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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6k views

How to determine drainage area upstream from point?

I do not know how to come up with the drainage area (km squared) upstream of Lat 77.84, Long -30.96. I have converted my contour shapefile to a raster, identified and filled the sinks and then created ...
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2k 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.
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174 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
607 views

Conversion of diagonally adjacent pixels into one polygon?

I am trying to vectorize a raster whose digital numbers indicate different classes they belong to. ArcGIS and QGIS yield similar results: separate shapes out of pixels sharing the class that are ...
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1answer
101 views

TauDEM Model Availability

I'm trying to find the TauDEM Model Builder Models toolbox. I'm teaching myself how to use TauDEM to delineate watersheds. After running through some examples I started putting the modules together ...
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2answers
190 views

Interpreting GLDAS 2.1 precipitation data

I am trying to use the GLDAS 2.1 3-hourly precipitation datasets available at: The dataset is documented here: https://hydro1.gesdisc.eosdis.nasa.gov/data/GLDAS/README_GLDAS2.pdf The data is ...
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1answer
183 views

Hydrological conditioning using stream vector in GRASS?

I would like to make an hydrological conditioning of a DEM using an available stream network in vector form. I know r.hydrodem but it doesn't allow to use the stream vector. I need something to burn ...
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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 ...
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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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1answer
880 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 ...
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1answer
2k views

How to derive stream order from vector network [duplicate]

I have a recently-updated extract from NHD High Resolution (updated in last 6 months) which means it hasn't been cranked through NHDPlus, and won't for many years to come, and thus has no Stream Order ...
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501 views

Tool in ArcGIS for stream flow analysis?

I'm just wondering if there is any tool in ArcGIS that can be used to analyse stream flow measurements. For example, estimating runoff, baseflow and baseflow index based on stream flow measurements.
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1answer
306 views

How to estimate flow paths between contaminant sources and catchment offtake (exposure point) at catchment?

I am trying to estimate flow paths between contaminant sources and the catchment offtake (exposure point) at the catchment. Can anybody give me some help in how to proceed?
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162 views

viewshed analysis for observers wearing visors?

I'm starting with a DEM, and looking to identify every point that can be directly "seen" from any point in a particular polygon on an overlaid layer defining an area on that DEM - like any other ...
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1answer
63 views

GEE: masking for multiple pixel values

The GEE tutorial shows how to mask an image for one pixel value using .eq(pixel value). However, I want to mask all pixels in an image with a value of 15 or less in this dataset var riverflow = ee....
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1answer
73 views

Changing lakebed symbology to relative depth in ArcGIS 10.5 (TIN or raster file)

I have several TIN files representing empty lakebeds at altitudes ranging from 5000m to 3000m. I have calculated the TINs using ArcGIS hydrology tools and an ASTER v3 DEM projected to ...
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2answers
344 views

Define catchment boundaries with GIS using R

Using a DEM, I want to define catchment boundaries for a given location on a river. Basically, what area drains into this point. In ArcMap, I can do that with flowacc and other tools; but I'd like to ...
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1answer
117 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?
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2answers
679 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
468 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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1answer
987 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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2answers
317 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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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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2answers
937 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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4answers
552 views

Mapping UK river gauges / stations

Do you know a way to map all the river gauges / stations in UK? I found some data from the Environment Agency but it lacks of the longitude and latitude.
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1answer
3k views

How to calculate the river slope for a lot of rivers automatically in ArcMap?

I'm working with ArcMap 10.2 and I'm pretty new in this area.. What I want to do is compute the river slope for a lot of rivers from a DTM...I know that there is a way to do it manually passing by ...
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1answer
1k views

Using rainfall data (raster) as an input to determine stream lines in Arc Hydro?

I was wondering if it is possible to use rainfall data (raster) as an input to Arc Hydro for determining stream lines? I am learning Arc Hydo and have gone through a couple of tutorials. As far as I ...
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1answer
57 views

How to automate flooded area calculation and make report using PyQgis?

I have 3 shapefiles with me. They are a flooded layer, District layer and Village layer. To estimate flooding village wise, I have to do intersecting the features and get the layer. Then I calculate ...
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1answer
57 views

Using GageWatershed Function in TauDEM?

I have a D8 flow direction raster made from with TauDEM's D8FlowDir method and a point vector with an attribute 'id' for each. For some reason when I use these two as input in the GageWatershed ...
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2answers
55 views

Acquire direction between points along route

How can I generate a directionality attribute between two points along a route/line? Currently I am using Network Analyst to determine closest facilities, but I need a direction (upstream/downstream) ...
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2answers
197 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
268 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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1answer
128 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 ...
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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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1answer
251 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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1answer
336 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
150 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
499 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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1answer
965 views

Watersheds tool does not create watersheds in ArcMap?

I`m trying to create watersheds and every time I run the Watershed tool, the result will be very interesting. I use snap raster and I set the extent of the output to the extent of the flow direction ...
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1answer
855 views

Calculate River Runoff Volume (Q) with GRASS

I want to calculate Hydropower between points at a River. I already created a Rivernetwork and the Accumulationmap (without weighting) with r.watershed. My next Step was to set equivalent points along ...
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2answers
133 views

Where can I find hydroelectric generation data for the U.S.?

It is my understanding that the US Army Corps of Engineers has some hydro generation data on their various websites (divisions, districts). For example, there is real-time hydro-electric data ...
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1answer
201 views

Flow accumulation raster loading in QGIS 2.4.0 with null values (but flow direction loading ok!)

I have been tasked with creating an open-source hydrology dataset for a community group. To do this I have exported the flow direction and flow accumulation rasters from ArcMap as TIFF files and then ...
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1answer
4k views

How to indicate flow of a watershed feature?

While tracing and digitizing rivers, streams, rivulets, etc., is it possible to indicate the direction/flow in the shapefile on QGIS? I'd like to avoid using map labels. Ideally, when done tracing, I ...
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1answer
661 views

How to use ArcMap for HydroPower Potential

I am trying to determine the sites for small hydropower. I have a elevation dem, rainfall data, Curve number data (from soil and landuse shapefiles). I have already used the DEM to fill sinks, find ...
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1answer
3k views

Calculating longest flow path and avg. slopes for catchments with qgis?

I am a hydrologist and there are 2 important pieces of information I need for modeling. I need to know the longest flow path for each sub catchment in my area of interest and I need to know the ...
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1answer
142 views

About Interpolation Method using GIS10?

I have attached my stream network where the green dots shows the location with discharge gage now I want to create a raster all along the stream network to have a discharge data all along the river. ...
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1answer
217 views

Determining Pixel-by-pixel Catchments in ArcHydro

I used ArcHYDRO to prepare HydroDEM (5m) without sinks, Flow direction (FDR) raster, flow accumulation raster (FAC). As I understand FAC, value of pixel shows number of pixels that contribute to this ...
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1answer
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TauDEM fails to create stream network shapefile (-net option) when running StreamNet method on Ubuntu

When I try running TauDEM's "StreamNet" method including the optional -net flag to create the stream links / channel network as a shapefile, it fails with a lot of errors like: ERROR 10: ...
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0answers
41 views

How to interpret the Maximum flow path length raster, from the SAGA Maximum flow path length tool

Does anyone know how to interpret the Maximum flow path length raster, after running the SAGA Maximum flow path length tool? I have used this tool and received a raster but I'm not sure how I can get ...