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
32 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 ...
1
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0answers
24 views

How to load “soil types” in QGis?

I want to show soil transmissivity per pixel. Thus, I determine water holding capacity of each pixel (ignored other effective parameters). Respectively, I wonder, What is the soil data format and How ...
4
votes
1answer
95 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
49 views

Hydropower Calculation

I have assigned the elevation and the volume flow to each point at a river (with v.to.db and v.what.rast). Now I want to calculate the Elevation difference between each pair of points and then ...
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0answers
33 views

How to decide when flood started depending on the rainfall data?

I created a raster with the point values (mm) of rainfall data by interpolation in the raster menu. So I have a raster rainfall data and a DEM. With this rainfall data and a DEM corresponding to ...
1
vote
1answer
36 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 ...
3
votes
1answer
101 views

How to compute average slope and area-weighted average slope?

I am learning GIS for use in hydrologic analysis. Related to computation of overland flow there are two types of slope that I would like to be able to obtain from GIS. The first is average slope for ...
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0answers
32 views

Horton Stream Order as Category for r.fixed.segmetpoints with GRASS?

I'm working with Grass GIS. I want to use v.segment to set discrete, equidistant Streampoints (starting from each mouth). Since the water network is too large, it is impossible to define the rules ...
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3answers
67 views

Discrete Waterpoints with Grass

I've been working with Grass GIS for about two months. I have to develop a method for the identification of target regions of small hydropower plants. Boundary conditions are a predetermined minimum ...
2
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0answers
62 views

ArcGIS - Flow Direction (Algorithm)

I am curious about the algorithm of Flow Direction in ArcGIS. Recently I am studying about Hidrology, and I have some questions regard to Flow Direction in GIS. The size of this cell is 100m x 100m, ...
1
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0answers
48 views

How to do a flood simulation without flooding the whole area and covering surface structures (with DEM)?

I have a high resolution DEM and want to do a flood simulation starting at a river. My hope is that the water runs into historical (now dry) river channels (in which I'm interested in) at first and ...
7
votes
2answers
255 views

Find headwater polygons

This is a follow up question to this question. I have a river network (multiline) and some drainage polygons (see picture below). My goal is to select only the headwater polygons (green). With ...
2
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1answer
38 views

Is every cell in flowdirection draining towards an outlet

I have created a Flowdirection map in a defined catchment. I want to find out if every cell in my map is flowing towards the creek/outlet. Is there an easy way to do this? I have created the ...
3
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0answers
70 views

Extract representative slope profiles from hillslope polygons

With the help of the Whitebox Geospatial Analysis Tools I was able to easily extract hillslopes from a river network in combination with a flow direction map. Now I would like to extract ...
2
votes
1answer
41 views

Delination of half basins or hillslopes from a flow direction map or/and a stream network

I am using the GrassGIS r.stream.extract extension to delineate a stream network with the options 'mexp' (Montgomery exponent) and 'd8cut' (Use SFD above this threshold). It works perfect so far and ...
2
votes
2answers
73 views

Merge layers and fill gaps

I have 14 layers, which are polygons. They represent the channel of a river at different periods. I need to fill the gaps that exist once I overlay the polygons, but I can't change the properties of ...
1
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3answers
87 views

why Input layers do not have the same grid extent in the processing, hydrological analysis?

I'm trying to generate the hydrological analysis using processing and I have already done some terrain processing using the DEM. In this moment, I'm working in he channel network but, when i assign ...
0
votes
1answer
76 views

Urban Hydrology Using With GIS

I'm researching how can I create a model urban floodplain depending on rainfall. And Which programme should I use? I want to show floodplain depending on temporal and spatial distribution on study ...
2
votes
1answer
64 views

Water feature growth

I have a water feature layer which includes rivers, lakes and streams. I want to create, essentially, a buffer of these features equal to that of a 50cm increase in elevation from its current ...
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0answers
129 views

QGIS SAGA Channel network error: Input layers do not have the same grid extent

I am trying to follow along with this exercise using my own DEM. I have done the first step, creating the catchment area, with no trouble. When I try to run the Channel network algorithm, however, I ...
1
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0answers
41 views

create a weight raster for a hydrology analysis

I determine affecting parameters of flood flow ( evaporation,vegetation,soil type, rainfall etc.). Then, I start to analysis using Arc Hydro. How do I relate among of affecting parameters? How can ...
0
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2answers
45 views

Are there publicly avaiable run-off data for Africa

I was wondering if there are good publicly available dataset for surface run-off (water)? I have a rough idea that surface run-off should be some function of rain-fall and soil ...
1
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0answers
23 views

Interpreting some hydrology data

This is the historical feed of the Keystone dam for October 2014: http://www.swt-wc.usace.army.mil/chartbin/KEYSOct14.shtml Here is the real time feed: ...
1
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2answers
47 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 ...
3
votes
1answer
64 views

To make a map of sinkholes on grass gis

I would like to make a map of sinkholes. I have a DTM ARC/INFO ASCII GRID of Asiago Plateau and and I'm using grass gis. Does anyone know what is the correct form in grass gis?
2
votes
2answers
74 views

ArcGIS are two rasters the same? - including null values

I am working on a task to calculate Height Above Nearest Drainage (HAND) - that is the height above the nearest point along the flow path that is on a drainage - not the geographically nearest ...
2
votes
1answer
60 views

Aggregating river basins

I am not a hydrologist but am providing GIS infrastructure to our hydrology department which actually doesn't use GIS very much yet. Therefore I am asking for some hydrology related insights. Btw: We ...
3
votes
1answer
126 views

Horton Stream Ordering in ArcGIS?

Is there a way to order streams using the Horton (opposed to Horton-Strahler) method in ArcGIS (10.2.2)? I know the Stream Order tool allows you to use Strahler and Shreve.
0
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0answers
10 views

Difference of Archydro and Hydrology Between [duplicate]

What are differences between archydro and hydrology tools? What does ArcHydro add on hydrology tools?
11
votes
2answers
1k views

How to cartographically represent water flow?

I am modelling water flow on steep slopes for an erosion study. You can see from the screenshot the results from the ArcGIS-based flow analysis. To produce these flow lines, I generated a ...
5
votes
2answers
154 views

Is there hydrologically correct water-course data for Africa

I was wondering if there are any hydrologically correct river-channel data available for download for Africa? By hydrologically correct, I mean the topology should be correct. Connected river ...
1
vote
1answer
290 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 ...
3
votes
1answer
132 views

Practical tools to delineate 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 ...
4
votes
2answers
178 views

Calculating flowpaths downstream of a point

I am assessing the flood risk posed by pipeline failure. I need to calculate the likely flow-paths for flood water downstream of critical locations along the pipeline using GIS. I'm familiar with ...
3
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0answers
54 views

Where to find comprehensive descriptions of tools in QGIS, SAGA, Orfeo, etc. toolboxes? [closed]

There exists a large number of tools for QGIS (e.g. SAGA, GRASS, ORFEO etc.) - however none of these have sound description of the aim of the tool, the algorithm itself, differences to other similar ...
3
votes
0answers
273 views

Extracting flow accumulation to stream shapefile

I would like to create a shapefile that displays the flow accumulation for a given point in a stream channel. Is this possible? My client wants a map that shows the accumulated flow/catchment area ...
1
vote
1answer
137 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 ...
1
vote
1answer
128 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 ...
0
votes
1answer
273 views

D8 algorithm to get the flow direction in ArcGIS

I am using ArcGIS 10 for the get the flow direction from DEM. I wonder about the algorithm they have used while calculating flow direction. It is mentioned there that it is using D8 model. D8 model ...
1
vote
1answer
67 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 ...
1
vote
1answer
238 views

Creating weight raster for flow accumulation in ArcGIS for Desktop?

I am studying flood flow using ArcGIS for Desktop. When creating flow accumulation in hydrology, there is a weight raster. However, İf you do not have it, the programme sets its value to 1 which is ...
4
votes
1answer
324 views

Generate channel network (rainwater run off) - which algorithm is the best?

I want to compute DEM for a whole country (cca 79 000 sqr. km) and I need to be hydrologically correct as much is possible. After, for this correct DEM I need to compute drainage lines of surface ...
1
vote
0answers
65 views

Determining uppermost point in stream based on gradients?

I am trying something new and was hoping someone out there may have done this same process or something similar or may have a best approach. For this particular project I am working with ArcMap ...
0
votes
0answers
118 views

ArcGIS ModelBuilder Clip Raster by Polygon Error

My task is to derive the hypsometric integral and hypsometric curve for a lot of drainage basins. Since it is very time consuming to do this manually, i have created a model (with help from this ...
1
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0answers
122 views

r.stream.* commands do not work in qgis environment

I have been working for a while with some grass commands in QGIS environment (r.watershed, r.terraflow, r.thin, r.to.vect etc) with out any problem. I haven't been able to get any results at all from ...
4
votes
0answers
156 views

Flow direction generated for river is incorrect

I am trying to generate a hydrologic model and I can not really proceed on the next processes. I have this problem on generating flow direction. I have already executed fill sinks and the next is flow ...
2
votes
1answer
275 views

Negative Topographic Index Values

I am getting negative topographic index wetness values in SAGA GIS - anyone else every get this? Not all negative values, but the minimum of the TWI range is negative for some steep watersheds we are ...
0
votes
2answers
157 views

r.topidx error: required parameter output not set

I'm calling GRASS r.topidx from QGIS 2.2.0. I can get other tools to work on the DTM, for example r.watershed. But r.topidx I get the Oops message: Oooops! The following output layers could not be ...
1
vote
2answers
64 views

Divide stream segment at specific point

I have a stream network and outlets as shown below. It is overlapped with outlet cells raster which I can use to get sub-watersheds but when I add an outlet (red color cell in current example) then ...
5
votes
4answers
394 views

What satellite imagery would help to show spring locations?

I've got lots of tiny streams on a hydrography shapefile. Historic texts indicate that certain ones have headwaters at "sources" or springs, and I want to try to find these. Browsing the historical ...