TISC software

Interplay between Earth's surface and deep processes 

[related scientific publications:  (Garcia-Castellanos, 2002, Basin Res.; Garcia-Castellanos et al., 2003, JGR; Fullea et al., 2009, G3]

TISC is a software combining computer modeling techniques to investigate the interplay between lithospheric-scale tectonics and erosion/sedimentation at the Earth's surface. TISC (formerly called tao3D) stands for Tectonics, Isostasy, Surface Transport, and Climate.

TISC is a numerical model that integrates quantitative models of lithospheric flexure, kinematic fault deformation, and surface mass transport (erosion/transport/sedimentation) along drainage networks. In other words, TISC is a computer program that simulates the evolution of 3D large-scale sediment transport together with tectonic deformation and lithospheric vertical movements on geological time scales. Particular attention is given to foreland sedimentary basin settings. Further information in these papers (G-C, 2002, Basin Res., G-C et al., 2003) showing first results of this numerical model.

In comparison to other existing landscape evolution models (Child, Cascade, Eros, ...), TISC can handle lakes forming in local topographic minima, it can calculate the outlet of such water bodies, and takes into account their role as hydrological and sedimentary sinks. It also accounts for internal drainage (endorheism) dependent on basin runoff and lake evaporation, explicitely calculating the extension of closed-drainage lakes. It also tracks sediment horizons in the sedimentary basins (but not sediment facies). Drawbacks: TISC uses a fixed rectangular mesh, and is oriented towards large-scale (> 100 km) modeling. And don't expect a user-friendly interface.

Take a look at the documentation wiki and download TISC at this Git repository. TISC is available for Linux platforms only.

Example of a model run (click to enlarge this animation). The panels show the evolution of the planform distribution (top view) of topography and fluvial drainage (top-left panel), outcropping lithology, river sediment load, and sediment thickness (top right), and a cross section of the model (bottom). See the applicability of TISC to model 
foreland basins or erosional craters.

Example of precipitation and erosion modeled with TISC




















5 main processes are implemented in the model using finite difference techniques in a planform (x,y) rectangular grid:

Precipitation and evaporation

The code is in currently in process of incorporating detailed approaches to orographic precipitation and evaporation, which formerly had been predefined parameters. 

River and lake drainage

The drainage river network is calculated following the maximum slope along the evolving topography. Based on the runoff distribution, the water discharge at any cell of the network is calculated as the water collected from tributary cells plus the precipitation at that cell. Lake evaporation is accounted for, enabling the model to study close endorheic basins. Both topography and the network evolves as a result of erosion, sedimentation and tectonic processes.


River sediment transport

Sediment carrying capacity is a function of water discharge and slope and determines whether a river is eroding or depositing. Suspended sediments resulting from erosion are transported through the fluvial network until they are deposited or they leave the model domain (explicit mass conservation). 

Lithospheric flexure

An elastic and/or viscoelastic plate approach is used to calculate the vertical movements of the lithosphere caused by the mass redistribution. In the classical lithospheric flexural model, the lithosphere is assumed to rest on a fluid asthenosphere and behave as a thin plate when submitted to external forces.

Tectonic deformation

Tectonic modification of the relieve and the correspondent loading of the lithosphere are calculated using a cinematic vertical shear approach (preserving the vertical thickness of the moving units during motion). 

Analogue-numerical hybrid modeling

We use a combined analogue-numerical technique to test the hypothesis that erosion/sedimentation at the Earth's surface exerts a significant effect on crustal-scale tectonics. TISC has been coupled with analogue models to simulate the potential effects that erosion may exert on the distribution of faulting and tectonic deformation of the crust. To this purpose, we have used the ISES TecLab (VU, Amsterdam), commanded by Dimitrios Sokoutis. The changes in topography in an analogue model are passed to the computer program, which calculates the spatial distribution of erosion and sedimentation. This is in turn applied back to the analogue model by manually removing/adding sand. See results and details in this paper by Persson et al., 2004.
Set-up of the analogue model using a sandbox to simulate the brittle deformation of the crust.








Planform view of the topography and drainage network (left) and erosion (blue) and sedimentation (red) rate of an analogue-numerical simulation of lithospheric folding + surface transport.
Method used to couple the results from the analogue and the numerical models. See Persson et al., 2004.
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