The direction and/or volume of something moving across a surface or within a network. Note this tag is primarily for data or function related questions as opposed to cartographic representation.

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35 views

SAGA GIS Channel network crash

So, i had this very weird bug while treating my dem data lately. I used SAGA to create flows channel networks on a dem i acquired a little while ago. Preprocessed it using sink route detection and ...
2
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2answers
58 views

Create curve/arc between 2 points

I am trying to create some visualisations using bus journey data. I am looking to plot journeys along one long road, showing passenge journeys. The principle is the same as a radial flow map for ...
2
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1answer
56 views

Identifying flow of a Wastewater Network

I am trying to identify the flow path of a wastewater system. I am using Arcgis 10.3 and I have set up a geometric network system and identified the sources and the sink (sources = blue dots, sink = ...
3
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1answer
63 views

Color gradient to show direction in polygons (filling, color ramp, gradients)

My data is 2 point-layers: 1 layer origins and 1 layer destinations. I connected these pairs of origins and destinations: firts with lines. As I know that in qgis, there is still no gradient fill ...
2
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1answer
30 views

Flowpath length to stream within catchment

ArcGIS 10.3 provides a hydrology tool "flow length" which calculates the length of flow paths within a basin to the outlet of the basin. I am trying to calculate flow path length and flow path ...
1
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1answer
35 views

Looking for data on river flow speeds

I'm looking for sources containing data on measured river flow speeds, any / all locations worldwide, in any format or language. Googling didn't help much.
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0answers
52 views

Why does the flow direction tool in ArcGIS desktop give wrong output (unique values from 1-255)?

I ran the flow direction in ArcGIS, and received unique values ranging from 1-255. I know that these values are wrong, and should be along the lines of 1, 2, 4, 8, 16, etc multiples. The DEM is ...
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0answers
10 views

Determining flow accumulation to create watershed?

We are looking at sites and trying to determine what level of accumulation to extract by in order to create watersheds. Is there a standard? We cut out buffers (radius of 5000m) around each site.
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38 views

Modelling open water flow in TIN-model using ArcGIS for Desktop?

I have a TIN-model created from 1800 xyz-coordinates (that I also have). There is an pipe leading all the water in and on for all the water out. I would very much like to simulate movement of the ...
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1answer
84 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 ...
4
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1answer
145 views

ArcGIS Geometric Network - Identify Indeterminate Flow

We have a geometric network with sewer pipes that have their flow direction based on digitized direction. Some of the pipes, however, have indeterminate flow. We would like to find all the pipes ...
0
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1answer
55 views

Defining area of influence for origin-destination dataset (where destination is port) using ArcGIS for Desktop?

Starting from an origin-destination dataset for a given country, where the origins are city (points) and the destination are ports (points), how can I identify the area of influence for each ...
3
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1answer
142 views

Problem with flow lines in ArcMap

As a part of my PhD I have to map the rivers of Northern Peloponnese, Greece. I have downloaded two DEMs from Nasa Reverb, which I connected with "mosaic to new raster". I have started the usual ...
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0answers
29 views

Problem with making raster from Aspect and wind direction data [duplicate]

I know its not correct to ask for work flow, but I am learning by doing and now I don't know how to move on. I'm trying to make new raster which will represent the facing sides of hill around a ...
0
votes
2answers
136 views

flow direction and flow length in arcmap

I am trying to replicate a flow length calculation in arcmap 10.2. I have an elevation raster with a pixel range from 0 to 3038.96m (32 bit). When I run the flow direction calculation, the pixel range ...
3
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0answers
161 views

Problem with Flow Direction in DEM

I have the following problem with Flow Direction Tool in my DEM and with such wrong calculated flow direction in the centre of DEM I am unable to delineate any watershed. What can I do?
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0answers
233 views

Flow length analysis only shows pixel value, how to get length?

When I create a flow length analysis, and use identify tool on a cell in the layer, it just shows "stretched value" and "pixel value" I don't understand how it's supposed to show length. I'm using ...
3
votes
2answers
433 views

Understanding flow accumulation

I used this youtube video: https://www.youtube.com/watch?v=FSblORbDyhc&list=PLWJ2X2wvq78QRGzl8Un5ADF0_4m5t99iD&index=11 to learn how to run flow accumulation and was successful. I realize it ...
0
votes
0answers
695 views

Determining Flow Direction in ArcGIS for Desktop?

I have a problem with the Flow Direction tool ArcGIS 10.2.2. After running the tool on a digital elevation model in .tif format 16 bit unsigned integer. However the result is an image of 8 bit ...
2
votes
0answers
199 views

ArcGIS - Flow Direction (Algorithm)

I am curious about the algorithm of Flow Direction in ArcGIS. Recently I am studying about Hidrology, and I have some questions regard to Flow Direction in GIS. The size of this cell is 100m x 100m, ...
2
votes
2answers
396 views

How to extract elevation values at line start and end points from a DEM?

I am new to the whole gis-experience and need your help working with QGIS. I have: DEM raster with heights (3d) line-shapefile which contains the rivers (2d) I need: heights for "start" and "end" ...
3
votes
1answer
420 views

Flow direction and catchment area polygons for utility water pipes

I'm working on a project where I need to show which direction the water would flow from a water pipe in case there is a pipe burst. I also need to show catchment polygons(area affected). This was ...
5
votes
1answer
855 views

Calculate flow path with QGIS

I am trying to replicate my erosion model in ArcGIS for Desktop in QGIS 2.4. I tried to calculate the upstream distance along the flow path for my agricultural field using QGIS. I did the equivalent ...
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0answers
238 views

Asset point IDs, pipeline and flow direction

I have a data set of a sewage pipe network and point data (assets). I would like to: first calculate the flow direction of pipes (polyline feature) assign IDs to the pipelines using asset IDs ...
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0answers
62 views

ArcGIS ArcMap average values in a single flowline

I am newbie in Arcmap. I need to get the average (Velocity) values of 1000 points on my long flowline. I tried to make parallel lines on each gridpoint using the "copy Parallel" function. But there ...
3
votes
1answer
75 views

Exporting massive gps tracks to a map

I have about 1000 vehicle equiped by a GPS sensor and 3G connection. Each vehicle feeds a csv file -using 3G connection- with its current location every 5 sec. Each vehicle have its own CSV file. ...
2
votes
1answer
251 views

How to extract drainage network through gdaldem

From gdaldem I can view slope, aspect, and hillshade maps. "gdaldem slope manj.tif ouoi.tif -p -s 60" "gdaldem aspect manj.tif gg.tif" "gdaldem hillshade manj.tif hh.tif" Is there any command to ...
5
votes
1answer
3k 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 ...
1
vote
1answer
102 views

How to create a barrier feature class to use in a geometric network?

I am working with the NHD and need to isolate stream segments upstream of barriers. I have too many barriers (thousands) to do this manually using the Geometric Network barrier tool on the toolbar. ...
2
votes
0answers
256 views

How to add flow arrows to groundwater table map?

After I had created groundwater table map, I tried using 3D Analyst>Steepest Path to add groundwater flow arrows to the map. However, it didn't work. Would you please let me know how can I add these ...
2
votes
1answer
98 views

When was MFD renamed to FD8?

According to my understanding, the Multiple Flow Direction (MFD) algorithm was originally defined in The Prediction of Hillslope Flow Paths for Distributed Hydrological Modelling using Digital Terrain ...
4
votes
1answer
679 views

Understanding percentage drop-raster (flow direction-tool)

I'm creating a Topographic Wetness Index using a python script (http://arcscripts.esri.com/details.asp?dbid=16750) As I don't want this just to be a blackbox, I'm trying to understand the different ...
3
votes
2answers
2k views

How to display arrows on pipes from upstream to downstream using QGIS?

I am trying to display arrows on pipes of a sewer network so their direction is from upstream to downstream edges of the pipes. I have managed to display those arrows on a polyline layer (which is ...
1
vote
1answer
929 views

Determine use of pipes in a geometric network

I am trying to understand how to use the Geometric Networks in ArcGis 10.1 For the purpose of my experiment, I built a simple network composed of a few connected pipes, one source (left triangle) and ...
1
vote
0answers
936 views

Arrow flow lines from a contour map

using QGIS (or even GRASS) is it possible to label a contour lines shape with arrows that indicate the flow direction? Briefly: I have a point shape with elevation values. I make an interpolation map ...
6
votes
2answers
572 views

R packages for deriving spatial clusters from origin-destination matrix

I have a matrix of origin-destination flows and I am trying to figure out the best way to derive X number of functional spatial clusters from the data. I haven't done this particular type of analysis ...
4
votes
2answers
267 views

Can ArcHydro tools be used on a network in an SDE enterprise geodatabase?

Most of the documentation for ArcHydro tools discusses their use on data in ESRI's personal and file geodatabases. Is it possible to use ArcHydro tools to set network flow direction on a networked ...