Questions tagged [watershed]

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

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3
votes
2answers
16k views

Calculate line distances inside of polygons using ArcGIS for Desktop?

I'm working with two data sets: NHD polyline stream layer for my entire state HUC Watershed boundary Polygons for the entire state I am looking for a way to calculate the total length of streams ...
7
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4answers
17k 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 ...
4
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1answer
1k views

Get drainage basin of a polygon (with QGIS, GRASS or other FOSS)

Using a polygon shapefile and a raster DEM, I'd like to find a way to get the drainage basin of a polygon area — that is, the area of all cells which drain into or through the cells contained in the ...
1
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1answer
6k views

How to use GRASS module to delineate watershed area?

Update#1:I changed to work under qgis 1.8, I only input the DEM file and run the r.watershed module, and I got this: I have a DEM file of one specified region, and I take the following steps to get ...
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 ...
3
votes
1answer
952 views

Selecting point to obtain water basin leading to it

For the past few days, I have been working on building a watershed model including drainage basins and find that I am not looking for a global watershed and basin distribution, I am looking to ...
10
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4answers
4k views

What Algorithm is used by ArcGIS Watershed tool?

Does anyone know what type of algorithm is used in the ArcGIS Watershed tool (in the Spatial Analyst package)? Very little information given on Esri's website ... but I suspect it may be some kind of ...
7
votes
1answer
2k views

When computing flow direction, the D8 algorithm is used - are there major differences if others are used?

I am a student working with Hydrological models. Within these models we can route water across a DEM (within a delineated watershed or just within an un-delineated DEM) using many different flow ...
5
votes
1answer
6k views

How to assign correct flow direction to stream network polylines?

I would like to create a map showing the results of watershed analysis as well as the resulting stream network with flow direction. I have a stream network which has been created from the flow ...
4
votes
1answer
498 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
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1answer
396 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) ...
2
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2answers
821 views

How to do the loop when using GRASS module r.water.outlet?

I have seen this post:Watershed Analysis with GRASS, and I have a .txt file which contains coordinates of many points, and I want to use r.water.outlet to get basin area of each point. I type the ...
4
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0answers
334 views

Different watersheds for same area because of “burned streams”

Im trying to analyse where water is flowing which rains down to my project area. This is the DEM I have (my project area is bordered blue, the red marks are my pour points): I learned from another ...
1
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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 ...
8
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1answer
8k views

How to find the watershed area for each point in the river network using DEM?

Update#1: Thanks, Micha, I have followed your instruction and successfully use the modules in GRASS. I use r.watershed to get the basin raster and the drainage line: and I use r.water.outlet to get ...
4
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2answers
506 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 ...
3
votes
1answer
731 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 ...
5
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2answers
147 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 ...
4
votes
1answer
959 views

Watershed extraction using different DEM tiles

I would like to extract the watersheds for a particular area using QGIS. However, I only have Aster 30m DEMs to work with, each tile covering one degree square. The problem is that I need to use ...
4
votes
1answer
346 views

Could bridges prevent ArcMap from creating correct watersheds?

I have a very detailed DEM of a region in Northern Germany. For hours I tried creating correct watersheds but my results all look illogical. Is it possible that bridges disturb the ArcMap Tools? I ...
3
votes
2answers
2k 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. ...
3
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2answers
4k views

Python code to compare two fields in different feature layers?

I have two shapefiles which encompass 3897 features each. Corresponding shapefiles (village and watershed that flows into it) have the same ID (ws_id in one, OBJECTID in the other). Many watersheds ...
2
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2answers
775 views

What are the meaning of Grass drainage direction values from r.watershed

In Grass r.watershed the D8 drainage directions generated from r.watershed are -8. -6.-4.-2, 2, 4, 6, 8 (-1 No Data) What actual directions are these? For example in ArcGIS I know 128 is up and so ...
2
votes
1answer
159 views

r.watershed basins at coast / ocean lines

I am using r.watershed to create watershed basins using a 25*25m dem. The problem I have is that basins are not always created at coast lines. I am experimenting with the parameter "minimum size of ...
4
votes
1answer
143 views

Watershed Tool Straight Edge Problem

I'm trying to accurately delineate a watershed into sub-basins using dams as pour points. I'm using the hydrology toolset, but I can't seem to get rid of straight edges that are along some of the ...
4
votes
0answers
166 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). ...
1
vote
1answer
310 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 ...
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.