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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2answers
654 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 ...
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1answer
32 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 ...
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0answers
42 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 ...
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1answer
487 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 ...
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1answer
246 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 ...
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2answers
169 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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1answer
461 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). ...
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2answers
211 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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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 ...
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1answer
43 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 ...
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0answers
104 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 ...
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1answer
172 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 ...
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1answer
82 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: ...
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0answers
155 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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1answer
251 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 ...
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1answer
962 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 ...
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0answers
68 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 ...
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2answers
307 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 ...
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0answers
81 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 ...
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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 ...
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1answer
2k 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
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1answer
612 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, ...
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0answers
141 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 ...
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1answer
329 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 ...
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1answer
179 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 "...
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1answer
809 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 ...
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2answers
269 views

How to calculate shortest distance from start to end of river?

How can I calculate the straight distance from the start to the end point of a river (red line in image)? I don't know how to do this automatically.
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1answer
327 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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1answer
146 views

Create a flow network from a flow direction ARC GIS

First, I created a flow_direction from a DEM, then I applied corrections to this flow direction. Now my question, how to create a flow network (order flow) from a flow direction, that I already ...
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1answer
421 views

Constructing LS factor for RUSLE without outliers using ArcGIS for Desktop?

I'm using the following formula in RUSLE via raster calculator to obtain a LS factor Power(Flowacc)*1/22.1,.4)*Power(sin(slope)*.01745/.09,1.4)*1.4 My expected outcome is a raster from 0 to ...
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1answer
303 views

Curve Number equation in ArcGIS Raster Calculator?

I have a floating point raster of Curve Numbers (70-91) and I'm attempting to use the curve number equation to create a weight raster for flow accumulation, to determine runoff for a single rainfall ...
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1answer
2k views

How to create an elevation profile in google earth from a kml?

I have a KML file of a stream that I originally created as a line shapefile in ArcMap (one stream extracted from a larger watershed data set). I need to create an elevation profile of this stream. ...
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1answer
5k views

Downloading Hec-GeoHMS for ArcGIS 10.3.1?

I can't download geohms from this link http://www.hec.usace.army.mil/software/hec-geohms/. Can anyone help me to get Hec-GeoHMS for ArcGIS 10.3.1? The doesnot responds and I could not get a Hec-...
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1answer
710 views

Issue with r.watershed run by QGIS-Python-processing.runalg

I would like to extract flow accumulation and flow direction layers from a DEM calling the grass r.watershed module from a QGIS-python script using the processing class. I obtain just an empty map, ...
2
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1answer
127 views

Cost Path based on Lowest Maximum Elevation Encountered

I am trying to locate the lowest elevation point at which a river will overtop its banks, and spill into lower-lying terrain behind them. I'm working in ArcMap version 10.2, and using a high-...
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3answers
3k views

Calculating average stream slope at each location along stream using ArcGIS Desktop?

I'm trying to calculate the time of concentration for every point along a stream network. To calculate the time of concentration, I need the upstream channel length and channel slope. I've been able ...
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1answer
480 views

Using the watershed tool with two pour points

I have two pour points in a stream network created using the flow accumulation methodology in ArcMap. When I use the watershed tool with this pour point shapefile, I get a watershed between these two ...
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1answer
64 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
73 views

Dividing stream network of specified lengths in ArcGIS for Desktop? [closed]

we are trying to find hydro power potential of river basin by using ArcGis and SWAT ,we have created stream network ,but unable to divide stream network at 500mts interval, unable to find the tool
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1answer
1k views

Hydrological model building for flooding analysis [closed]

I am recently studying the topic in investigating the features of river and to perform flooding analysis. I got the elevation data, and I used the elevation data to generate streams in ArcGIS and I ...
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1answer
864 views

Calculating watershed using snap pour points?

I am trying to calculate a watershed layer and have followed instructions from this previous question: General steps to create watershed boundary in ArcGIS Spatial Analyst? I have combined all these ...
3
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1answer
309 views

How to delete obstacles (corduroy road) from DEM in ArcMap?

I have a DEM which looks like this: The narrow longish lift running from north to south is a corduroy road (hope this is the correct word for "planks which allow people to cross a mire without ...
4
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1answer
1k views

How is “Burn Stream Slope” in ArcHydro working?

I have a DEM with only small relief and many ditches. Because of the small relief, I can't calculate flowdirections for some parts of my DEM. I know that in reality water is flowing from west to east (...
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1answer
3k views

Calculating Flooded area / Inundation in ArcGIS for Desktop?

I was tasked to create a layer with the flooded areas if the sea / river level was to go up by X feet. There is no requirement to take Flow and Pour Points into account, just a simple raise in water ...
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2answers
167 views

How to plan preservation of wetland using a DEM and ArcMap?

I'm trying to plan a wetland preservation. This is the DEM I have: My aim is to hold as much rainwater as possible in my area of interest (red poly) by building (as few as possible) new and raising ...
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2answers
813 views

Get upstream sections of a network

Is there any extension to get all upstream sections of a polyline shapefile which represent an hydrographic network in QGIS? It could work like this: you choose a specific branch and a direction ...
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0answers
454 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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2answers
918 views

Correcting Errors in Height Above Nearest Drainage (HAND) model

I have used this tread Spatial Analysis - Calculate a cells elevation (height) above the nearest stream cell to create a HAND map in ArcGIS. First I used the hydrology toolset to fill in sink in the ...
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0answers
322 views

Measuring river width every mile in Google Earth?

Given an area, can Google Earth tabulate the width of a particular river? This problem I think requires using an API to programmatically: define an area of interest identify a terrain feature like ...
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0answers
46 views

How to join hydrological data from a big area with a small area with better pixel resolution?

I use TAUDEM to make hydrologic analysis. I have a hidro 1K dem file from South America (big area) pixel resolution=1000x1000 meters. I have a specific dem file located in Brazil (small area) pixel ...