Questions tagged [watershed]
Use this tag when asking a question about a watershed related to GIS environment.
0
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1answer
19 views
Calculating distance between points following flow direction on ArcMap?
I delineated flow directions in a watershed on ArcMap (10m DEM). Then I want to calculate distance between two points 'following' the flow direction in each raster cell, not a straight line distance.
...
1
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0answers
24 views
What does the values of Watershed Accumulation, Basin, In QGIS indicates?
While performing watershed module in QGIS each output gives some value range while changing color palette. what does it actually means in accumulation , basin, stream flow. What does the value ...
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0answers
30 views
Watershed delineation by using QGIS with ifsar dtm 5m resolution of grid
I had some problems during running the channel and drainage basin with an IFSAR DTM, 5m resolution. I followed these steps, according to the guidance from website of QGIS:
I reprojected the DTM to ...
0
votes
1answer
15 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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0answers
29 views
Quantitatively evaluating quality of watershed delineation stream line results?
How can we quantitatively describe the quality of watershed delineation?
What metrics can I use to compare the stream line differences between a few delineations using different DEMs with different ...
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0answers
25 views
Getting gridded population to resolution of land cover?
I have a population data at census tracts level and an impervious land cover. Impervious land cover is of 30 m resolution and census tracts data stored as a vector. Is there any way that I can ...
2
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0answers
120 views
Watersheds and Catchment delineation in Earth Engine only with included datasets
Is there a possibility to derive Watershed boundaries or catchment areas by using one or more of the integrated data sets in google earth engine?
The available data sets are:
WWF HydroSHEDS ...
2
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0answers
14 views
Why difference in delineation of watershed by two online watershed modeling tools?
I am using two online watershed delineation tools- eRAMs and Model My Watershed (MMW)- to auto delineate watersheds using water quality monitoring sondes as my outlet points. I have three pieces of ...
3
votes
1answer
57 views
Watershed a catalog RasterStack in place of RasterLayer in lidR?
I want to use watershed with lidR package on a catalog. I paste this command:
rep <- "/home/lasfiles"
new_ctg <- catalog(rep)
lidR:::catalog_laxindex(new_ctg)
opt_output_files(new_ctg) <- ...
2
votes
1answer
56 views
Tolerance setting in watershed segmentation(EBimage/lidR) in R
Can anyone here explain to me what the "tol" parameter in the watershed algorithm implemented in the BioConductor package EBImage (and lidR) does?
I find the explanation in the EBImage help difficult ...
1
vote
0answers
39 views
Using minus in water drainage model
I'm doing a lab and I'm trying to understand exactly why I'm using the tool "minus".
I have a raster which I'm calling "heights". I also have two rasters with water surfaces and watercourse. I have ...
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0answers
43 views
Using tool “minus” in height model?
I'm doing a lab and I'm trying to understand exactly why I'm using the tool "minus".
I have a raster which I'm calling "heights". I also have two rasters with water surfaces and watercourse. I have ...
0
votes
1answer
195 views
DEM File “not found” Error when running r.watershed with Processing Toolbox in QGIS 3.4.2 with GRASS
I have downloaded a DEM from the NASA server with "SRTM Downloader".
I want to find the watershed area, so I run the "r.watershed" function form the Processing Toolbox.
However, I got a multi- "...
1
vote
0answers
36 views
Determining if Runoff Sinks drain to stream or drain to road?
I've tried using the linked method to determine area that drains to stream vs drains to road. For some reason when I run the watershed tool on the the raster representing stream and road features, I ...
0
votes
1answer
36 views
how can interior basins be modified in the r.watershed GRASS function?
This is a follow up question to
How does "Minimum Size of Exterior Watershed Basin" work in r.watershed command in qgis 2.18.12?
I understood that the threshold parameter is used to ...
0
votes
1answer
135 views
Creating catchments/basins around stream feature class using ArcGIS Desktop?
I have a reasonably accurate steam network for a watershed. This network includes the main channel, major forks, and tributaries. Each channel, fork, and tributary are individual records with single ...
0
votes
1answer
315 views
Watersheds in SAGA Fill Sinks Wang & Liu tool
I'm delineating some coastal subbasins using open source software. I have asked a similar question before (Delineating coastal subbasins using SAGA GIS or GRASS in QGIS?). I found that using SAGA Fill ...
1
vote
1answer
93 views
Large Scale Watershed Delineation
Using QGIS,I attempted Africa's watershed delineation taking the following steps:
Downloaded DEM from earthexplorer USGS (GTOPO30)
Created a mosaic of the downloaded DEM
Reprojected the mosaic ...
0
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0answers
37 views
How to calculate summed pixel area of multiple classes over a grid? Google Earth Engine
I'm trying to calculate the percent area of each transition class type (using the surface water occurrence dataset from the GEE tutorials) within a .25 by .25 degree grid box in SW Alaska.
Here's a ...
1
vote
1answer
480 views
DEM reconditioning?
I'm using ArcGIS Desktop 10.5 Arc Hydro Toolbox & encountered a problem while trying to delineate watersheds respectively drainage lines.
The red lines indicate my obtained drainage lines, which ...
1
vote
1answer
433 views
Google Earth Engine, how to distinguish between rivers/streams and ponds/lakes in a water mask
I am trying to pull out every lake and pond in a region of SW Alaska. I have successfully identified all water features using the following code:
// study area
var rect = ee.Geometry.Rectangle([-168, ...
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0answers
52 views
Getting higher stream number for lower order stream in ArcGIS Desktop?
The fourth order stream is showing greater stream number then third order stream?
0
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1answer
333 views
How to create “AGREE Stream” for DEM Reconditioning in Arc Hydro tool?
I want to deliniate streams and watershed using SRTM DEM. for this I am using Arc Hydro tool. While performing DEM Reconditioning for DEM manipulation it asks AGREE Stream as a input.
How to create ...
1
vote
0answers
53 views
How to create an inlet drainage basin layer
Using a point layer of 8,375 inlets and a DEM, how do I create an inlet drainage basin layer with contiguous basins, each delineating water drainage for and into each inlet? I used an integer DEM, ...
2
votes
2answers
159 views
How to create “roof line” for a general polygon area?
I have a polygon with an arbitrary shape ( assume that it is well-formed with no self intersection, no duplicated points etc), and I need to subdivide the polygon into sub-polygons like how one would ...
4
votes
2answers
447 views
Is D8 flow accumulation algorithm still suitable for watershed computation if terrain contains lots of flat area?
My question is inspired ( and similar) with my previous question. But this question is more concerned about the suitability of D8 ( or in general non-dispersive) flow accumulation algorithm for ...
0
votes
1answer
21 views
Why a range in area for catchments even if stream definition is set at a single size?
Using ArcHydro, I set stream definition at 5000, 20x20 cells (approx. 50 acres). I placed points at origins of each subsequent stream with batch point generation tool. Then used batch watershed ...
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0answers
34 views
ArcHydro: Subwatershed Does Not Contain Next Down ID
I am delineating watersheds for a hydrological model. I am using the "subwatershed" feature as this is what I want - the catchment area from the next upstream "batch point" to the current "batch Point"...
5
votes
2answers
133 views
Does the common flow accumulation techniques still work over flat area?
My terrain is a highly developed area--which means that
It involves lots of flat area ( gradient=0) because they have been properly paved.
And it involves sudden drop, such as retaining wall, or ...
2
votes
1answer
240 views
Watershed Delineation Loop - r.water.outlet resulting in NAN area while snapped
I am attempting to create multiple watershed delineations for stations within a CSV file. I have files for flow direction (raster with a cell size of 30m), flow accumulation(raster with a cell size of ...
1
vote
0answers
166 views
Creating sub-watershed within a basin
I am a beginner to QGIS. My problem is I tried to create sub-catchment within a basin by using provided point datasets (river gauge location). In total, I have 12 measuring points (i.e 12 pairs of x ...
2
votes
1answer
176 views
Calculating floodplain for river section using DEM only in ArcGIS Desktop?
I'm looking to create areas where water might go when a river floods its banks. I have a pretty good resolution DEM (5ft^2 for each "square"). I'm not looking for anything super accurate or precise ...
2
votes
1answer
49 views
Watershed issue
I am attempting to create a catchment of Danube.
So far I have used the r.fill.dir to create a depressionless map and flow directions. Thus, I am now looking to use r.watershed to create stream ...
0
votes
0answers
86 views
Improve Catchment polygon processing result accuracy?
I use the ArcHydro Toolbox and ArcGIS 10.4
I ran through the regular steps of Filling Sinks of a DEM, Flow Direction, Flow Accumulation, Stream Definition, Stream segmentation, catchment grid ...
1
vote
3answers
514 views
Doing watershed delineation properly using ArcGIS Desktop?
I am using ArcGIS Desktop 10.2.
I have the contours and the stream in AutoCAD Civil, after converting to a shapefile, I exported them in GIS,
after I created the TIN from the contours below:
...
1
vote
1answer
52 views
Extracting the z-values of a stream in a watershed if I have the values of the contours
I have the z-values of the contours (physical contours) of a watershed in AutoCAD civil, but I may use them in ArcGIS 10.2 and I have already created a DEM. I need to extract the z-values for the ...
2
votes
1answer
49 views
Attributing stream segments based upon road intersections and stream confluences
I am currently working on attributing nodes along some stream polylines. The attribution is supposed to include:
1)length of the stream from it's reference point
2) the location of the node in ...
2
votes
1answer
368 views
r.water.outlet is returning blank raster in QGIS
I am Getting error "Ignoring point outside computation region: 77.0072,12.2529" while deliniating watershed using r.water.outlet in QGIS. What am i doing wrong?
1
vote
0answers
115 views
Sub-watershed boundary is partial overlap the admistrative boundary
I am using ArcMap 10.3 on a Windows x64 system.
I would like to extract the sub-watershed for a particular area. The data I used was ASTER 30m DEM and a shapefile of my study site. The first step was ...
2
votes
1answer
56 views
Spatial analysis on raster in order to get watersheds of approximate 2 ha size
I'm trying to analyse a raster in order to get watersheds at approximate 2 ha size, using flow direction/accumulation.
I've been using the steps outlined below, with initial conditions for cells ...
2
votes
0answers
41 views
Converting data collected at political units (eg. census tract) to new ecologically-defined units (eg. watershed)? [closed]
I have socioeconomic status (SES) data of every health authority (HA) in the province. I overlay a watershed boundary polygon on top of multiple HAs and would like to know: What is the SES of the ...
3
votes
1answer
263 views
calculate 3D surface area base on slope in GIS [closed]
How can I calculate 3D surface area base on slope in GIS for each morphological units in watershed?
Are there any different methods?
4
votes
2answers
7k views
How to delineate watersheds in QGIS?
I am using qgis 2.14.17 with ubuntu16. Having as input data a DEM of the region and a river network.
In the manual of qgis they suggest to use a toll of qgis: Catchment area (Parallel); I dont have ...
1
vote
0answers
64 views
Extracting watersheds at (arbitrary) pour points of waterways inconsistent with DEM
I am using ArcGIS 10.4.1.
I am trying to extract watersheds for a number of random locations along a river network. These locations represent points where certain physio-chemical qualities of the ...
1
vote
1answer
410 views
Calculating average slope of a watershed upstream of many points in ArcGIS (upstream basin slope)
I am trying to replicate a procedure that the USGS Streamstats performs on points delineated along a stream network. They call it the "upstream basin slope" Basically, for a given point that I have ...
1
vote
0answers
102 views
Finding points of sudden large changes in stream gradient QGIS
In QGIS I am trying to divide a streams shapefile at points at where there are sudden large increases or decreases in gradient.
For example at the red circle the gradient of the stream increases from ...
1
vote
0answers
57 views
Polygons merge/union using two colums values
I'm using HydroSHEDS watersheds shapefiles for a proyect. Watershed are delinated applying the rules of Pfafstetter codification.
I need to merge/union the different polygons in a same shapefile. I ...
1
vote
0answers
105 views
What causes the striations in this slope map?
I have created this slope map using a 10m DEM from alabamaview.org and I just noticed it has small striations (zoom to see):
What could cause this, and is it a big deal, or am I over-analyzing the ...
1
vote
0answers
179 views
Understanding Add Surface Info Tool (Average Slope) vs Slope Tool?
What is the difference between the values calculated using the slope tool vs the slope option in the add surface information tool?
I am making a map that displays watershed slope (using the slope ...
2
votes
1answer
360 views
Extracting flat areas and saving them as lakes using QGIS?
I would like to extract lakes and sea from a DEM (SRTM) and save them as a separate layer.
Is this possible?
I have tried to extract flat areas with the Raster Calculator, but that did not work.
