waterdepth.ca

/*
    
Copyright (c) 2013 Centre for Water Systems,
                   University of Exeter

This file is part of cafloodpro.

cafloodpro is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>
*/

// Update the water depth for 
// OUTF1 constains the outflow of this step
// OUTF2 constains the outflow to erase
CA_FUNCTION waterdepth(CA_GRID grid, CA_CELLBUFF_REAL_IO WD, 
		       CA_EDGEBUFF_REAL_I OUTF1, CA_EDGEBUFF_REAL_IO OUTF2, 
		       CA_CELLBUFF_STATE_I MASK, 
		       CA_GLOB_REAL_I dt)
{
  // Initialise the grid
  CA_GRID_INIT(grid);
  
  // ERASE OUTF BUFFER 2
  for(int k=1; k<=caUpdateEdges(grid); ++k)
    caWriteEdgeBuffReal(grid,OUTF2,k,0.0);
  
  // Create the arrays which will contain the water fluxes on the
  // edges.
  CA_ARRAY_CREATE(grid, CA_REAL, FLUXES1, caEdges+1);

  // Read Mask.
  CA_STATE mask  = caReadCellBuffState(grid,MASK,0);

  // Read bit 0  (false the main cell has nodata)
  CA_STATE bit0  = caReadBitsState(mask,0,1);

  // Read bit 31 (true if the main cell is nodata in at least one
  // neighbour has data)
  CA_STATE bit31  = caReadBitsState(mask,31,32);

  // If the main cell has no data and none of the neighbour has data,
  // then do nothing.
  if(bit0 == 0 && bit31 == 0)
    return;

  // Read the fluxes of the main cell.
  caReadEdgeBuffRealEdgeArray(grid, OUTF1,0, FLUXES1);

  // Retrive the current value of the water depth.
  CA_REAL  wd  = caReadCellBuffReal(grid,WD,0);
  
  // Retrive the area of the main cell.
  CA_REAL  area = caArea(grid,0);

  CA_REAL outflux = 0.0;

  // Loop through the edges.
  for(int e=1; e<=caEdges; e++)
  {
    // If the edge is one of the edges that can be updated without
    // overwriting the buffer, the outflux is positive otherwise is
    // negative.
    if(e<=caUpdateEdges(grid))
      outflux += FLUXES1[e];
    else
      outflux -= FLUXES1[e];    
  }
  
  // Remove the outflux volume from the next step of the water depth.
  // Add the rain
  caWriteCellBuffReal(grid,WD,wd-(outflux/area));
}