A watershed is the area of land where all of the water that is under it or drains off of it goes into the same place.

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How to separate shared watersheds?

I put a pourpoint at the end of a headwater stream, then another further downstream that is fed by that headwater stream plus two others. Obviously the pourpoint further downstream is going to share ...
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145 views

ArcPy script stops running randomly with no error returned

I am doing a batch watershed and analysis process on 135 points. This script worked great the first time I ran it. Ever since the first time, however, I have had the script stop at random moments. ...
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31 views

Mean watershed slope - are there better methods than taking the mean of the contained slopes?

I am wondering if there are better methods for determining the mean watershed slope, other than taking the mean of the slope values contained within the watershed? For example, could or should one ...
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22 views

Does Scimap work with QGIS?

Does anybody know if Scimap ( http://www.scimap.org.uk ) works with QGIS? I know it is supposed to operate with ArcGIS and SAGA but as I am very much a beginner with QGIS I would like to know if its ...
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59 views

River channel is cut after rendering flow accumulation in hec-hms

I'm trying to generate flow accumulation using hec-geohms and I have already done some terrain processing using the DEM. I was really confused what happened, why has the river channel been cut? ...
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17 views

Measuring watershed area using pixel accumulation?

I am doing watershed delineation at the continental scale using a GTOPO30 DEM, projected spatial reference WGS_WGS_1984_UTM_Zone_15N. Using Arc10.... My basic workflow using ArcHydro tools: Project ...
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56 views

How to determine irrigable acres from a single source/point?

I am trying to graphically depict the exact amount of irrigable acres from a single point, in this case a headgate from a drainage ditch. Basically, I have the original water right decrees (i.e. ...
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130 views

Error when using r.watershed

When i am calculating LS Factor using Grass r.watershed the error "Raster map or group not found" (image below) keeps turning on. I don´t understand why this error happens if i am using a elevation ...
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222 views

Watershed delineation?

I'd like to delineate the catchments upstream of the sampling points. In order to do that, I have done the following: Burn the rivers into the DEM using ArcHydro>DEM Manipulation>DEM ...
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324 views

Watershed Segmentation SAGA-GIS

I'm trying to segment a topographic map to vectorize it. I'm using the watershed algorithm of SAGA-GIS. It's working fine with polygons, but with roads or contour lines is not working properly. Here ...
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437 views

Stream Order: Strahler vs Shreve

I am writing a research paper on watershed delineation and I am looking for experiences/opinions/authoritative answers on: What guides a hydrologist when it comes to choosing between Strahler's ...
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74 views

How to join two fields after calculating?

I have been working with two layers and I am trying to join them and turn them into a raster data. The first layer is a watershed layer which I have assigned each shed a location from the center point ...
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710 views

GRASS GIS - r.water.outlet - What is my mistake?

I'm new to GIS - more so in GRASS GIS. I installed GRASS GIS 6.4.3svn in my Windows 7 machine. No problem in installation. Downloaded SRTM-Geotiff file Location, Mapset all o.k Used r.in.gdal to ...
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52 views

Simulate water runoff to get water height over each pixel of DEM

Here is my problem that I am trying to deal with. I have given a height map of around 512X512 resolution(It is Geo-referenced and I have the meta-data for this). And I have given that this area ...
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41 views

Extract a specific vertex

I am trying to create catchments/watersheds for each line segment in my stream network. I've managed to get the coordinates for all of the end nodes of the line segments to use as pour points. However ...
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Best Watershed and Hydraulic Models, What is your recomendation?

I am looking to model phosphorus, nitrogen and sediment loads at the watershed and sub-watershed scale in Southern Ontario where the primary land use is agricultural. What is the best model to use? ...
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475 views

Watershed delineation; how to program

I've been trying to roll my own watershed delineation program, taking a flow direction grid and pour points as input. I coded up a quick search algorithm in Python which inspects the flow direction ...
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200 views

What is most suitable DEM to delineate watershed (from spot height, ASTER and SRTM)?

I have three DEMs of our country which are spot height DEM, SRTM DEM and ASTER DEM. SRTM has 90m resolution and ASTER has 30m resolution. My supervisor told me to delineate watershed using these ...
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289 views

Extraction of stream gradient for branched river networks

At the moment I am working on the extraction of stream gradients for a large basin, as a consequence, rivers are strongly branched.So far, I read through the relevant posts on this site, but so far I ...
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15 views

GRASS watershed analysis add storm inlets

Try searching for this with no luck. I am using r.watershed to delineate flow directions, subwatersheds, etc. All good, except that storm drain inlets, culverts and subsurface drainage courses are ...
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41 views

How to separate shared watersheds using ArcGIS for Desktop or QGIS?

I have a similar problem than the one expressed in this question. Here's my situation : I need to have the full watershed of a point downstream of another point.The Watershed tool only gives the ...
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4 views

Does anyone have any specific guidance on incorporating NHD area data into a delineation?

I am working on delineating several watersheds for lakes - and of course the delineations are not perfect. I am new to the Arc Hydro tool, so I am learning about the different Sink related tools that ...
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43 views

Unusual results with Watershed geoprocessing tool

From the starting point of that I already have a flow direction raster and a pour points feature class, I get different results if I execute the geoprocessing tool Watershed using as input the raster ...
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24 views

GRASS GIS 6.5SVN : r.watershed failed to display basin and accumulation maps

I am passing DEM and threshold values as inputs.I want to get basin and accumulation as outputs.I tried it in Grass,process was completed.while dispalying result it is showing white screen (both ...
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151 views

ArcGIS ModelBuilder Clip Raster by Polygon Error

My task is to derive the hypsometric integral and hypsometric curve for a lot of drainage basins. Since it is very time consuming to do this manually, i have created a model (with help from this ...
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59 views

QGIS DEM Output cell size does not match DEM input cell size

As my first post I offer a humble apology if this is such a basic question as to make any of you cringe. I feel like I have exhausted my search skills and read through the QGIS documentation ...