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9

First, you need to calculate at least the slope. F.ex I have the following data: Then put the correct data as variables to the module: And at last you should get the result: UPDATE With Catchment Area as input the results are:


7

The Flow Direction tool in Spatial Analyst only supports the D8 flow direction model, as stated in the How flow direction works page: There are eight valid output directions relating to the eight adjacent cells into which flow could travel. This approach is commonly referred to as an eight-direction (D8) flow model and follows an approach presented in ...


6

Have a look at Crayfish for QGIS http://plugins.qgis.org/plugins/crayfish/ "Crayfish is a plugin (extension) developed by Lutra Consulting for the free and open source GIS platform Quantum GIS (QGIS). The Crayfish plugin aspires to be a complete set of pre and post-processing tools for hydraulic modellers using TUFLOW, ISIS 2D and other modelling ...


6

The GRASS recommendation from @markusN is a good one. Another option, although it's not integrated into QGIS, is the Gerris Flow Solver. GFS is a tremendously powerful hydraulic and hydrological modeling tool. From the site: Gerris is a Free Software program for the solution of the partial differential equations describing fluid flow. The source code is ...


6

The method that I've implemented in a couple of languages and believe that ESRI uses (sorry, no references other than Jenson and Domingue cited elsewhere in this page) is to start at a user-supplied "pour-point" cell or a cell at the edge of the flow direction grid (fdr), examine its eight neighbors to find which of those direct flow into the current cell, ...


4

To expand on my comment: use a combination of Flow Direction and Flow Length to calculate this value. Flow Direction (illustrated below) calculates the direction water would immediately flow from a given pixel. Either north, northeast, east, southeast, south, southwest, west, or northwest. Flow length uses the precalculated flow direction raster to ...


4

With regard to generating hydrologicaly correct elevation models, also called drainage enforced, ANUDEM, remains best of breed to my knowledge. It's the program used to generate the Canadian national elevation dataset (CDED, ironically stored as integer-metres). Also the TopoToRaster tool in ArcGIS uses Anudem under the hood (a revision or three behind ...


4

It will work as a rule of thumb, what you have to consider is the method used by arcmap to calculate flow accumulation. It is based off the D8 method, which assumes that 100% of a cell's input flows out to one of the 8 surrounding cells at the compass points: N, NE, E, SE etc. This works as an approximation but you can't say that such a model would reflect ...


4

Thanks for the reply. I actually figured it out yesterday and hadn't had a chance to mark this as "solved." I had been interpreting the advice on the ESRI forums as the following steps: Create a slope raster, then run the flow accumulation tool on it. Create a raster with a constant value, then run the flow accumulation tool on it. Divide result from ...


4

I would do this (relies on network analysis and PostGIS, but should be doable in ArcGIS, too): relocate the villages and cities to the closest point on the river network line (or create a temporary table for that). In PostGIS, the select query would be something like this: SELECT DISTINCT ON (v.gid) v.gid, v.village_id, ...


3

You can use the following model/workflow to get started: This very basic model yields drainage basins and streams/ephemeral streams from a digital elevation model (DEM). You can expand on this to include watersheds and expanded flow analysis if you care to. From here you should start to see which areas are likely to be affected by point source ...


3

Since the continental divide is determined hydrographically, I would use data from the National Hydrography Dataset (NHD), or the analagous Watershed Boundary Dataset (WBD). Based on this geodatabase of HUC8 boundaries from WBD, the results look pretty good at 1:24,000 scale: This shows Triple Divide Peak in Montana.


3

Sue Greenlee's original code - that Esri's and many other watershed codes are based on - was published in FORTRAN in 1988. I'd go looking for that - don't see it on the web - but you could always email her! Kind of surprised it's not in GitHub, it's pretty neat code. Jenson S. K. and J. O. Domingue. 1988. Extracting Topographic Structure from Digital ...


3

In a conversation following the question, we refined the objective. It is to obtain the watershed area of each point. Some of these points are close to each other, but they are all unique and we would like to determine the watershed area for each point. We will use the watershed area in a predictive model to distinguish a score for each point. The ...


3

If you have ArcGIS 10 and the 3D Analyst, you could use the "Add Surface Information Tool". It populates the attribute table of the Polyline Feature Class/Shapefile with basic elevation and slope statistics.


3

Yes, I would use ArcHydro. I found a document on this page a while ago, that outlines some possible workflows (from the ArcHydro Team). There have been some changes compared to ArcMap 10.0 so for me it was quite useful.


3

whuber has it right. First, get the euclidean allocation. Second, use the minus operation to get the difference between the two. Can be easily done in python.


3

When converting a LiDAR dataset to a DEM, you are taking a set of discrete data points and converting them into a single, continuous dataset. Let's say that your .las file contains X (latitude), Y (longitude) and Z (elevation) values with an average resolution of ~1 meters. The resolution here is really important- we're only talking about an average and so ...


3

This has been asked before, though perhaps in a slightly different context. All of the geoprocessing tools in the Hydrological toolset of Spatial Analyst use the D8 flow direction model, as stated in the How Flow Direction Works page: There are eight valid output directions relating to the eight adjacent cells into which flow could travel. This approach ...


3

The ArcGIS help says: Watersheds can be delineated from a DEM by computing the flow direction and using it in the Watershed tool. To determine the contributing area, a raster representing the direction of flow must first be created with the Flow Direction tool. The Flow Direction is calculated from the DEM using the D8 method, Where the flow is ...


2

Several types of solutions are available. Let's focus on those not requiring any scripting. Raster based In principle the zonal range of each segment gives you the additional information needed to compute slope: just divide it by segment length. (The zonal range is one of the statistics returned by a "zonal summary" of the DEM using the segments as ...


2

Don't know if this will help but I wrote a blog post awhile back on hydro network for 1cm LIDAR DEM. Might have some nuggets for you. http://www.thadwester.com/1/post/2011/03/hydrologic-networks.html


2

Back in college I worked on a project that did this quite well. I am not a hydrologist, nor did I finish the project (graduated), but you might want to check this out: TauDEM 5.0 From what I recall, it worked fairly well. Its a free tool and may be just what you need. Edit: After reading your question more carefully, I believe this is exactly the tool ...


2

you can use the Interpolate Shape tool to interpolate the Z values into the streams. Once you have all the z-aware feature class, you can then add 4 fields, one for x, one for Y & one for the Z coordinate. Use calculate Geometry to populate these values. You can get the Z values that way. You can even graph these values, so as to get a visual profile. ...


2

You can only vectorize lines, not continuous fields. Hence use r.mapcalc with a threshold to extract line structures from that map, then subsequently r.thin. Then it will work as expected. See also this Wiki page for more possibilities: http://grass.osgeo.org/wiki/R.stream.*


2

Check out the NVS Vector Stream Tool which ... is a user-friendly ArcCatalog (9.3.x) Toolbox geoprocessing tool which simply assigns a numeric order to segments of a poly line feature class. Unlike the Spatial Analyst Tools for Hydrography, this tool solely uses vector stream data instead of raster stream data accompanied by a flow direction ...


2

The default for the watershed tool is to limit the output extent to the same as your input pour points. You can change this in the Output Extent (Environment setting) to the maximum of inputs or same as the original DEM. For more info see The analysis environment of Spatial Analyst. Try the Snap Pour Point tool to see if this helps ensure that your crater ...


2

I don't know of a function that does exactly what you ask, but I use Arc Hydro Tools to get the catchment areas and drainage lines. When following the drainage lines it is easy to determine which catchment areas that contribute to each water body (i have cut them out from my dem first, so that they are viewed as sinks in the calculations). After that, just ...


2

Please have a look at Using Viewshed and Observer Points for visibility analysis In the lower part of the article you will see that there are several parameters that you can use. The parameter that you need are VERT1 & VERT2 To use these parameters in your ViewShed Analysis, your input point featureclass should have fields with these names. The ...


2

If you want to calculate streamflow from rainfall/precipitation events, a hydrological model is needed. HEC-HMS is a good & not that complicated model. You can use HEC-GeoHMS (addon for ArcGIS) to generate most of the inputs for HEC-HMS. A very good tutorial for both HEC-HMS & HEC-GeoHMS can be found here ...



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