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Questions tagged [flow-accumulation]

In hydrological modelling, flow accumulation shows water collection based on flow direction. Flow accumulation is used to generate a drainage network

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Howerive vector stream network from a DEM using D-Infinity Flow Direction algorithm?

I have been working with a 1m LiDAR derived DEM to create a vector stream network. Using the D8 flow direction, D8 flow accumulation, and a specified threshold, I was able to create a vector stream ...
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22 views

Understanding ArcGIS Flow accumulation result?

I have modified an existing DEM to produce two sinks - the brightest pixels, both with a dot drawn on them below. I have verified that they are, in fact, the lowest points with the ID tool and have ...
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1answer
105 views

Choosing Topographic Wetness Index or Flow Accumulation raster?

What is the better raster to use qualitatively - Topographic Wetness Index or Flow Accumulation - to clearly see potential areas of surface flow/wetness across a landscape? As an example, what's "...
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82 views

Determining flood extents based on a daily flow? [closed]

I have a DEM raster and daily average flows (e.g., 50Ml/day). And I want to determine how far the water extent goes when the flow accumulates for 7 days based on 50 ml per day?
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1answer
122 views

tauDEM flow accumulation (D8 or D-infinity) results is NA-values for some major rivers

I am having some trouble with tauDEM that I am hoping someone can give me some advice on. I'm running tauDEM via command line through R-studio. I am working with some 30m resolution SRTM DEM data in ...
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34 views

Comparing aerial photography with stream network (flow accumulation tool)?

I have obtained a stream network for my study area (in southern Uruguay, South America) from a DEM using the Hydrotools from ArcGIS. I want to determine a flow accumulation threshold comparing my ...
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2answers
158 views

How to create “roof line” for a general polygon area?

I have a polygon with an arbitrary shape ( assume that it is well-formed with no self intersection, no duplicated points etc), and I need to subdivide the polygon into sub-polygons like how one would ...
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1answer
88 views

Rainfall-weighted flow accumulation

I am perfoming a geospatial process whereby I want to use the flow accumulation (as an input for discharge proxy) in calculating stream power. I am using ArcGIS 10.2 So far I have: 1. Valley/channel ...
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1answer
43 views

Are there any continental-scale flow accumulation products besides Hydrosheds?

I am trying to compute branching angles of drainage networks for roughly the western half of the U.S. Because many of these streams are non-perennial (don't have water all year), some of the standard ...
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2answers
365 views

Is D8 flow accumulation algorithm still suitable for watershed computation if terrain contains lots of flat area?

My question is inspired ( and similar) with my previous question. But this question is more concerned about the suitability of D8 ( or in general non-dispersive) flow accumulation algorithm for ...
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2answers
126 views

Does the common flow accumulation techniques still work over flat area?

My terrain is a highly developed area--which means that It involves lots of flat area ( gradient=0) because they have been properly paved. And it involves sudden drop, such as retaining wall, or ...
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1answer
144 views

Flow accumulation algorithm open source code in C++ on Windows

I'm looking for flow accumulation open source implementation ( C++ or C# would do, Python no), on Windows, preferably the source code comes with Visual Studio project files so that I can just build ...
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2answers
110 views

How can the flow accumulation in a hydrological model/stream network be maintained across tiles of a large area of interest?

My study area is too large to be processed in its entireity by any hydrological modelling software I have found yet. I will have to break it up in to smaller areas, but there will be flow across these ...
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1answer
129 views

Flow accumulation map giving zero values

I have applied the flow accumulation tool in arcgis 10.5. The results map has zero values in places that it should not, which makes the further processing of my images wrong. Any idea why this ...
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84 views

Setting maximum slope/flow length in flow accumulation using SAGA?

I like to limit the slope length in SAGA GIS. In other words, the flow accumulation should only account for a specific length until a subsurface flow initiates and surface flow stops. Actually, I ...
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2answers
345 views

Compute flow accumulation only from flow direction?

I am looking to calculate flow accumulation from a flow direction raster. In ArcGIS there is Flow Accumulation (http://desktop.arcgis.com/en/arcmap/10.3/tools/spatial-analyst-toolbox/flow-accumulation....
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2answers
167 views

Straight lines as output of flow accumulation in ArcMap 10.5

I'm quite new to ArcMap and I have a question regarding the flow accumulation tool. What I did so far: converted TIN into raster (sample_distance/sampling_method distance: CELLSIZE 1 m) calculated ...
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2answers
147 views

Performing Weighted Flow Accumulation in GRASS?

I would like to calculate a weighted flow accumulation raster with GRASS. I have a DEM and a rainfall raster. I am looking to calculate the rainfall accumulated downstream. Basically, it is similar in ...
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3answers
477 views

Doing watershed delineation properly using ArcGIS Desktop?

I am using ArcGIS Desktop 10.2. I have the contours and the stream in AutoCAD Civil, after converting to a shapefile, I exported them in GIS, after I created the TIN from the contours below: ...
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147 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
270 views

Flow Direction created from depressionless DEM inaccurate in flat areas

I am trying to build a flow direction raster for an area from a 1m DEM created from LiDAR. I need this in order to build a flow accumulation raster, so I can use that to build a stream network. I have ...
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2answers
160 views

Figuring downhill gradient slope to riparian area on ArcGIS 10.5

I am currently working on constructing a countywide riparian area, which normally consists of the integration of water bodies, wetlands, wildlife corridors, flood prone areas and hydric soils. We ...
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1answer
182 views

Error running TopologicalBreachBurn in Whitebox GAT

I am trying to execute the TopologicalBreachBurn script in Whitebox GAT. This is my first time using this software so am generally unfamiliar with how it operates. I imported a DEM as an ASCII .txt to ...
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140 views

How to use GRASS command “r.stream.distance” in Qgis 2.16.2?

I like to figure out the distance from each cell to the outlet along the flow path. Maybe you can suggest some other opportunities/commands to solve my problem. It would be nice, if someone can help ...
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113 views

How to compute accumulated material flowing into downstream grid in ArcGIS/Python?

Does anyone know how to calculate for each cell the accumulated amount of material that flows out of the cell into its neighbouring downstream cell in ArcGIS/Python? This accumulated amount is the ...
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1answer
115 views

Problem with Pygeoprocessing since upgrading to version 0.4.4 from version 0.2.2

I need to calculate D-Infinity Flow Direction on my input raster (geotiff). I use pygeoprocessing for this. Since I uninstalled the version that I had (0.2.2) and installed a newer version of the ...
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1answer
217 views

Getting wrong values of Flow direction in ArcGIS?

I am trying to generate flow direction from DEM. However I am getting some vales as 80 and 129, though it should be only from 1, 2, 4, 8,16, 32, 64, 128 What could be the reason for this error? How ...
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33 views

ArcGis Tool box for generate raster of runoff “final area”

I have 1 single runoff raster file (and DEM). I need this runoff to "drain" to the lowlands or valleys. For this, generally hydrographs are made outside the arcgis program. I only need this last ...
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2answers
88 views

Creating DEM using ArcGIS Desktop?

I am new in this field and I am having a problem with my DEM, (SRTM 30M). When I calculate flow accumulation a straight line appears if I fill the DEM. And rivers are not connected if I don't fill ...
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0answers
88 views

Multiple flow distance rasters produce low distance values along catchment boundary [closed]

My problem makes use of ArcGIS tools generally and Spatial Analyst in particular, but my question has more to do with hydrological modelling and working with DEMs. My goal is to obtain flow distance ...
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1answer
97 views

Calculating Flow Direction using ArcMap with mixed X,Y,Z units

I have a DEM in UTM that I am converting to a StatePlane coordinate system in feet. This raster is going to be used to generate watershed delineations - therefore I will generate a flow direction ...
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421 views

Getting huge range of values when using Flow Accumulation tool in ArcGIS Desktop?

I'm trying to use ArcGIS Desktop to delineate watersheds for a series of sampling sites. I've been following the protocol laid out by WhiteboxDev in General steps to create watershed boundary in ...
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1answer
406 views

Distance to nearest flow channel

I have a problem where I need to, for each cell, calculate the distance to the nearest flow channel. This is likely a complex problem due to the fact that I need the nearest flow channel while ...
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2answers
156 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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139 views

calculate flow accumulation in a river with two outlet points

I'm trying to calculate flow accumulation layer (with arcGIS) in a basin with 2 outlet points. I have used "dem reconditioning" tool to modify my dem according to a vector layer, which contains my ...
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3answers
965 views

Error in r.thin Qgis GRASS : Input raster must be of type CELL

I am getting the following error from QGIS GRASS GIS r.thin module ERROR: Input raster must be of type CELL. The input file is a simple file of 0 and 1 that represent a drainge network. I obtained ...
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0answers
637 views

Flow Accumulation and Flow Path Error from Flow Direction Raster in ArcMap? [closed]

I am trying to generate a flow accumulation and flow length raster from flow direction. I have successfully generated a flow direction raster from a DEM that was clipped by the 'Clip (Data management ...
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1answer
262 views

How to define pour points from a stream network at a barrier for watershed calculations?

I'm looking for a way to check if cells from one raster file have contact or get close to cells from a second raster file. For example the blue raster is a barrier and the coloured is the flow ...
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3answers
2k views

Flow Accumulation Python or MATLAB Script

does anyone have any resources for scripting the D8 flow accumulation in Python or MATLAB after obtaining the flow direction values and filling in 'sinks' and 'flats'? I am trying to understand the ...
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0answers
261 views

Calculating flow distance of pixel from outlet using R?

I have created these raster files for a river basin: DEM Flow Direction Flow Accumulation Also, I have another raster with values of rainfall. All the 4 rasters have same spatial extent, ...
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0answers
213 views

Preventing flow accumulation in one watershed from traveling up tributaries into adjacent watersheds?

I am using TauDEM in ArcMap 10.3.1 to try and calculate flow accumulation and generate stream networks for HUC10 watersheds. I am using 3m DEMs acquired from the National Map. The HUC10 I am working ...
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1answer
224 views

Zonal maximum at a specific location

I have 50,000 polygon shapefile, each polygon is a small community. I have a flow accumulation raster. I need to extract just the maximum cell (max flow accumulation) for each polygon. Now if I run ...
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1answer
482 views

Does this ArcGIS flow accumulation example have an error?

The lower right corner of the flow accumulation example in ArcGIS Desktop's documentation has a flow accumulation value of 2. However, I only see one cell flowing into the lower right corner (the ...
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0answers
152 views

ArcGIS 10 restricted WEIGHTED Flow Accumulation [closed]

I have a question very similar to one asked by wxfox4god on 12th June 2013 ("Arcmap 10 restrict Flow Accumulation") that was answered by whuber. (I have had to post it as a new question as I do not ...
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0answers
349 views

Cumulative length of polylines [closed]

I have a polyline shapefile with streams. I would like to turn this to a raster where there would be a cumulative length sum value in each pixel moving downstream. In other words, this would be an ...
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0answers
662 views

Fill tool settings in ArcMap? [closed]

Specific question on Fill tool in ArcGis 10.2.2, I got a filling problem, I think holes are not fully filled when I use the fill tool, how do I change that ? 2 images of the same area for an example, ...
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1answer
1k views

How to calculate “water accumulated in each cell” using QGis?

I create channel network and catchment area from a DEM with SAGA GIS. I know that flow is starting from a cell to an other cell. Firstly, a cell is filled with water and then it is starting to flow ...
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0answers
338 views

Consistent errors with flow accumulation raster from Hydro1k

I'm working with bioclim and hydro1k variables in ArcMap (10.2.2), ultimately with the goal of doing niche modeling. I've got all my h1k variables in their original formats (Lambert Azimuthal Equal ...
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1answer
690 views

Delineating large scale watershed?

I would like to do some watershed delineation at national/regional level (using SRTM-90 data). I have experimented with r.watershed (GRASS 6.4.3) but it fell over when I tried to do big stuff. I ...
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0answers
441 views

Determining inflow outflow of polygon based on flow accumulation?

I'm working with ArcGIS 10.2 to try to determine if a given site has some sort of outflow for the water coming into the site. I'm using the ArcHydro tools and have calculated the flow direction and ...