Questions tagged [catchment-area]

An area of influence defined by boundaries related to distance. In human geography, this area is defined as the location from which customers or visitors are attracted. In hydrology, this area defines the location within watershed boundaries (also known as a drainage basin).

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Why does running the SAGA Upslope Area tool in QGIS result in a 0 (zero) to 0 (zero) histogram and an all black layer?

I am using QGIS in order to delineate a watershed, and am using 1/3 arcsecond DEMs. I have created a Filled DEM using the SAGA Fill Sinks xxl (Wang & Liu) tool. Next I ran the SAGA Channels and ...
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PgRouting coverage area with node restrictions

I have a water network in which there exist valves at nodes between two edges (pipes). When the valve is open water can flow, if not, it can't. How can I calculate the catchment area from a start ...
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25 views

List of international upstream areas [duplicate]

I have a list of stations in rivers. I want Earth Engine to return me a list of stations whose upstream area overlaps with at least one other country in addition to the country the station is in. This ...
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Skipping undefined elements when getting catchment area

I have a follow-up question on Population in upstream area (looping over FeatureCollection). I want to calculate the number of people living in the upstream area of stations in rivers. This code works ...
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47 views

Population in upstream area (looping over FeatureCollection)

I want to calculate the sum of the population living in the upstream area of stations using the hydro package by gena. I think I will have to loop over the stations (using the identifier "GEMS_Stati")....
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91 views

Get catchment delineation with multiple outlets in QGIS 3.4 or 3.8

I'm starting with a DEM, then I generate a drainage direction layer (ldd). Then I'm trying to get all the watershed basins for multiple outlet points in a QGIS plugin I'm developing. I can get them ...
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217 views

SAGA: could not initialize data objects (QGIS 3.6, Mac 10.14)

I was trying to generate a catchment area from a DEM and got the error message: The following layers were not correctly generated.<ul><li>/var/folders/ft/rbsnpzy96r76t8rkj5fdtzc40000gn/T/...
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547 views

Watersheds and Catchment delineation in Earth Engine only with included datasets

Is there a possibility to derive Watershed boundaries or catchment areas by using one or more of the integrated data sets in google earth engine? The available data sets are: WWF HydroSHEDS ...
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73 views

GRASS Error: WARNING: segment zero_fill(): Unable to write (No space left on device)

I was trying to define the drainage patterns and to delineate some catchments based on a 30m DEM using r.watershed --overwrite elev=DEM accumulation=Accum drainage=Drainage -m but grass would ...
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How do I select rows in an attribute table of a vector layer grid which are outside of another vector layer?

So what I am working on is accessibility analysis, I want to know how many percent of the population of a country have access to certain health services within a given driving time. For example is it ...
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76 views

how can interior basins be modified in the r.watershed GRASS function?

This is a follow up question to How does "Minimum Size of Exterior Watershed Basin" work in r.watershed command in qgis 2.18.12? I understood that the threshold parameter is used to ...
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208 views

Hack's law for river basins

The hacks law relates the longest stream length with the catchment area of the basin. How can one construct a hack's distribution for a basin and upto what scale the sub basins have to be taken as ...
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Splitting catchments in GRASS

I have the polygon of my catchment of interest, I call it catchment A (Reyran in the schema). (format *.shp). I have also the x-y coordinate of a dam that is situated in the catchment. I have also a *...
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311 views

Saga Catchment Area not giving expected (useful) output

I am identifying a catchment network from a DEM in QGIS3 (v3.0.3) (on a mac v10.13.4), however the step to identify the Catchment Area is not working. I have an input DEM, with layer CRS set to ...
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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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108 views

Delineating service catchment in QGIS?

I have a set of locations each representing a service capacity. I also have a polygonal layer with each polygon representing local demand for that service. For each location, I would like to define ...
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1answer
89 views

pgr_drivingDistance How to split edge if max distance is reached halfway through the edge (PGROUTING)

I would like to generate a catchment within a network, up to a max cost, using the pgr_drivingDistance function. This returns all the nodes within this distance - but does not provide for partial ...
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529 views

Determining areas on a Voronoi Diagram around a point

I currently have two data sets concerning the Netherlands, one containing longitudes and latitudes of population cores (Hubs) along with other information, such as average house price, and the other ...
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1answer
64 views

How can one compute the proportion of a country's area that lies within a given distance from the country's border?

A lawyer friend of mine is preparing a legal argument that concerns the border region of Germany: the part of Germany that is within a given distance (e.g., 30 km) of the country's border. He needs ...
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1answer
57 views

Catchment area map automatic creation

I want to create a map that shows the catchment area of download mirrors. What I found so far is only a manual option where you have to draw an area around that point. But I don't know exactly where ...
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1answer
630 views

Error in catchment area calculation

I downloaded a DEM based on the ASTER Global Digital Elevation Model (resolution 30 m; ASTGTM2_N42W009_dem.tif) from the Earth Explorer website (https://earthexplorer.usgs.gov/). I am trying to ...
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Voronoi that don't cross boundaries

I have several dozen points plotted across the UK. Each point represents a facility that serves local people. To estimate the catchment areas of each facility I created Voronoi polygons around them, ...
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921 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 ...
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1answer
191 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 ...
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310 views

Combining several catchment areas

I would like to combine several catchment areas (points feature) into one catchment area. There are examples of my catchment areas. Each area has one source (POI).I will use the combined area to ...
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117 views

How to create a buffer for catchment area of an historical settlement

I'm looking for a way to create a buffer from a specific point that represents the catchment area in a selected time in QGIS. I've found many tools that allow me to do it using driving time or public ...
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1answer
4k views

Network analysis using QGIS?

I'm working on my bachelor thesis right now and I want to find a catchment area for different bus stops. Is there a function in QGIS where I could use a point layer as input, use ways as distances and ...
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1answer
8k views

Create a circle of defined radius around a point and then find the overlapping area on a shapefile

My use case is related to calculating the area of a polygon in a shapefile that is covered by another polygon. Specifically, I want to do the following: Create circles that have a 100m radius, from ...
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1answer
3k views

How to calculate areas of land cover from a File System Raster?

I am using ArcMap 10.2. I have a raster displaying land cover. I also have a shapefile of polygons overlaid on top. I would like to calculate the areas of different land covers within the polygons. ...
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121 views

Calculating weighted catchment area

I would like to calculate the catchment areas of several points in a polygon. It means, I have a city, some POIs in the city and a lot of districts (the centroids). The POIs have different weighting ...
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332 views

GRASS v.net.iso does not include all lines

I want to define catchment area for bus stops in small city. As a result of v.net.iso in QGIS with GRASS I don't get all highways in that city. Here are my steps: importing above layers into GRASS ...
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80 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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447 views

Multiple watershed delination with QGIS

I am trying to divide a DTM model in subbasins but I have set specific outlet points for the subbasins, and not to use a thershold. Is there a tool similar to r.water.outlet but with multiple outlet ...
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0answers
93 views

Can 2 GIS layers which representing the same area be compared directly while having the same datum but different coordinate system?

My question is about how coordinate systems affect comparison of different layers - I have tried to refresh my memory about coordinate systems in GIS, but am still unsure about this situation. I am ...
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21 views

Calculate how to cover an area by recepetion tovwers

I am working in a Nature Reserve and we are putting up towers that will be used to to track certain animal with collars on. The towers work on line of site only. We must place the towers in a matter ...
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1answer
123 views

Choosing projection for calculating 2D 3D area in New Zealand?

I'm trying to use Surface Volume tool in ArcMap to calculate 2D and 3D area of a catchment. What would be the best projection to use and how do i check the maximum error of the estimation?
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1answer
80 views

What's the syntax to skip optional saga:catchmentareaparallel parameters?

In PyQGis, I want to use saga:catchmentareaparallel algorithm, in the parameters there is an optional arguments, and I don't want to use them, what is the value should i put on the argument? i try to ...
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1answer
66 views

Does Scimap work with QGIS?

Does anybody know if Scimap ( http://www.scimap.org.uk ) works with QGIS? I know it is supposed to operate with ArcGIS and SAGA but as I am very much a beginner with QGIS I would like to know if its ...
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573 views

Catchment area calculation [closed]

I am trying to shortlist optimal physical locations in my county for developing recycling centres that serve the population. I have a vector point layer of the centre point of around 100 potential ...
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1answer
41 views

Seperate Intersected layers (as points)

I'm trying to establish watershed outlets as points with two shape files that I have available; i.The watersheds polygons ii. The river network As I said above I'm trying to define the outlets but ...
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58 views

Query processing time for network table creation using pgRouting 1.05

I am trying to follow these steps for creation of a network table using pgRouting 1.05. In my case I have two road geometry tables, one is bangalore_road and the other is all_india_roads. Obviously ...
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1answer
4k views

Edit existing polygons to include several new nodes

I want to define catchments which are quite large from vector contour data. I normally start zoomed out to define the catchment generally as it is easier to see. I then zoom in and refine the ...
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1answer
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Flow direction and catchment area polygons for utility water pipes

I'm working on a project where I need to show which direction the water would flow from a water pipe in case there is a pipe burst. I also need to show catchment polygons(area affected). This was ...
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513 views

QGIS 2.0 Catchment areas by using a 1 hour walking time

i would like to have catchment areas around my points which show the area of an one hour walk. I looked around and found information about using the hiking funktion for calculating a distance with the ...
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2answers
10k views

Creating catchment from point using DTM raster in QGIS? [closed]

I need to find a better way to delineate a catchment from a given point on a watercourse using a DTM - currently I am either using FEH, or if the catchment is too small using contours to draw manually....
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1answer
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catchment area using SAGA and Arcgis 10.2

I would like to calculate catchment area. I used D8 algorithm and running in both arcgis 10.2 and SAGA GIS 2.1.2. However, the results from two software are different. The lowest value of catchment ...
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177 views

Managing large number of catchments/watersheds?

Does anyone know of an easy way to manage a large number (10,000's) of catchments/watersheds? I have defined a stream network and for each segment, I have a corresponding catchment (in a unique ...
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1answer
918 views

Efficient algorithms for recovering watershed boundaries?

This is somewhat related to a previous question I asked: What Algorithm is used by ArcGIS Watershed tool? I was wondering if there is a more efficient way to calculate catchment areas if you are ...
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1answer
50 views

How to compute drive access to a station based on vehicle origin points? [closed]

I have a shapefile that contains station locations and another shapefile that is the geocoded origins of those who drove to the station. I would like to make a buffer around the station that shows the ...
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1answer
170 views

How to create a catchment area using LSOA and point file data [closed]

I have to create a catchment area (based on LSOA) for the 19 underground stations within Camden borough and it has to be in a polygon vector file. I know I have to somehow group the SOAs but don’t ...