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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2
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5answers
4k 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 ...
4
votes
1answer
572 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 ...
4
votes
0answers
38 views

Determining the Thalweg line of a river without bathymetry?

I have the boundaries and centerline of a river. The Thalweg line defines the deepest elevation of a watercourse (see Image taken from Google). I do not have accurate enough bathymetry or Digital ...
2
votes
1answer
69 views

Connectivity of Streams

I have a line vector layer containing streams (see image below). What is the easiest approach to determine the connectivity of each stream segment (eg. sum of upstream nodes)?
1
vote
0answers
20 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
4
votes
1answer
769 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 ...
1
vote
1answer
18 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 ...
1
vote
1answer
42 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 I have combined all these steps and run it as one in ...
4
votes
1answer
171 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 ...
18
votes
7answers
10k 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 ...
3
votes
1answer
54 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
votes
1answer
1k views

Determining direction of rivers i.e. which villages lie upstream and 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 ...
4
votes
1answer
76 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 ...
0
votes
1answer
1k views

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

I am a hydrologist and their 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 ...
3
votes
2answers
86 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 ...
3
votes
1answer
31 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 ...
1
vote
0answers
32 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 ...
0
votes
1answer
40 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 ...
0
votes
5answers
6k views

Where can I find base data shapefiles for whole US?

I am looking for the base layers for whole U.S. - roads, hydrological lines etc with flexibilities of changing symbology and labels. TIGER is a good source but it is at county level. I am running on ...
9
votes
4answers
2k 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 ...
1
vote
0answers
29 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 ...
0
votes
0answers
65 views

What is the difference between Specific Catchment Area and Total Catchment Area in hydrology?

I am getting stuck on the concepts of Total Catchment Area (TCA) and Specific Catchment Area (SCA) as I try to learn more about TOPMODEL. What do these metrics mean in hydrology? The context I ...
0
votes
0answers
188 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 ...
0
votes
0answers
22 views

building artificial dam in a canyon [duplicate]

I want to calculate the water volume dammed by a dam in a canyon. I managed to calculate the water volume but I actually need a dam in a certain place of the gorge so I can pursuit my calculations. I ...
1
vote
0answers
31 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 ...
0
votes
2answers
58 views

Are there publicly available 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 ...
3
votes
1answer
74 views

How can I select all streams downstream of a polygon

I have an ordered stream network and I want to select all stream features that contain water that has come from a certain area. To start with I'm running a select by location query to find all stream ...
1
vote
4answers
416 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 ...
3
votes
0answers
75 views

SAGA hydrological analysis in QGIS 2.8 on Mac

I am running QGIS 2.8 on a Mac machine and I want to calculate the catchment area using SAGA - Catchment Area. It starts running but after a while when QGIS wants to open the generated files there is ...
1
vote
0answers
39 views

Hydrology Analysis via SAGA - what is the unit? [closed]

I did a couple of analysis via SAGA about an area in Iceland...I've never worked with SAGA before, could anyone tell me what Units the numbers in the legends for "Catchment Area Recursive" and ...
6
votes
1answer
4k 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 ...
3
votes
4answers
147 views

How can Identify highs on a DEM?

I have a DEM and I want to find each hill and create a polygon for its area, effectively the out closed contour that encloses the hill. I can do this visually but I'm about to work on a larger area so ...
5
votes
1answer
107 views

How to run a tool from Whitebox GAT in ArcGIS?

I have a series of tools that I need to run in ArcGIS to hydrologically condition my DEM, but the first step in this process is running the Breach Depressions tool from Whitebox GAT (I have found that ...
0
votes
0answers
26 views

Manually collecting data in ModelBuilder?

I'm not sure how to phrase my question in the title. Currently I'm trying to build a model for automatic watershed delineation. the ppt.shp (snap pour point) cannot be determined until flow ...
0
votes
0answers
38 views

Batch processing Surface volume calculation in ArcMap?

I'm trying to collect the 2D area, 3D area and volume of a given basin at 0.5 meter increment in plane height, but since I want to graph the relationship between plane height and the areas and volume, ...
1
vote
1answer
57 views

reading GRASS vector map in python

I know similar questions have been asked several times, but none of the solutions seems suitable for my problem or don't work.. I computed flowlines using the r.flow tool from GRASS GIS, then I ...
2
votes
1answer
55 views

How do I find out the sea levels?

I have following elevation data of a region (the higher the altitude, the brigher the points): How can I find out, which areas are filled by water, and which not? Can I assume that if the ...
1
vote
2answers
849 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
3answers
226 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
3answers
187 views

Ways to determine winding topographic characteristics of a river

Are there any methods and/or technical guides on how to classify the degree of winding of river bodies? I have the following polygon layer of roughly 100,000 water bodies and would like to write an ...
3
votes
1answer
42 views

Watershed Tool Straight Edge Problem

I'm trying to accurately delineate a watershed into sub-basins using dams as pour points. I'm using the hydrology toolset, but I can't seem to get rid of straight edges that are along some of the ...
3
votes
1answer
2k views

Water Flow Analysis in ArcGIS Desktop?

If I know that 10,000+ gallons of water were going to be dropped at a single point how could I model where it would flow. I would prefer something that worked in ArcGIS and could create a layer.
1
vote
0answers
35 views

Automatically selecting main rivers of very branched river network using Arc Hydro? [closed]

I'm using ArcGIS 10.1 for Desktop and Arc Hydro. Is there any way to automatically select the main rivers of a very branched river network?
1
vote
0answers
143 views

How can we extract the stream order branch?

Actually I am new to GIS, so I don't know much about technical terminology. I have extracted a river network but now have a problem in distinguishing the branch order of stream (from order 1 to 2, 2 ...
2
votes
1answer
856 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 ...
1
vote
0answers
98 views

How to automatically generate pour points along stream network?

The following screenshot shows the results of a water flow analysis where I identified stream order via the Strahler method in ArcGIS. Now I need to generate watersheds for 2nd order streams and ...
0
votes
0answers
91 views

Problem in running r.sim.water

I am trying to run the r.sim.water in GRASS. I have calculated the partial derivatives dx and dy rater map using r.slope.aspect. I am using this elevation map [1] to get the time-series depth map. But ...
0
votes
0answers
52 views

How to separate shared watersheds using ArcGIS for Desktop or QGIS?

I have a similar problem than the one expressed in this question. Here's my situation : I need to have the full watershed of a point downstream of another point.The Watershed tool only gives the ...
1
vote
2answers
827 views

How to speed up batch watershed delineation?

I have a large number of pour points - approximately 250,000 for which I want to delineate the upstream watershed area using ArcHydro's "Batch Watershed Delineation". Given that it takes roughly 4-5 ...
1
vote
1answer
158 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 ...