.. _doc.MUSTANG.present:

General presentation of sediment module MUSTANG
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This module is activated with the keys : 
           | coupled with **MARS** : 
           | **key_sedim_MUSTANG** associated with **key_substance** (:ref:`doc.module.substance`) and **key_MARS**
           |  
           | coupled with **CROCO** : 
           | **MUSTANG** associated with **SUBSTANCE** (:ref:`doc.module.substance`) 
   
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 * It takes into account a sedimentary compartment with the laws of sediment behavior and the water column with the transport of particulate subtances
 * This module has been developped by Le Hir *et al*, coupled with the hydrodynamic model **SiAM**. Then, it has continued to evolve, coupled with the parallelized hydrodynamic model **MARS**.
 * It is now renamed **MUSTANG** (*MUd and Sand TranSport modelliNG*) and is in the process of been coupled with other hydrodynamic codes.

 
 *  There are **2 versions** :
	* **Version 1** : equivalent to the previous module "mixsed" (Le Hir et al, 2011)
	* **Version 2** : new version developped by Mengual & Le Hir (2018), which includes bedload processes (Rivier et al, 2017) 


 * "Constitutive" particulate variables, which are constitute the sediment (mass=kg), are classified into several types :
    * **gravel** : transported bedload
    * **sand**   : transported bedload and in suspension
    * **mud**    : transported in suspension

 * "non constitutive" particulate variables, like for example trace metals, bacteria, nitrogen, organic matter, are also managed into the sediment and their mass unit can be expressed according to the user's choice (mole, nmole, gram, etc.)
 * "dissolved" variables are also estimated into the interstitial waters. 

 * This module adds the settling and flocculation processes to the transport of particulate variables in water column (3D). 

 * The sedimentary column is treated 1DV (in each grid cell model), with a variable number of layers whose thickness, porosity and concentration vary with time on demand by sedimentation and resuspension events. 

.. note::
   Limiting hypothesis : the grain density is identical whatever the particles

.. image:: FIG/SEDIM/sedim_fig1.jpg