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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28 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 ...
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1answer
29 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
66 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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1answer
54 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
16 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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14 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
56 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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42 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 ...
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2answers
163 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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29 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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17 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
57 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
74 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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82 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
63 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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1answer
45 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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47 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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19 views

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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40 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 ...
2
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1answer
69 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
110 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
90 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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67 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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23 views

Monthly albedo data for VIC

I am trying to download Albedo data for my research area. On NASA's Earthdata website I used the MODIS product MCD43A3,. First reason why I haven't downloaded the data is because my research period is ...
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4answers
146 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
69 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 ...
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1answer
62 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
56 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
73 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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183 views

Get catchment delineation with multiple outlets in QGIS 3.4 or 3.8

I'm starting with a DEM, then I generate a drainage direction layer (ldd). Then I'm trying to get all the watershed basins for multiple outlet points in a QGIS plugin I'm developing. I can get them ...
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1answer
64 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
33 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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39 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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96 views

QGIS Grass 7 r.fill.dir

The following layers were not correctly generated.C:/Users/JIM/AppData/Local/Temp/processing_e2688a45d8934d16a2269a7ef6af8cbd/7eefcc8d13144f598fa7ab5bb5d657b8/output.tifYou can check the 'Log Messages ...
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0answers
103 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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46 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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0answers
144 views

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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1answer
82 views

Quicker function than dissolve and difference

I'm on QGIS (v. 3.6) trying to create a map of Florida's hydrography using the NHD "Water Areas" shapefile. Methodology is to fix any invalid geometries in the NHD data, dissolve the layer, and then ...
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102 views

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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0answers
301 views

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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37 views

Flow Distance Not Calculating for Entire Raster

I am trying to calculate the height above the nearest stream for an area. The problem is, it only does so for a portion ( the colored area below) of my area of interest. In the pic below, the black ...
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1answer
42 views

Creating symbols between connecting lines to represent line boundaries

I am trying to figure out a way to create markers as seen from the attached image where an angled line (in dark red) is created between the lines to represent a connecting stream. With the data I am ...
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0answers
14 views

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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1answer
105 views

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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0answers
106 views

Howerive vector stream network from a DEM using D-Infinity Flow Direction algorithm?

I have been working with a 1m LiDAR derived DEM to create a vector stream network. Using the D8 flow direction, D8 flow accumulation, and a specified threshold, I was able to create a vector stream ...
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1answer
58 views

Using GageWatershed Function in TauDEM?

I have a D8 flow direction raster made from with TauDEM's D8FlowDir method and a point vector with an attribute 'id' for each. For some reason when I use these two as input in the GageWatershed ...
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1answer
72 views

How can I find the elevation a set distance upstream and downstream from a layer of crossing locations

I have a channel network which I've intersected with a proposed road network to produce crossing locations. I need to find the channel slope averaged over a 20m stream length. I also have a raster ...
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1answer
42 views

Watershed layers that drain to ocean?

I have been searching for a watershed layer for California or for the entire US that encompasses all upstream area from ocean outlets (e.g. the entire catchment draining into each ocean output). I ...

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