Preliminary Delta Model

NCED Mathematics and Geomorphology Working Group
Fowler,Jerolmack,Stark,Swenson,Voller,Wollinsky

The movie of delta building shown is based on a filling in porous media analogy.

• The calculation is based on an unstructured Voronoi Finite Element Mesh.
• A background permeability of k = 1 is used.
• Channels are simulated by assigning a permeability of k = 5.
• Initially a short diagonal channel (2.5 units wide) starting from the bottom left and extending for 7 units is imposed by setting the nodal permeability to k = 5.
• The permeability of ALL OTHER nodes is set to the background value of k =1
• As the filling proceeds the following rule are used to extended the channels the channel network

  At periodic points in time, the domain is swept and at EACH water node point P,

  IF

  • One and only one neighboring node to node P is on the land, AND
  • At least one neighboring node (nb) is in an existing channel (k_nb = 5)

  THEN a channel is created at node P be re-setting its permeability to k_P = 5.

   

• NOTE THAT, Apart from the initial diagonal channel NO OTHER channels are imposed, i.e., the majority of channels shown are created as the simulation evolves, by the rule given above
• ALSO NOTE THAT This simulation should only be viewed as an ILLUSTRATION of how a self evolving channel bifurcation and branching can be incorporated into a porous filling analogy. It is stressed that in this simulation only the starter channel is imposed