https://github.com/mauro3/wherethewaterflows.jl
Hydrolocial water flow routing on digital elevation models
https://github.com/mauro3/wherethewaterflows.jl
Last synced: 10 months ago
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Hydrolocial water flow routing on digital elevation models
- Host: GitHub
- URL: https://github.com/mauro3/wherethewaterflows.jl
- Owner: mauro3
- License: mit
- Created: 2019-10-30T10:42:57.000Z (about 6 years ago)
- Default Branch: master
- Last Pushed: 2024-05-21T15:53:46.000Z (over 1 year ago)
- Last Synced: 2024-05-22T14:31:24.989Z (over 1 year ago)
- Language: Julia
- Homepage:
- Size: 1.1 MB
- Stars: 13
- Watchers: 2
- Forks: 3
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# WhereTheWaterFlows
[](https://github.com/mauro3/WhereTheWaterFlows.jl/actions)
[](https://ci.appveyor.com/project/mauro3/WhereTheWaterFlows-jl)
[](https://codecov.io/gh/mauro3/WhereTheWaterFlows.jl)
[](https://doi.org/10.5281/zenodo.7086860)
This package allows to calculate water flow paths on digital elevation models (DEMs).
This package implements the D8 flow routing algorithm [1] as well as a
basin-filling algorithm, also by [1]. In its implementation it uses a
O(n), recursive algorithm similar as in [2]. Due to recursion it can run
into a stackoverflow error on very large DEMs.
This code is reasonably fast: flow routing on a DEM of Antarctica of
about 2e8 points (14000x14000) with 150000 depressions takes about 30s
on my laptop (Ryzen 4750U).
Example of upslope area calculated in below example.
## Manual
The main function of this package is `waterflows`, please refer to its
doc-string. Here a simple example using it:
```julia
using WhereTheWaterFlows, GLMakie
const WWF = WhereTheWaterFlows
"Synthtic DEM with a few maxs and mins"
function peaks2(n=100, randfac=0.05)
coords = range(-pi, pi, length=n)
return coords, coords, sin.(coords) .* cos.(coords') .-
0.7*(sin.(coords.+1) .* cos.(coords')).^8 .+
randfac*randn(n,n)
end
x,y,dem = peaks2(200)
area, slen, dir, nout, nin, sinks, pits, c, bnds = waterflows(dem)
# log-upslope area as well as pits (sinks)
plt_area(x, y, area, pits)
# catchments
plt_catchments(x,y,c)
# A single catchment of some point. Choose one with large catchment:
i, j = 50, findmax(area[50,:])[2]
cc = catchment(dir, CartesianIndex(i,j))
heatmap(x,y,cc)
scatter!(x[i], y[j], markersize=50)
# stream length
heatmap(x,y,slen)
demf = fill_dem(dem, sinks, dir)
# "lake-depth"
heatmap(x, y, demf.-dem)
```
In the `example/` folder there are two more complicated examples. One
showcases the ability to route several quantities at once with
self-feedback via the `feedback_fn`.
### Post-processing
There are the following function (see their docs for details):
- `catchment` -- determine the catchment of a point or a set of points
- `catchments` -- determine the catchment of several sink areas (each
defined by a set of points)
- `catchment_flux` -- the total flux or source area in a particular catchment
- `prune_catchments` -- remove catchments smaller than a certain size
- `fill_dem` -- fill the depressions of a DEM
# References
[1] O’Callaghan, J. and Mark, D.: The extraction of drainage networks
from digital elevation data, Comput. Vision Graph., 28, 323–344,
1984. [download via google scholar](https://scholar.google.ch/scholar?hl=en&q=The extraction of drainage networks from digital elevation data)
[2] Braun, J. and Willett, S.D.: A very efficient O(n), implicit and
parallel method to solve the stream power equation governing
fluvial incision and landscape evolution
panel [doi](https://doi.org/10.1016/j.geomorph.2012.10.008)