Model help:MARSSIM

MARSSIM

The MARSSIM model is a landform evolution model primarily focuses on relatively long temporal scales (relative to the timescale for noticeable landform change) through fluvial and mass wasting processes.

Model introduction

The program is designed be computationally efficient such that individual runs can be done on a modern microcomputer in no more than a few tens of hours. The more recent additions to the model have focused on processes relevant to planetary landscapes, including lava flows, groundwater seepage and sapping, impact cratering, surface-normal accretion and ablation, and volatile redistribution by radiation-induced sublimation and recondensation. Individual process formulations vary from completely heuristic to modestly mechanistic. Important limitations for some potential applications are the assumption of a single representative bed material grain size in the fluvial system and no tracking of internal stratigraphy of sedimentary deposits.

Model parameters

Parameter	Description	Unit
Input directory	-	-
MARSSIM application title	-	-
Variable information filename	-	-

Parameter	Description	Unit
Random seed	an integer random seed	-
Switch for new simulation	If set to 1, start a new simulation. Otherwise, continue from a saved state	-
Switch for fluvial and slope modeling	If set to 1, fluvial and slope processes are modeled	-
Switch for impact crater modeling	If set to 1, impact craters are modeled	-
Switch for lava inundation	If set to 1, lava inundation is modeled	-
Switch for eolian deposition	If set to 1, eolian transport is modeled	-
Switch for ocean processes	If set to 1, ocean processes is modeled	-
Switch for accretion and ablation	If set to 1, model accretion and ablation	-
Switch for lake evaporation	If set to 1, model runoff and evaporation with lakes	-
Number of columns for DEM	-	-
Number of rows for DEM	-	-
Number of vertical cells	-	-
Grid cell size	Grid cell size arbitrary units. See conversion factor below	-
Vertical scale units	Elevation units (vertical). Must as same as grid cell size units (horizontal)	-
Convert-to-meters factor	Factor to convert grid cell size and vertical scale units to meters	-
Switch for variable erosion rate	If set to 1, erosion rate will vary in time in the specified manner. Otherwise, model parameters are constant	-
Boundary lowering rate	Rate at which the boundary is lowering over time (meter/year). To be used with a nonperiodic vertical boundary	-
Channel timestep scale factor	channel process timestep scale factor	-
Default channel time step	channel process timestep	years
Maximum timestep	Maximum allowed timestep	years
Minimum timestep	Minimum allowed timestep	years
Sediment timestep scale factor	-	-
Mass wasting timestep scale factor	-	-
I-coordinate for center of debug window	Used for debug mode	-
J-coordinate for center of debug window	Used for debug mode	-
Size of debug window, I-direction	Used for debug mode	-
Size of debug window, J-direction	Used for debug mode	-
Switch to print debug info	If set to 1, print info in specified debug window, Affects performance	-
Switch to calculate morphometric statistics	If set to 1, calculate morphometric statistics	-
Switch to use horizontal lower boundary	If set to 1, southern (lower ) boundary is level. Do not use with a periodic lower boundary	-
Switch to use non-eroding lower boundary	If set to 1, use a non-eroding lower/southern boundary can be used in conjunction with a horizontal lower boundary	-
Switch for periodic Y axis	If set to 1, use periodic boundary condition along the Y-axis	-
Switch for periodic X axis	If set to 1, use periodic boundary condition along the X-axis	-
Switch to allow flow across all boundaries	All boundaries are potential flow exits and are non-eroding	-

Parameter	Description	Unit
Starting iteration	Generally this is zero for new simulatins	-
Present time	Generally this is zero for new simulatins	years
Maximum iteration	The number of timesteps or iterations to be used in the simulation	-
Maximum simulation time	The maximum time that the simulation is allowed to run	years
Iterations between prints	The number of iterations (or timesteps) between writing out a lot of info	-
Simulation progress interval	How often to summarize simulation progress. Generally should be the same as elevinterval	-
Recalculate gradient interval	Number of interations before recalculating gradients and contributing areas (Currently hardwired)	-
Write change interval	Number of iterations before printing out information on the rate of change in gradients and flow directions (Currently hardwired)	-
Morphometric channel threshold	This has to do with the definition of where channels start when printing out morphometric statistics	-
Matrices to output	What matrices to output at Elevation_print_interval times. Each digit represents a flags are (1) elevation; (2) relative elevation; (3) D8 gradient; (4) erode_slope; (5) cfne; (6) cfnw; (7) cfw; (8) cfn; (9) cfne; (10) drainage_area; (11) relative_gradient; (12) regolith and relative resistance. Generally, only first flag is set (elevation)	-
Switch for absolute or relative elevations	If set to 1, write out absolute vs. relative elevations	-
Interval to print out shaded relief images	Shaded relief images are typically generated and saved every 50 to 100 iterations	-
Divergence Interval	-	-

Parameter	Description	Unit
Switch for wet or dry depressions	If set to 1, all depressions fill with water and overflow. Otherwise, all depressions are infinite sinks for water. Most Mars simulations have used 0, but some simulatins with non-periodic BCs use 1	-
Switch for rescale discharges	IF set to 1, then effective discharges are rescaled as a power function of contributing area (e.g., Q = KA*E, where E is typically in [0.5,1.0])	-
Discharge constant	Used with option to rescale discharges. In that case, Discharge = discharge_constantArea*discharge_exponent	m³ / s
Discharge exponent	Used with option to rescale discharges. In that case, Discharge = discharge_constantArea*discharge_exponent	m³ / s
Area factor	Generally not used	-
Rain depth	-	-
Rain standard deviation	-	-
Switch for divergence-dependent runoff	If set to 1, runoff depth functionally depends on topographic divergence (VARYIELDUSE; 0, or 1), usually not set	-
Mean convergence runoff	Only used if 'Divergence dependent runoff' is toggled on	-
High convergence runoff	Only used if 'Divergence dependent runoff' is toggled on	-
Low convergence runoff	Only used if 'Divergence dependent runoff' is toggled on	-
Iterations between recalculating evaporation rates	Only used if 'Lake evaporation' is toggled on	-
Iterations between stocahstic changes in evaporation rates	Only used if 'Lake evaporation' is toggled on	-
Mean yearly evaporation depth	-	meters
Std. deviation of mean evaporation depth	-	meters
Switch to model pelagic deposition	If set to 1, deposition of suspended sediment in enclosed basins is modeled (IMODEL_PELAGIC_DEPOSITION, 0 or 1)	-
Wash load fraction	Fraction of sediment delivered to basins that is deposited as pelagic sediment	-
Amount of post-deposition	A diffusivity that determines how much post-deposition diffusion occurs in recently-deposited pelagic sediment	-
Switch to model influent rivers	IF set to 1, incoming rivers are modeled	-

Parameter	Description	Unit
Switch to model fluvial detachment	This should only set to 0 when slope processes are being modeled and fluvial erosion, transport and deposition are not	-
Switch for explicit or implicit channel bed	If set to 1, use EXPLICIT method to model regolith depth (including bare rock). Otherwise use IMPLICIT method	-
Vegetation upland resistance	Only used if 'variable vegetation resistance' flag is set	-
Vegetation channel resistance	Only used if 'variable vegetation resistance' flag is set	-
Vegetation area minimum	Only used if 'variable vegetation resistance' flag is set	-
Vegetation area maximum	Only used if 'variable vegetation resistance' flag is set	-

Parameter	Description	Unit
Switch to write sediment diagnostics	If set to 1, detailed sediment routing information is printed (ISEDDEBUGT, 0 or 1)	-
Switch for sediment transport	If set to 1, alluvial channels, delta and fans are modeled (ISEDIMENT, 0 or 1)	-
Switch for sediment routing	If set to 1, sediment routing is modeled (ISEDIMENT, 0 or 1)	-
Switch for sediment diffusion	If set to 1, sediment diffusion is modeled (ISEDIMENT, 0 or 1)	-
Switch for no-flux lower boundary	If set to 1, a no-flux lower boundary is used (IREFLECT, 0 or 1)	-
Switch for alluvial smoothing	If set to 1, alluvial depositional surfaces (fans and deltas) are smoothed during deposition (SMOOTHSEDUSE, 0 or 1)	-
Alluvial smoothing factor	only used if 'alluvial rerouting' switch is used	-
Switch to read alluvial thickness at start	If set to 1, alluvium thickness is read at beginning of simulation (IREADALLUV, 0 or 1), generally 0	-
Switch to use an ocean	If set to 1, an ocean is used, as when modeling delta (WATERUSE, 0 or 1), set to 1 if USEWET is set to 1	-
Ocean elevation	If modeling a global ocean, set this to your assumed ocean level. Otherwise, set it to a very low value	-
Delta forest gradient	This is the forest bed gradient	-
Sediment 1 exponent	Used in sediment transport relationship	-
Sediment 2 exponent	Used in sediment transport relationship	-
Effective discharge ratio	Used in sediment transport relationship	-
Sediment gradient exponent	Used in sediment transport relationship	-
Sediment transport exponent	Used in sediment transport relationship	-
Transport factor	Generally, 40.0 for sand bed, 8.0 for gravel bed	-
Flow fraction	Set to 1 when modeling erosion by groundwater seepage	-
Sediment porosity	-	-
Sediment specific gravity	-	-
Grain size	Typical value are 0.0002 for sand and 0.02 for gravel	meters
Transport critical dim shear	Generally not changed	-
Switch to use sticky sediment routing	If set to 1, use 'sticky' VS. normal sediment. Used in an experiment to model birdfoot delta. Generally not used	-
Sticky routing critical value	Use in an experiment to model birdfoot delta. Generally, not used	-
Bedload fraction	Fraction of eroded sediment that is transported as bedload. Used for calculation of alluvial channel gradients	-

Parameter	Description	Unit
Rock weathering rate	Rate of bare rock weathering	meters/year
Weather decay rate	Determines how rapidly weathering rate decreases with increasing regolith thickness, based on terrestrial values	-
Initial regolith thickness	-	meters
Switch for two-term weathering	If set to 1, a humped weathering function is used (WEATHER2USE, 0 or 1)	-
Weathering term 2	only used if 'two term weathering' flag is set	-
Weathering decay 2	only used if 'two term weathering' flag is set	-
Switch for seepage weathering	If set to 1, seepage-dependent weathering is modeled (ISSEPAGEWEATHER, 0 or 1)	-
Seepage weathering scale factor	only used if 'Seepage weathering' flag is set	-
Seepage weathering exponent	only used if 'Seepage weathering' flag is set	-
Critical bedrock gradient	Maximum steepness of bedrock slope	-
Weather multiplier	This scales the rate of bedrock mass wasting	-
Weather divergence	If greater than 0, then rate of bedrock weathering will depend on topographic divergence	-
Switch to read initial regolith thickness	If set to 1, read initial regolith thickness from file (READREOLITH, 0 or 1)	-

Uses ports

This will be something that the CSDMS facility will add

Provides ports

This will be something that the CSDMS facility will add

Main equations

A list of the key equations. HTML format is supported; latex format will be supported in the future

Notes

Any notes, comments, you want to share with the user

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: http://csdms.colorado.edu/wiki/Special:Upload
Create link to the file on your page: [[Image:<file name>]].

Developer(s)

Name of the module developer(s)

References

Key papers

Links

Any link, eg. to the model questionnaire, etc.