Questions tagged [hydrology]

The study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability.

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2
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1answer
292 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 ...
0
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0answers
499 views

Preparing SRTM (hgt) for use in SAGA GIS?

I am trying to prepare a raster file which i could use with SAGA processing tools for hydrologic analysis in QGIS. I am using Win 7, 32 bit, QGIS 2.14.20 and SAGA 2.3.2 I downloaded the srtm file in ...
4
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1answer
129 views

Limiting flow direction to D4 instead of using D8 in ArcMap?

Is there a way that I can limit flow direction to D4 instead of having it use D8? Preferably looking for a way to do it within ArcMap.
1
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2answers
177 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 ...
2
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1answer
280 views

Which algorithm is used for fill sinks in arc hydro tools?

How I can get information regarding the % of voids filled using fill sinks in DEM and the algorithm used to fill the voids using arc hydro tools?
1
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1answer
203 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 ...
0
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1answer
128 views

Find the nearest point on a stream network from a given point?

I have a vector layer for stream network created by r.stream.extract and then vectorized stream file using r.to.vect of grass algorithm in qgis. I want to find nearest point for a given point on ...
1
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1answer
92 views

Stream order from flow accumulation raster

I am looking to get Strahler Stream Order vector from a flow accumulation raster of a river network. I only find solutions with an elevation or direction raster. Can I do this with GRASS?
-4
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1answer
455 views

Fill DEM with water [closed]

I want view how a volume of water calculated with Hydrologic Study, accumulates in lower parts of my DEM at 1 meter resolution. My goal it's view the level that water reaches inside the raster. It's ...
6
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1answer
501 views

Delineating coastal subbasins using SAGA GIS or GRASS in QGIS?

I'm having some problems trying to delineate watersheds using the SAGA watershed delineation tools in QGIS. I have a SRTM DEM (cell size 30 m) which I set the water cells to NULL values, following ...
1
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2answers
954 views

Longest Flow Path in QGis

From a DEM of a watershed, how is possible to calculate the longest flow path? I know this questions has been asked before but I haven't found a complete solution yet.
1
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0answers
36 views

Production of DEM on ArcMap from LiDAR data? [duplicate]

I am trying to produce a DEM for my dissertation (i'm relatively new to ArcGIS) so that I can conduct hydrological analyses of catchments. I have downloaded LIDAR (.laz 2x2 km) data and have created a ...
3
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1answer
771 views

QGIS: Saga Channel network: how to prepare SRTM data

I am trying to use the Saga toolbox (2.2.3) in QGIS (2.18) to create a channel network from SRTM data using this tutorial 1. It works, but the result I get when using the DEM that comes with the ...
2
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1answer
156 views

GRASS r.basin resolution error at strahler stage

I built a composite DEM of Florida using USGS NED 1 30m DEM tiles. I used r.patch to convert the individual tiles into a single raster and then projected it into a new region with the EPSG:26958 ...
4
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2answers
816 views

Generate Height Above the Nearest Drainage (HAND) using QGIS

I have a DEM I want to generate a HAND for and want to do so in QGIS. Does anyone know of any plugins or the processing steps to be able to do this?
3
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1answer
205 views

Selecting contour lines with higher elevations on either side

I want to select contour lines that have lower elevation values from neighboring contour lines. I'm using ArcGIS but do not have the hydrology tool set. I can use open source if needed. I thought ...
1
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2answers
49 views

Where water will be on a mudflat as tide comes in/goes out?

My study area is large intertidal mudflat in NE England. I want know where the water will be depending on tide height. The attached shows an aerial of my study area. I've photoshopped in the blue ...
4
votes
1answer
319 views

Lowering density of GRASS r.stream.extract result?

I am fiddling with the GRASS plugin in QGIS to produce watersheds and drainage basins as well as being able to identify all the basins and watersheds leading to one point (depending where i chose to ...
4
votes
1answer
257 views

Obtaining length of river upstream of points up to next point using ArcGIS Desktop?

I am carrying out a study which aim is to come up with a list of priority obstacles to fish migration to be removed based on those where more extra habitat would be created after the modification. I ...
1
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0answers
89 views

Adding curb/gutter and subsurface storm drain networks to watershed analysis in QGIS

I need to do a neighborhood scale drainage analysis. The analysis needs to accurately show the drainage area to each storm drain inlet. Using GRASS on QGIS 2.12.1 on OS X, I have been able to ...
1
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1answer
109 views

Delimit Hydrographic Basin, based on a single river

I find myself doing a hydrological study, where I have to delimit the river basin based on a single river (polyline). I have the DEM where the river of my interest is, and I have the river as a ...
4
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1answer
57 views

Assigning accumulating numbers to events along a (river)network

I have a river network along which there are lake polygons that I want to assign orders to. So from headwaters to downstream I want the order to increase depending on the number of previous lakes. As ...
-1
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1answer
301 views

Cumulative delay function for rainfall-runoff modeling using TOPMODEL [closed]

I am trying to model rainfall-runoff using TOPMODEL in R. The TOPMODEL needs an input called "cumulative delay function". The R documentation says "Flow is routed through a delay function which ...
5
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2answers
2k 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:...
1
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2answers
509 views

Calculating Stream gradient in ModelBuilder - Shapefile iteration?

I'm working on some project (in ModelBuilder) and of its element is calculating stream gradient. I have shapefile with rivers, each segment have specific length. I want to calculate stream gradient ...
1
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1answer
29 views

Preserving uniqueness for overlapping points when converting from points to raster?

I'm trying to optimize outflow points based on lowest elevation within some tolerance. Using the SnapPourPoint function which does exactly this, but outputs a raster file. I've been converting this ...
2
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0answers
41 views

Deleting duplicate values (depending on second condition) from raster attribute table? [closed]

How can I automaticly delete rows from a raster attribute table if the value of a specific column appears twice or more? For example my attribute table (below) shows in the column "Streamlink" the ...
2
votes
1answer
423 views

SAGA Upslope Area Calculation from Vector Point Layer resolves in no output and no error message

I'm using the SAGA Upslope Area algorithm within pyqgis, but i'm stranded, since my script doesn't create any output at all. I'm trying to use geometry from points in a vector point layer as input x ...
1
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1answer
212 views

Burning an open channel in DEM

I need to burn a DEM surface to generate an open channel. (all dimensions and slopes are known) I thought I should use raster calculator to subtract a raster represent channel depths from the DEM ...
1
vote
2answers
141 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 ...
1
vote
1answer
371 views

Calculating mean altitude of watershed for each cell of DEM?

I have a DEM of river basin, and I need to create a raster where the cell value will be the mean elevation of watershed of this cell. I have calculated watershed area (flow accumulation x cell area). ...
0
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2answers
170 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 ...
3
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1answer
79 views

Creating a shapefile with accumulated discharges in ArcMap 10.2

I have a shapefile which represents a waterbody (first picture) and I have a point shapefile which shows the location of discharges (second picture). Is it possible to create from these datas a ...
1
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1answer
42 views

Calculating flowaccumulation in specific areas

I there a way of calculating only the flowaccumulation which are generated in the yellow area and assigning this calculated value to the related end of the stream which is entering the river? red ...
2
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0answers
72 views

Choosing diffusion coefficient and other parameters for r.sim.water in GRASS7?

I'm trying to run r.sim.water in GRASS7 to simulate overland flow during a heavy rain event. My DEM has a resolution of 1m. I prepared it by adding values for buildings and included ditches and ...
0
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1answer
150 views

Flow Accumulation Stream Buffer

I would like to create a dynamic buffer based on contributing drainage area for a stream. I have done some research and I think the best way would be to use the flow accumulation tool but I'm not sure ...
2
votes
1answer
75 views

What Algorithms to use for Levee breach Analysis?

I have a (relatively) High resolution DSM of the Country side, and want to figure out the extent of area that will be flooded if the Embankment/levee fails at a a given point. Something like this: ...
1
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0answers
146 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 ...
0
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1answer
152 views

r.fill.dir blocked

I am trying to fille a DEM downloaded by Geobolivia http://geo.gob.bo/. The r.fill.dir module in QGIS/GRASS toolbox blocked few minutes after I launched it for the DEM. It is very strange as, for ...
1
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1answer
808 views

How to Create a Catchment Area of a Polygon (Wetland) using DEM in QGIS or Whitebox GAT

I am looking for a way to calculate the upstream catchment area where water would flow into a given wetland. I have delineated the boundary of a wetland (creating a polygon) and would like to ...
1
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0answers
66 views

Deriving Stream-Velocity out of a DEM

I'm using Arc GIS Toolbox Hydrology...everything works fine. Moreover, it is possible to derive the potential stream velocity just out of the DEM? Informations about rainfall, infiltration, hydraulic ...
1
vote
2answers
253 views

Select neighboring cells from a raster under conditions

I generated river networks (raster format) from a DEM and I also want to select the neighboring cells of the river networks from the original DEM, if the neighboring cells have a lower or equal ...
2
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0answers
78 views

Comparing areas of two raster files [closed]

I need to compare the areas of two rasters for calculating the percentage parts from another. For example, I have one raster file which shows separated agriculture fields. The value of each field is 1 ...
3
votes
1answer
2k views

Extract river polygons from DEM

I would like to use DEM to extract a river network but I don't want to use the polylines. Is it possible for me to extract polygon (or raster) rivers from DEM? I'm using both ArcGIS 10 and R. If ...
0
votes
1answer
1k views

Explanation of HAND (height above nearest drainage) model procedure

i tried to follow this procedure Spatial Analysis - Calculate a cells elevation (height) above the nearest stream cell but i have some problem to understand everything. I mean the 2th answer in the ...
3
votes
1answer
453 views

Negative values in r.watershed flow accumulation

I am trying to process a DTM by using r.watershed in QGIS 2.14.3, with the GRASS GIS toolbox. It should be the file named: "Number of cells that drain through each cell". I get some negative values, ...
1
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0answers
134 views

Getting distance from nearest stream and elevation to nearest stream?

I need to know if there are simple commands for this 2 points: the distance from the nearest stream, D [m], defined as the length of the path that hydrologically connects the location under exam to ...
5
votes
1answer
286 views

HEC GeoHMS generates wrong catchment area

I am trying to define a catchment area automatically with HEC Geo HMS (ArcGIS version 10.1). My input-data is a DEM-file (raster 1m). After doing all steps in HEC Geo HMS, the catchment area (see ...
0
votes
1answer
121 views

How to calculate stream order in GRASS 7.0.2?

I would like to calculate Strahler's and other stream hierarchy from my input raster but I am not sure how. This manual suggests tat I should use r.stream.order command, however in version 7.0.2 "...
6
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1answer
746 views

In hydrologic terrain analysis is there a difference between “pits”, “depressions”, and “sinks”?

In hydrologic terrain analysis is there a difference between "pits" and "depressions"? For instance, Planchon and Darboux (2002) state The usual numerical methods for removing the depressions of a ...