Model help:AquaTellUs
AquaTellUs
A 2-D process–response model, AQUATELLUS, has been designed that integrates fluvio-deltaic process descriptions for large spatial and temporal scales. Over large (geological) time scales, major floods and storms are the relevant transport events.
Model introduction
AquaTellUs models fluvial-dominated delta sedimentation. AquaTellUS uses a nested model approach; a 2D longitudinal profiles, embedded as a dynamical flowpath in a 3D grid-based space. A main channel belt is modeled as a 2D longitudinal profile that responds dynamically to changes in discharge, sediment load and sea level. Sediment flux is described by separate erosion and sedimentation components. Multiple grain-size classes are independently tracked. Erosion flux depends on discharge and slope, similar to process descriptions used in hill-slope models and is independent of grain-size. Offshore, where we assume unconfined flow, the erosion capacity decreases with increasing water depth. The erosion flux is a proxy for gravity flows in submarine channels close to the coast and for down-slope diffusion over the entire slope due to waves, tides and creep. Erosion is restricted to the main flowpath. This appears to be valid for the river-channel belt, but underestimates the spatial extent and variability of marine erosion processes.
Deposition flux depends on the stream velocity and on a travel-distance factor, which depends on grain size (i.e. settling velocity). The travel-distance factor is different in the fluvial and marine domains, which results in a sharp increase of the settling rate at the river mouth, mimicking bedload dumping.
Dynamic boundary conditions such as climatic changes over time are incorporated by increasing or decreasing discharge and sediment load for each time step.
Model parameters
Uses ports
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Provides ports
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Main equations
- Lower boundary condition for sediment flux
[math]\displaystyle{ {\frac{\partial H_{x}}{\partial t_{x}}} = {\frac{\partial F}{\partial x}} + T }[/math] (1)
[math]\displaystyle{ {\frac{\partial F_{x}}{\partial x}} = {\frac{\partial F_{ero \left ( x \right )}}{\partial x}} - {\frac{\partial F_{sed \left ( x \right )}}{\partial x}} }[/math] (2)
[math]\displaystyle{ {\frac{\partial F_{ero}}{\partial x}} = k S^m Q \left ( x \right ) }[/math] (3)
[math]\displaystyle{ F = F_{in} + F_{ero} = F_{sed} + F_{out} }[/math] (4)
[math]\displaystyle{ {\frac{\partial F_{sed}}{\partial x}} = {\frac{F_{\left ( x,t \right )}}{h}} }[/math] (5)
[math]\displaystyle{ F_{sed \left ( x,t \right )} = F_{sed \left ( x-1,t \right )} - \left ( F_{sed \left (x-1,t \right )} 2 D_{coast} tan \alpha \right ) }[/math] (6)
Symbol | Description | Unit |
---|---|---|
H | topographical height | L |
t | time | T |
F | sediment flux | L^{2} / T |
T | rate of vertical tectonic movement | L / T |
x | horizontal distance | L |
F_{ero} | erosion flux | L^{2} / T |
F_{sed} | sedimentation flux | L^{2} / T |
Q_{(x)} | discharge function | L^{2} / T |
S | slope | L / L |
m | constant | - |
k | erosion efficiency | 1 / L |
F | sediment load of the water | L^{2} / T |
F_{in} | incoming sediment load | L^{2} / T |
F_{out} | outflux | L^{2} / T |
F_{(x,t)} | absolute sediment flux | L^{2} / T |
h | travel distance | L |
D_{coast} | distance from the coastline | m |
α | typical for bed friction-dominated plumes, equals to 20^{o} | - |
n | Manning's n | s / m^{1/3} |
P_{w} | wetted perimeter of a trapezoid | m^{2} |
S | bed slope | m / m |
g | gravity acceleration | m / s^{2} |
z_{0} | roughness length | m |
κ | Von Karman's constant, equals to 0.41 | - |
a | constant | - |
C | constant | - |
A_{t} | top surface area of a channel segment | m^{2} |
W_{t} | top width of a wetted trapezoidal cross section | m |
V_{w} | wetted volume of a trapezoidal channel | m |
Output
Symbol | Description | Unit |
---|---|---|
Q | discharge of water | m^{3} / s |
v | flow velocity | m / s |
d | mean channel flow depth | m |
f | friction factor | - |
R_{h} | hydraulic radius | m |
S_free | free-surface slope | m / m |
Notes
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Numerical scheme
Examples
An example run with input parameters, BLD files, as well as a figure / movie of the output
Follow the next steps to include images / movies of simulations:
- Upload file: https://csdms.colorado.edu/wiki/Special:Upload
- Create link to the file on your page: [[Image:<file name>]].
See also: Help:Images or Help:Movies
Developer(s)
Name of the module developer(s)
References
Key papers
Links
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