated the TINs using ArcGIS hydrology tools and an ASTER v3 DEM projected to ...
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1answer
87 views

Calculating volume of several TINs in ArcGIS Desktop

I am trying to calculate the volume of several TINs using the 3D Analyst of ArcGIS 10.5. My data can be found here: https://drive.google.com/open?id=1ERFdsqDGLH1a_FbxwawE_gPm0Au0Q9vT For a start, I ...
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0answers
40 views

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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0answers
42 views

Using ArcGIS to quantify sink volume in glacier bed (“sink” and “fill” tools)

I am trying to identify sinks/overdeepenings in glacier beds and quantify their volume. If you take a look at my data (https://drive.google.com/drive/folders/1ERFdsqDGLH1a_FbxwawE_gPm0Au0Q9vT?usp=...
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0answers
155 views

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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54 views

Create catchments/subbasins for specific nodes

I have an XPSWMM model of a neighborhood storm drainage system. Nearly all of the drainage is above ground through a network of ditches and culverts. I still need to create catchments for the ...

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