Not to be confused with hydrology, hydrography describes the spatiotemporal distribution of water bodies and their features.

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4answers
371 views

What satellite imagery would help to show spring locations?

I've got lots of tiny streams on a hydrography shapefile. Historic texts indicate that certain ones have headwaters at "sources" or springs, and I want to try to find these. Browsing the historical ...
1
vote
1answer
83 views

Which File to load from National Hydrography Dataset?

Start-over beginner here. I'm using QGIS 2.0 on MacBook with OS X 10.8.5. I downloaded a National Hydrography Database file. Unzipped, it is titled NHD11032_NM.gdb. I try to add the layer as a vector ...
4
votes
1answer
97 views

Is there a downloadable data source for mapping out rivers with names for the whole world?

I'd like to be able to extract rivers with their names and the flow size (not direction) for the whole world. The scale I'll be drawing it at is about 2 centimeters per 10 real world km - nothing too ...
0
votes
1answer
65 views

merge national hydrography dataset files

I'm having difficulty merging datafiles from the NHD while still keeping functionality as a geometric network. I'm using ArcGIS 10.1, so the USGS merge tool isn't an option. Using the medium ...
3
votes
1answer
91 views

Is there an easy way to taper huge amounts of drainage vectors?

I've performed hydrological analysis using r.watershed using GRASS and now I have some stream vectors for a large area. Next, I'm planning to taper these streams to varying width to make them appear ...
6
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1answer
2k views

Calculate Topographic wetness index in SAGA

i am currently working on a project which involves the quantification of the wetness in certain areas. However it produces quite different results from what i expected. I'll describe the steps i have ...
1
vote
0answers
217 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 ...
8
votes
4answers
4k views

How to 'burn' a stream network into a DEM layer in ArcGIS 10?

I am working on a DEM that in an area where there is little relief. I would like to 'burn' the river network into the DEM so I can calculate flow accumulation and flow length accurately. I am using ...
4
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1answer
1k views

Stream Gradient - two types - using NHD high resolution data

I need to calculate slope, or stream gradient, two different ways: 1.) Main channel slope from the pour point to the head/source point along the vector stream network 2.) a local slope consisting of ...
8
votes
2answers
2k views

Workflow for determining stream gradient?

As far as data goes, I'm working with NHD .shp files, 10m DEMs, and some LIDAR data. My goal is to determine gradient for 100m segments of a network of streams. I'm already able to do this, but I ...
6
votes
1answer
640 views

Is there a way to get the percentage of different landuse types upstream of a given point?

I'm a fairly novice GIS user and know just enough to get in trouble in a lot of cases. I am trying to look at the connection between several measured parameters at a few hundred stations along ...
4
votes
1answer
1k views

Processing time using ArcGIS Hydrology toolbox tools in standalone Python script vs. ArcCatalog

My question is: what might cause the ArcGIS 9.3 Hydrology Toolbox Snap Pour Point and Watershed tools to run significantly slower in a Python script versus manually running the tools in ArcCatalog ...
10
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1answer
601 views

Error assessment of calculation done using unprojected vs. projected data

This question builds off of the one with the subject line "Calculating Flow Direction and Delineating Basins from Projected vs. Unprojected Data.": Calculating Flow Direction and Delineating Basins ...
16
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1answer
3k views

Calculating Flow Direction and Delineating Basins from Projected vs. Unprojected DEM Data

This is somewhat of a theoretical question stemming from some discussions with colleagues on the topic of implications with delineating basins with projected (e.g., Albers Equal Area) vs. unprojected ...
1
vote
1answer
545 views

Is there any pseudocode for MFD (multiple flow direction) algorithm available?

Still stuck with the simulation system, is there any good pseudocode for the multiple flow direction (MFD) algorithm? I read a pseudocode example and implemented it, however the simulation was linear: ...
3
votes
3answers
1k views

River drainage basin boundary

I'm looking for a set of outlines of the river basins in the UK - I don't need a particularly detailed or highly accurate map - just a map saying point X will drain into the Thames or point Y will ...
8
votes
4answers
991 views

Flood modelling insights

I am trying to create a flood modelling system. The system consists of two parts mainly a river flooding simulation and rainfall simulation. To do this I am running the latest version of GRASS 6.4. ...
1
vote
1answer
268 views

Error in r.terraflow

I used r.terraflow.short in GRASS, but it displayed this error: r.terraflow.short elevation=raster_bulacanElevation \ filled=raster_bulacanElevationFlooded1 \ ...