I'm new user of this software, please can somebody guide me, how to calculate stream order in QGIS or GRASS GIS, step by step.... mean commands and how to calculate watershed in this.

  • What have you tried? Where are you stuck? Please edit your question to provide more details as advised when you initially posted this as an answer to another question.
    – PolyGeo
    Jan 26 '15 at 9:37
  • I told you m just new user of this software mean, this is my first time to download and installation of this QGIS. I have created watershed area with ARCGIS 10, but ARCGIS can not measure all stream orders, e.g Horton, topology etc. please just guide me step by step to creat Horton stream order and other just like Strahler, Shreve in ARC GIS 10, we follow the steps FILL, FLOW, ACCUMMULATION etc. same procedure are available on youtube for this. But I could not find anthing like this video about QGIS, that can teach me step by step Horton and others calculation QGIS Feb 7 '15 at 17:29
  • If you are only interested in how to do this in QGIS now then please edit your question to say that and focus on just one type of stream ordering first. Otherwise I think your question is far too broad.
    – PolyGeo
    Feb 8 '15 at 7:04
  • well, thanks for your positive reply, guide me step by step how to calculate Horton stream order, and watershed delineation. Feb 8 '15 at 15:38
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    I think it would greatly facilitate our volunteers to help you if you could review How to ask a good question? and then use the edit button beneath your question to improve it with some of the content you seem to be trying to discuss as comments.
    – PolyGeo
    Feb 8 '15 at 21:24

I have calculated stream order with the SAGA GIS module. You can read about the modules here: http://www.saga-gis.org/saga_module_doc/2.1.3/ta_hydrology.html All this assumes you have an elevation model in GeoTIFF.

In order to get that working you need to install QGIS with the OSGeo4W installer and make sure SAGA GIS is checked for install:

Installation options to get SAGA

Then you have an assortment of hydrology tools ready in the processing toolbox. In order to calculate a drainage route network on overland flow you need to fill in all the small holes of the DEM (so the stream simulation doesn't get stuck.) I used Wang & Liu's method for this:

Wang & Liu in SAGA processing list

Now you will have rasters for a filled elevation model, as well as watershed basins and flow directions. Then you can perform a Sink Drainage Route detection on the filled DEM:

enter image description here

This will give you a shapefile with the drainage routes, with an attribute containing their Strahler order. Very useful. Good luck!

  • but I want to do this r.stream, in this all streams available, please can u help me in this egard Feb 7 '15 at 17:53
  • I'm sorry, but I haven't used GRASS for this sort of work. You might want to consider rephrasing your question to describe exactly what kind of analysis you are trying to do.
    – hexamon
    Feb 9 '15 at 7:47

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