Questions tagged [flow]

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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12 views

ArcGIS tool which shows all cells a point flows into?

Is there a tool that is effectively the inverse of flow accumulation of a pour point - as in, if I have a specific point that is the site of potential pollution, is there a tool which will show all ...
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0answers
36 views

Align arrow (point layer) to water direction (line feature)

Assuming that pipes are digitizet correctly (first node as upstream, last as downstream), I need to align the arrows of a point layer to display flowmeter's direction. So far I need to use v.split (...
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1answer
177 views

Arrow head at the last path segment of Bezier curve

I am making a flow map. For most flows, I used the curved arrow symbology associated with lines. For my Mediterranean flow, I have to draw a path that ends with an arrow. I use the Bezier plugin to ...
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74 views

Manually adding centroids to arrows in Virtual Layers in QGIS

Currently, I'm making a map that depicts the migration flows of people who have finished their university degrees and decide to move to a different Dutch city after their studies. By following Anita ...
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1answer
53 views

r.terraflow fails after using fill-sinks

I'm using QGIS 3.10.11 with GRASS 7.8.4, and the default SAGA version that's included with the QGIS standalone 3.10.11 installer from QGIS.com. I'm having an issue where r.terraflow fails after using ...
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25 views

Data flow documentation tool

I am in the process of mapping the journey of our data through the different apps used by our service. We use an ArcSDE geodatabase as main data source. This data is viewed in ArcMap edited with ...
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1answer
406 views

Adding arrows to hydro line to show direction that river is flowing using ArcGIS Pro

I have a large number of rivers and streams on my map which do contain elevation data in the attribute table. I would like the lines on the map representing the rivers to have small reverse arrows ...
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24 views

Identify false outlets on a river network

I have a river network that is very poorly defined (lots of gaps). I need to identify all the false outlets. The picture below provides an example of one of these false outlets. The image shows ...
3
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1answer
442 views

Flow accumulation on grid in R

I would like to calculate the number of cells from gridded elevation data that drain into a particular cell. First, I calculate the flow direction by selecting the cell with the steepest slope from ...
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1answer
331 views

Generating slightly curved arrows in QGIS 3

In Geometry Generator in Symbology in Layer Properties, the following expression works, but the result is not satisfactory due to the middle point fixed coefficient 1,1: make_line ( start_point(...
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1answer
108 views

Flow data distribution within features of overlapping layers

I want to improve/adjust/comprehend the formula (see below) that was used in my previous question: Transferring flows (connections + values) between polygons for calculating flow values of mobile data ...
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52 views

Flow Distance Not Calculating for Entire Raster

I am trying to calculate the height above the nearest stream for an area. The problem is, it only does so for a portion ( the colored area below) of my area of interest. In the pic below, the black ...
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1answer
28 views

Listing grid cell numbers for outlet according to flow direction using ArcGIS Desktop?

I am trying to list grid cell numbers whose flows contribute to the red cell I draw in the figure according to the known flow directions. Directions and colors are shown in the figure. What tool can ...
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2answers
551 views

Transferring flows (connections + values) between polygons

In QGIS there are two shapefiles representing the moving data between cells and one additional layer, see image below Moving data defined by: Polygon "LayerA" (transparent squares with red outline)...
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1answer
115 views

Getting angle of point generated from DEM in Raster using Field Calculator in ArcGIS Desktop?

I am trying to calculate the angle of some specific points generated from flow direction in ArcMap 10.2. I converted the DEM to flow direction and then to points. I am trying to convert the grid_code ...
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146 views

Generating flow path using r.drain from rgrass

I need to generate the flow path using r.drain from the rgrass7 package in RStudio. I am new to GRASS GIS and prefer to use the R package instead. I want to generate a flow path from a grid cell. ...
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1answer
126 views

How to extract a flow chart from points connected with lines?

I have some points connected with arrows, like the following example: How can I extract a flow chart like the following? I tried to use the flowMapper plugin but it seems it is not what I want.
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1answer
983 views

Showing overland flow route on DEM in QGIS?

I've been asked to produce a risk map at work which will show the possible flood route from sewers that surcharge (flood) during heavy rainfall. This is basically where I know the x-y coordinate (OS ...
3
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1answer
155 views

Why TauDEM specialized tools (e.g. D-Infinity Distance Down) are only available with D-Infinity flow model?

I would like to know why most TauDEM specialized tools have been developed just for the D-Infinity flow model. Is it because the D8 would not make sense for these algorithms, or they just have not ...
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1k views

Displaying flow direction raster in QGIS?

I have a raster with flow directions (geotiff). In ArcGIS I can use the vector field symbology option to display nifty arrows (see image). Is there a way to accomplish something similar in QGIS? I've ...
2
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1answer
922 views

Longest flow path in QGIS from single feature vector

I have got a vector layer with one feature (MultiLineString) representing a river network (s. below) without bifurcations. In addition there is a point shapefile containing the outlets of different ...
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0answers
265 views

r.flow in QGIS 2.16.1 generates wrong output

I try to run the r.flow module to get the flow path length of my layer out. The input Layer is a DEM with pixelsize 0.0083 and the selected CRS (EPSG:32646, WGS 84/ UTM zone 46). First of all I ...
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1answer
1k views

Determining flow path length in QGIS?

I need help with qgis flow path length. I try to run the program and when I run the program I get a raster with 0 values, as input I'm using filled raster, I don't now if I'm doing something wrong or ...
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2answers
256 views

Edit RGB values of 0,0,0

I am VERY new to ArcMap and GIS in general. I converted some lidar data to a GEOTIFF, using a program called CARIS (it was an .csar file) and imported this into ArcMap. There are some areas that are ...
2
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1answer
90 views

Interpolation of river pollution data

I have 6 samples of water quality parameters taken on a 10 km stretch downstream (Cooum River in Chennai), so it's basically the estuary. The river discharge and flow is extremely low, therefore I ...
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3answers
3k views

How to display Flow Direction arrows + Burn Stream Netwok in QGIS?

I have used the automated r.watershed tool in QGIS 2.18 (GRASS plugin) to conduct a watershed analysis (basin boundaries, flow direction, flow accumulation etc). I'm stuck on the following operations:...
6
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1answer
1k views

Flow Path length

I'm a student and pretty much new to QGIS, GRASS and SAGA tools. I'm trying to calculate the longest flow path length using SAGA "flow path length" module in Qgis. Using the default parameters: I'...
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1answer
238 views

Use of the Peclet number in FEFlow as a mesh-quality metric

The user manual for FEFlow (v7.0) states "In transport models, the elemental distribution Péclet Number is available which can be used to check whether the spatial discretization is ...
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0answers
355 views

QGIS Multi-Basin Delineation (Pour-Point) Hydrology

I'm working on a QGIS plugin and struggling to find some existing QGIS processing functionally I could leverage. I need to replicate multi-basin delineation using pre-defined pour points. Specifically,...
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1answer
118 views

Summing values of grid moving upstream along flow paths in GRASS

I would like to sum the values of a grid, moving upstream along flow paths. In other words, I have a grid A with a value for each cell. I need to build a new grid, B, in which the value of each cell ...
3
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0answers
560 views

Show flow direction for pipes as arrows in QGIS [duplicate]

I have a vector layer (line features) which consists of different pipes. In the attribute data I have fields that indicate the upstream elevation and downstream elevation values. I am trying to ...
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2answers
215 views

Incorrect length from Flow Length tool

Why is my flow length tool giving value less than one? Isn't a flow length tool supposed to give the maximum length of upstream flow to the cell? Then, how come? I am using coordinate system of GCS ...
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2answers
285 views

Understanding hydrology and DEM results?

In first picture, you can see an image of a lake(Bellandur lake, bengaluru, india). In second picture, you can see the flow accumulation data for the same area I made(after "fill"ing the sinks). As ...
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0answers
82 views

Finding vectors with wrong direction in river network

I have a shapefile containing network of rivers for the whole country. The description of the layer is saying that orientation of the vector should be the same as the river flow. This is true for most ...
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1answer
126 views

Fast, simple assignment of flow directions to flats in GRASS

I have some enormously huge DEMs which I'd like to assign flow directions to. These DEMs are guaranteed to have no sinks, just flat areas. It seems as though the only ways of assign flow directions ...
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0answers
135 views

Map library supporting linestring curve rendering to produce flow map

Is there some function/plugin for any javascript map library (OL, leaflet, ArcGIS API for JS) to render WFS or Geojson LineStrings not as simple line but as curves? I want to make mobility flow maps ...
2
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0answers
443 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
1k 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
826 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
1k 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 for ...
3
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1answer
849 views

Calculating flowpath length to stream within catchment using ArcGIS Desktop?

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 ...
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1answer
66 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
493 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
104 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 ...
2
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2answers
1k 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 ...
5
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1answer
533 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
241 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 ...
4
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1answer
882 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
40 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 ...
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2answers
656 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 ...