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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18
votes
2answers
1k views

Proper workflow for LAS to DEM conversion

I regularly come across LiDAR (.LAS) files with elevation data. When I do, I always struggle to find a way of converting them to a DEM for hydrological analysis. I have developed several workflows, ...
13
votes
6answers
6k views

Methodology for creating accurate drainage networks (and catchments) from high resolution LiDAR DEM?

This is not the first time I've stumbled over this issue; it seems that I am unable to generate a correct drainage network model and the resulting catchments from full resolution (1m cells) LiDAR ...
10
votes
2answers
163 views

Account for bridge overpasses in a ground DEM to allow for water flow under the overpass

I have a bare earth DEM made from lidar data (A). It works well and has passed all accuracy tests. It is used in storm surge models. The problem we are having is on underpasses. I need to allow water ...
9
votes
4answers
4k views

Tutorial on how to model flooding using data from gauging stations along rivers in QGIS?

Can someone please direct me to a tutorial where I can learn more about how to model flooding using data from gauging stations along rivers using QGIS?
9
votes
4answers
460 views

What Algorithm is used by ArcGIS Watershed tool?

Does anyone know what type of algorithm is used in the ArcGIS Watershed tool (in the Spatial Analyst package)? Very little information given on Esri's website ... but I suspect it may be some kind of ...
9
votes
1answer
173 views

How to create a branch network from several input points to an unique outlet in minimizing the distances?

I am searching a way to "hydrologically" connect upstream points to a unique downstream outlet by creating an optimized stream network as pictured below... The cummulated lenght of the stream lines ...
9
votes
2answers
904 views

How can I get weighted Flow Accumulation to deal with negative values? [duplicate]

here's one I haven't seen anywhere, to my surprise. I am trying to do something a little different with Flow Accumulation, which I would think has been attempted before, but it's stumping me for now. ...
6
votes
1answer
2k views

Calculate Topographic wetness index in SAGA

i am currently working on a project which involves the quantification of the wetness in certain areas. However it produces quite different results from what i expected. I'll describe the steps i have ...
6
votes
2answers
2k views

How to determine elevation drop along a stream with ArcGIS?

I need to calculate(estimate) hydraulic head(elevation drop) along a single river stream in order to find potential site for small hydropower plant. I have a DEM with 20m resolution and raster and ...
5
votes
4answers
371 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 ...
5
votes
1answer
97 views

How to assign correct flow direction to stream network polylines?

I would like to create a map showing the results of watershed analysis as well as the resulting stream network with flow direction. I have a stream network which has been created from the flow ...
5
votes
3answers
422 views

Tracing up a stream network & tabulating attributes of polygons it passes through

I have an ArcGIS question that is either very easy or impossible (my favorite kind). I am somewhat inexperienced when it comes to dealing with network analysis, so maybe I'm missing something major ...
5
votes
1answer
2k views

How to calculate stream order for vector data without a DEM?

I have a shapefile which contains the streams that were digitized from a satellite Image. I would like to calculate the stream order for this data. The data does not exactly match the DEM that I have, ...
5
votes
1answer
321 views

How do I get the upstream distance to all points in a DEM from a single downstream point?

I want to get the upstream distance to all points in a DEM from a single downstream point. The goal is to create a "downstream distance to a point grid". This then would allow me to create "distance" ...
5
votes
1answer
86 views

Global Basin Delineation Across Dateline

I'm trying to delineate all river basins on a global 1/16 degree grid. The algorithm that the Basin tool in the Spatial Analyst Toolbox works well (fast) except it doesn't know how to handle the ...
4
votes
1answer
309 views

Which flow routing algorithms does ArcGis support?

Other than standard D8 are there support for multiple flow algorithms like FD8, DEMON, Dinfinity etc?
4
votes
5answers
920 views

Calculating Runoff / Streams using DEM in ArcGIS

I am just curious about the workflow that many of you use for runoff/stream analysis using a DEM and create a "water network" from the results in ArcGIS 10.1? I know the average rainfall for different ...
4
votes
1answer
728 views

Assigning points to their respective Reaches using Stream Gradient?

This is a continuation of the question I initially posed here. Also, I've attached a shapefile on my Drop Box account here. I'm trying to break a stream network up into 100m reaches, assigning ...
4
votes
1answer
154 views

Hydrology toolbox versus ArcHydro toolbox

I would like to do some watershed delineation research/development (at the County level) with our LIDAR generated DEM, after it is corrected, but am wondering what, if any, differences might result ...
4
votes
2answers
141 views

Hydrology, operational rainfall-runoff models

I am trying to collect information about operational rainfall-runoff models used around the world. I hope to build database with country outline with attached information what organization is covering ...
4
votes
1answer
96 views

Is there a downloadable data source for mapping out rivers with names for the whole world?

I'd like to be able to extract rivers with their names and the flow size (not direction) for the whole world. The scale I'll be drawing it at is about 2 centimeters per 10 real world km - nothing too ...
4
votes
2answers
348 views

Find locations of raster maximum within polygons: Basin Delineation

I'm trying to identify the Location (lat/lon) and upstream area of every raster point that flows into the Arctic Ocean (there are a lot so it has to be fully automated). I'm starting with the ...
4
votes
0answers
258 views

Proper use of Modulus “%” operator in ArcMap [closed]

Objective: Gather pour points to define a specific-sized watershed. In this case, 1000 pixels. (for this thought exercise, watershed is to mean any point that flows through a pour point, regardless ...
4
votes
0answers
164 views

How to assign attributes from hydrologic sinks to upstream features? [closed]

I have a large hydrology geometric network with more than 300 sinks and roughly 150 barriers. I'd like to have the SinkID added to the attributes of the barriers (some individual networks have a ...
3
votes
1answer
68 views

Verifying the number of times a line crosses other lines

I have a series of lines that represent streams. I have a stream line and two flowpath lines in one feature class and two banklines in another feature class. Total of five lines. I then have a feature ...
3
votes
1answer
274 views

Mapping latlng values to a point on a HRAP grid

I have a copy of some NWS rainfall data loaded into a PostGIS database. Given a lat lng point, I want to find the rainfall for that given day. The original data are in XMRG format and projected ...
3
votes
1answer
226 views

Calculating Mean Upslope slope, curvature, etc

I'm trying to generate rasters whose values summarize the mean value of a given parameter (slope, curvature, etc.) of the upslope terrain. I feel like this should be doable using only a flow ...
3
votes
2answers
814 views

Determine direction of rivers, which villages lie upstream and which downstream

I want to determine which villages lie upstream and which villages lie downstream big cities built on the side of rivers in Indonesia. I have the .shp file of villages and cities, the .shp file of all ...
3
votes
1answer
270 views

Looking for Fortran code calculating drainage basin area

I am working in a project of glacier mass balance. For my project I want to integrate the area of the drainage basin in a glaciological system model (GSM). As the drainage area changes with time due ...
3
votes
0answers
138 views

How to determine longest length of segmented polylines representing rivers? [duplicate]

I have a series of shapefiles using polylines to represent the hydro network of a region. As you can see in the picture, these polylines go into great detail. These polylines are very segmented even ...
3
votes
0answers
380 views

How to calculate runoff in Rainfall Analysis?

I have 30 years daily rainfall data. How can i calculate the mean monthly runoff, minimum monthly runoff and maximum monthly runoff with the available rainfall data using GIS? I would like to use ...
3
votes
0answers
111 views

Which geostatistical tools to use to determine surface changes over 40 years?

I have a data from the Weather station with SWEmax (snow water equivalent) collected over 40 years. I need to interpolate the data over my river's watershed and then, somehow, determine the ...
3
votes
0answers
189 views

Pipe Network: Computing the inflows for systems with multiple reservoir (input source)

Let's say, for the sake of simplicity, we have the following Y Shape water pipe network: S1 and S2 are the reservoirs ( input source), Sout is the water demand where water is drawn out for ...
2
votes
1answer
606 views

How to know if flow accumulation map reflects true catchment areas?

I have calculated flow accumulation (img file) using this DEM (img file), which is 0.5 degree resolution, using arcmap. I am wondering if the cell accumulation value can directly be translated into ...
2
votes
1answer
253 views

Spatial Analysis - Calculate a cells elevation (height) above the nearest stream cell

I have searched for some ideas on how to formulate this analysis, but have come up short. I imagine there is a pretty straight forward answer; any help would be greatly appreciates. Data: DEM, ...
2
votes
2answers
596 views

Arcmap 10 restrict Flow Accumulation

I am working with the Flow Accumulation tool in ArcMap 10's spatial analyst hydrology tools. This tool calculates the total number of raster cells that flow into a given cell. However, for my ...
2
votes
2answers
166 views

River drain: r.watershed to vector is not working

I want to vertorize the result of r.watershed (accumulation). After using r.to.vect I got the message that I have to use r.thin before. So I did, but the message comes again and again. What I am ...
2
votes
1answer
283 views

Can anyone point me to a dataset (shapefile or other format) for the North American Continental Divide?

I'm looking for a more detailed dataset than the 1:2,000,000 shapefile available from the National Atlas, preferably one suitable for use at 1:24,000.
2
votes
2answers
105 views

Upstream to a river and tributary of a river - What is the underlying difference

What is the difference between a stream/ river upstream to a river A and a tributary of River A? I know that all tributaries are upstream to its river (A) and feeds into river A, but can there be a ...
2
votes
1answer
96 views

Storm Water flooding

Is there a method in Arc Gis for mapping storm water runoff in an urban environment assuming that the sewers are at full capacity. I just want to map roughly where the water will flow over the land ...
2
votes
2answers
1k views

Error running ArcHydro tools function in Arcmap

I am trying to run a function from ArcHydro tools in Arcmap 10.1; Sink evaluation. But before it can finish it returns an error message, that, frankly, I don't understand at all. It goes ...
2
votes
1answer
171 views

Inland / crater watershed delination

Even though watershed delineation is a quite popular matter here, I have what seems to be a somewhat unusual demand. I start with a DEM which is constituted of a series of craters, all centered on ...
2
votes
2answers
212 views

Flow Accumulation in R

My apologies for such a general question. Is there an ArcGIS like implementation of Flow Accumulation for R? What I am trying to avoid: Using ArcGIS; Using Grass; Using RpyGEO (but will if need be) ...
2
votes
2answers
85 views

How to determine stream channel Reach locations?

I have a stream network and want to determine stream reach locations In attached figure, Reach 4 is at the junction of sub2 and sub5, and Reach 3 is at the junction of sub1 and sub4. Any suggestions ...
2
votes
1answer
60 views

Where can I obtain Water Virtual Flow Segments for Minnesota?

This is a cross-border task. I already have this data for Ontario, Canada but I also need to complete the model for a large lake that is essentially split in half between the two countries. ...
2
votes
1answer
47 views

Determining steady flow in HEC_RAS 4.0

While using HEC-RAS 4.0 Beta, how to set PF1 in Steady Data Flow?
2
votes
0answers
105 views

Creating water surface from vector line in QGIS

I want to create a raster surface representing the flood level in a creek based on output from a 1D hydraulic model. I receive a 3D profile of the water surface in a creek line as a 3D Polyline ...
2
votes
1answer
64 views

Geoprocessing in 3D [closed]

I am looking for some advice regarding suitable software for geoprocessing in three dimensions. Specifically, I need to regularly undertake the following tasks: Intersect a line with a surface and ...
1
vote
3answers
859 views

How To find the Catchment Area for a Dam?

I have a DEM of my study area, and polyline shapefile of the Dams in that area. I have run the standard Hydrology tools on it( Fill, Flow Direction & Flow Accumulation). I know that you can ...
1
vote
2answers
111 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.