TISC software

Check the Youtube demo playlist.

Main related scientific publications:

Scientific applications of this software to geological regions:

Applications of interest for industry partners:

Tectonics, Isostasy, Surface transport, Climate

TISC is a geodynamic numerical model combining computer modeling techniques to investigate the interplay between lithospheric-scale tectonics and erosion/sedimentation at the Earth's surface. TISC is a code that integrates the calculation of lithospheric flexure, kinematic fault deformation, and surface mass transport (erosion/transport/sedimentation) along drainage networks. In other words, TISC is a software that simulates the evolution of 3D large-scale sediment transport together with tectonic deformation and lithospheric isostatic movements on geological time scales. TISC stands for Tectonics, Isostasy, Surface transport, and Climate.

Take a look at the documentation wiki and download TISC at GitHub. TISC is available for Linux / OS X platforms only.

The Landscape Evolution Model (LEM) component of TISC can deal with closed (internally-drained, endorheic) basins and finds the equilibrium between precipitation in drainage basins and evaporation in terminal lakes. Orographic precipitation is also calculated. Relative to other existing LEMs (Child, Cascade, Eros, ...), TISC explicitly handles lakes forming in local topographic minima, finding the outlet of such water bodies, and accounting for their role as hydrological and sedimentary sinks. It also accounts for internal drainage (endorheism) depending on the collected runoff and the lake's surface evaporation, explicitly calculating the extension of the resulting closed-drainage lakes. It also tracks sediment horizons in the sedimentary basins. TISC uses a fixed rectangular mesh for the finite-difference method. Water flow is at steady state.

Particular attention is given to the formation of sedimentary basins, with a full track of the source-to-sink balance between erosion and sedimentation. Further information in these papers (G-C, 2002, Basin Res., G-C et al., 2003) showing first results of this numerical model.

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; yellow for sediment). See the applicability of TISC to model foreland basins or erosional craters.

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

Precipitation and evaporation

The model can incorporate detailed approaches to orographic precipitation and evaporation, adopting the Clausius-Clapeyron equations.

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 erosion and 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.

See also our Augmented Reality Sandbox experiments for science dissemination.

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.