Questions tagged [watershed]

Use this tag when asking a question about a watershed related to GIS environment.

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3
votes
1answer
246 views

Watershed-segmentation with orfeo toolbox

I work at the moment with the watershed-segmentation from the orfeo-toolbox. After the segmentation the pictures is split into squares. Specially the square in the middle seems to be deeper the the ...
1
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0answers
322 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
241 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 ...
2
votes
1answer
296 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
53 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 ...
1
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1answer
418 views

Watershed analysis using GRASS GIS

I have Contour lines shapefile which I imported that into GRASS and converted to a DEM using the IDW interpolation technique (r.surf.idw with npoints 250). Now I want watershed analysis to be done ...
1
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0answers
103 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 ...
3
votes
1answer
750 views

Can't get GRASS r.water.outlet to work

I'm new to GRASS. We want to delineate a watershed using the LIDAR data we have our hands on. I tried to follow several procedures to do so, but despite all my efforts, I can only get it to select a ...
1
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3answers
723 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
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1answer
53 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
65 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 ...
2
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1answer
53 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
557 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
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0answers
133 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
0answers
49 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 ...
4
votes
2answers
126 views

Getting 8 digit watersheds for USA

Is there an alternative source for 8-digit (vector shapefiles) US watersheds? The USDA link is down and they are not responsive to my query for getting the data: https://gdg.sc.egov.usda.gov/
4
votes
2answers
9k 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 ...
8
votes
4answers
18k views

General steps to create watershed boundary in ArcGIS Spatial Analyst?

I am an ArcGIS beginner. I have a CD of GIS files of a city and intend to work on watershed management. There are different file names in different formats on CD. Like .shp, .shx, .dbf, .sbx. and ...
1
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0answers
68 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
584 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 ...
4
votes
0answers
177 views

Watershed delineation with meandering river?

I'm using ArcGIS (Hydrology toolbox) for watershed delineation for a number of pour points, and I'm running into problems with very meandering rivers on extremely flat alluvial land (Amazon basin). ...
3
votes
1answer
758 views

Delineating large scale watershed?

I would like to do some watershed delineation at national/regional level (using SRTM-90 data). I have experimented with r.watershed (GRASS 6.4.3) but it fell over when I tried to do big stuff. I ...
1
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0answers
63 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 ...
0
votes
1answer
914 views

Efficient algorithms for recovering watershed boundaries?

This is somewhat related to a previous question I asked: What Algorithm is used by ArcGIS Watershed tool? I was wondering if there is a more efficient way to calculate catchment areas if you are ...
1
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0answers
148 views

calculate flow accumulation in a river with two outlet points

I'm trying to calculate flow accumulation layer (with arcGIS) in a basin with 2 outlet points. I have used "dem reconditioning" tool to modify my dem according to a vector layer, which contains my ...
1
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0answers
120 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
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0answers
228 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
459 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.
0
votes
1answer
436 views

Understanding Drainage Density?

I have calculated drainage density for two watershed and need to make sense of the numbers. One watershed has a drainage density of 1.08 km/km2 (area=32 sq. km and total stream length=34.436 km). The ...
0
votes
1answer
363 views

Making rivers with higher Strahler/stream order wider in QGIS?

I have a river network and the Strahler order of all rivers in it. Now I would like to create a map similar to this one http://www.hydrosheds.org/, i.e. with rivers of a higher Strahler order being ...
1
vote
1answer
117 views

Using NLCD to quantify rate of urban sprawl in a watershed

I have downloaded five datasets and would like to quantify the rate of urban sprawl in a watershed from 2001 to 2011 using NLCD. Here is the data I have: (1) NLCD 2001 to 2011 Land Cover from to ...
1
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0answers
235 views

What channel initiation threshold value should I use when creating a stream network for drainage density calculation?

I need to calculate drainage density for two southern AL watersheds (D’Olive and Fly Creek). What channel initiation threshold value should I use when creating the stream network? I am following ...
1
vote
1answer
906 views

Watersheds tool does not create watersheds in ArcMap?

I`m trying to create watersheds and every time I run the Watershed tool, the result will be very interesting. I use snap raster and I set the extent of the output to the extent of the flow direction ...
3
votes
0answers
359 views

ArcHydro catchment area of specific stream segment

I am given the task to create the catchment areas of specific streams/lakes. To sum it all up, I am looking to find the catchment areas for lake 1, stream, lake 2 and downstream of lake 2 all ...
3
votes
0answers
1k views

Using WATERSHED to delineate tree crowns in ArcGIS Desktop? [closed]

I'm trying to delineate and count trees from a DSM/DTM generated from a UAV survey. It's from a citrus grove where trees are growing in different spacing. I have developed a workflow that works for ...
3
votes
1answer
113 views

Drainage basins ignoring lake

This is my first time writing in this forum and I hope this question offers some quality of information easing a solution. Here goes. I am new in analyzing hydrology with DEMs and I have followed ...
4
votes
1answer
593 views

Does r.stream.basin still exist? GRASS-QGIS2.18.7

So I'm following steps in another topic that seems to date to January of this year and is exactly what I want to do, here's the link: Get drainage basin of a polygon and at one of the last steps in ...
2
votes
1answer
439 views

drainage basin for whole lake QGIS 2.18.7

I am currently facing a problem. Over the past week, I have been initiated to hydrology within the GIS environment and have finally successfully generated water basins (using the GRASS r.water.outlet) ...
1
vote
0answers
159 views

Error while using Watershed tool

I was trying to create watershed from a DEM that used polylines. So I converted that to raster and the raster to TIN. I delineated the TIN to fill the gaps and then returned it to raster. Then I got ...
2
votes
3answers
3k views

Automatic Watershed Delineation in ArcGIS Desktop and Arc Hydro?

I am trying to delineate watersheds automatically using Arcgis/Arc Hydro. I got the drainage area contribution of stream segment (part of stream) as shown in figure stream. The corresponding drainage ...
0
votes
1answer
767 views

From DWG to Shapefile: How to extract the channels length of water courses?

I have a DWG file with the drainage system of a small town. I need to open it on ArcGIS and get the total length of the channels that are part of one of the watersheds in the city. When I convert the ...
1
vote
2answers
2k views

Calculating watershed runoff with landuse and rainfall data?

What is the method for computing rasters of total rainfall of a given month, flow accumulation, and land use (runoff coefficient) or soil K factor? I am using ArcMap 10.
1
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0answers
95 views

Adding curb/gutter and subsurface storm drain networks to watershed analysis in QGIS

I need to do a neighborhood scale drainage analysis. The analysis needs to accurately show the drainage area to each storm drain inlet. Using GRASS on QGIS 2.12.1 on OS X, I have been able to ...
8
votes
1answer
739 views

Basin creation GRASS vs. flow direction

I have a strange behaviour in QGIS with GRASS tools. I am trying to create basins in the alp region and use he SRTM3 data. As I can see on the flow direction raster the SRTM3 data seems to act nice: ...
4
votes
3answers
5k views

How to find out the Basin Length?

I am doing Project on Drainage basin, to find out the Elongation ratio I need to find out Basin length, Can any one of you tell me how to find out BASIN LENGTH using ArcGIS or any other way. My data ...
-1
votes
1answer
323 views

Cumulative delay function for rainfall-runoff modeling using TOPMODEL [closed]

I am trying to model rainfall-runoff using TOPMODEL in R. The TOPMODEL needs an input called "cumulative delay function". The R documentation says "Flow is routed through a delay function which ...
0
votes
1answer
130 views

Combining small watershed in a better way

I used grassgis delineated watersheds in a large area. After vectorizing the watershed raster, I ended up with a lot of tiny watersheds. "Dissolve" did help a bit, but there are about 1200 ...
1
vote
1answer
4k views

How to indicate flow of a watershed feature?

While tracing and digitizing rivers, streams, rivulets, etc., is it possible to indicate the direction/flow in the shapefile on QGIS? I'd like to avoid using map labels. Ideally, when done tracing, I ...
2
votes
1answer
276 views

Smoothing/Aggregating polygon in ArcGIS Desktop?

I have this one big polygon separated by a big gap/space like this Can anyone advise how can i edit, so that the space should be narrow, smooth without a big gap like this? What function should i ...
1
vote
1answer
325 views

Python code to select streamlines within selected watershed

I'm trying to calculate total stream length for multiple, overlapping watersheds (i.e., each watershed contains the watersheds upstream of it). I have a flowline layer that I've run through the ...