do_beach_sediment_movement.cpp

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/* ==============================================================================================================================
 
   This file is part of CoastalME, the Coastal Modelling Environment.
 
   CoastalME 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, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
==============================================================================================================================*/
#include <assert.h>
 
#include <cmath>
 
#include <cfloat>
 
#include <iostream>
using std::cout;
using std::endl;
 
#include <string>
using std::to_string;
 
#include <algorithm>
using std::stable_sort;
 
#include "cme.h"
#include "simulation.h"
#include "coast.h"
 
//===============================================================================================================================
//===============================================================================================================================
bool bPolygonAndAdjCompare(const vector<int> &nVLeft, const vector<int> &nVRight)
{
   // Each row (vector) of this vector-of-vectors is:
   // 0: This-polygon global ID (not used)
   // 1: This-polygon coast ID (in down-coast seq when sorted)
   // 2: This-polygon down-coast (true) or up-coast (false) sediment movement
   // 3 and subsequent: if sediment movement is down-coast, coast IDs of down-coast adjacent polygons; if sediment movement is up-coast, coast IDs of up-coast adjacent polygons
 
   bool bDownCoastLeft = nVLeft[2];
   bool bDownCoastRight = nVRight[2];
 
   if (bDownCoastLeft)
   {
      // LHS polygon is down-coast. First, deal with polygon 0
      if (nVLeft[1] == 0)
         // Do not swap LHS and RHS polygons
         return true;
 
      if (nVRight[1] == 0)
         // Swap LHS and RHS polygons
         return false;
 
      if ((nVLeft.size() >= 4) && (nVRight.size() >= 4))
      {
         // Search the adjacent polygons of the LHS argument, is there an "off edge" amongst them?
         bool bLHSOffEdge = false;
 
         for (unsigned int n = 3; n < nVLeft.size(); n++)
         {
            if (nVLeft[n] == INT_NODATA)
            {
               bLHSOffEdge = true;
               break;
            }
         }
 
         if (bLHSOffEdge)
            // Yes, there is an "off edge" among the adjacent polygons of the LHS polygon: so swap LHS and RHS polygons
            return false;
 
         // Search the adjacent polygons of the RHS argument, is there an "off edge" amongst them?
         bool bRHSOffEdge = false;
 
         for (unsigned int n = 3; n < nVRight.size(); n++)
         {
            if (nVRight[n] == INT_NODATA)
            {
               bRHSOffEdge = true;
               break;
            }
         }
 
         if (bRHSOffEdge)
            // Yes, there is an "off edge" among the adjacent polygons of the LHS polygon: do not swap LHS and RHS polygons
            return true;
 
         // Do we have a local change of sediment direction?
         if (! bDownCoastRight)
            // Yes, there is a change of sediment direction between this and the adjacent polygon. Keep the existing sequence
            return true;
 
         // Now sort out polygon-to-polygon dependencies. We need to put 'target' polygons after 'source' polygons, so that the source is processed before the target. So is the RHS polygon among the adjacent polygons of the LHS polygon?
         bool bLeftFound = false;
 
         for (unsigned int n = 3; n < nVLeft.size(); n++)
         {
            if (nVLeft[n] == nVRight[1])
               bLeftFound = true;
         }
 
         if (bLeftFound)
            // Yes, the RHS polygon is among the adjacent polygons of the LHS polygon, so uncons sediment movement is from the LHS polygon to the RHS polygon, and so down-coast (i.e. along the coast in the direction of increasing coastline point numbers). Keep the existing sequence
            return true;
 
         // Is the LHS polygon among the adjacent polygons of the RHS polygon?
         bool bRightFound = false;
 
         for (unsigned int n = 3; n < nVRight.size(); n++)
         {
            if (nVRight[n] == nVLeft[1])
               bRightFound = true;
         }
 
         if (bRightFound)
            // Yes, the LHS polygon is among the adjacent polygons of the RHS polygon, so uncons sediment movement is from the RHS polygon to the LHS polygon, and so up-coast (i.e. along the coast in the direction of decreasing coastline point numbers). Swap them
            return false;
      }
 
      // Neither polygon has an "off edge", and each polygon does not have the other polygon's coast ID amongst its list of adjacent polygons. So just put the polygon in increasing own-coast sequence
      if (nVLeft[1] < nVRight[1])
         return true;
 
      else
         return false;
   }
 
   else
   {
      // LHS polygon is up-coast. First, deal with polygon 0
      if (nVLeft[1] == 0)
         // Swap LHS and RHS polygons
         return false;
 
      if (nVRight[1] == 0)
         // Do not swap LHS and RHS polygons
         return true;
 
      if ((nVLeft.size() >= 4) && (nVRight.size() >= 4))
      {
         // Next, search the adjacent polygons of the LHS argument, is there an "off edge" amongst them?
         bool bLHSOffEdge = false;
 
         for (unsigned int n = 3; n < nVLeft.size(); n++)
         {
            if (nVLeft[n] == INT_NODATA)
            {
               bLHSOffEdge = true;
               break;
            }
         }
 
         if (bLHSOffEdge)
            // Yes, there is an "off edge" among the adjacent polygons of the LHS polygon: so do not swap LHS and RHS polygons
            return true;
 
         // Search the adjacent polygons of the RHS argument, is there an "off edge" amongst them?
         bool bRHSOffEdge = false;
 
         for (unsigned int n = 3; n < nVRight.size(); n++)
         {
            if (nVRight[n] == INT_NODATA)
            {
               bRHSOffEdge = true;
               break;
            }
         }
 
         if (bRHSOffEdge)
            // Yes, there is an "off edge" among the adjacent polygons of the LHS polygon: swap LHS and RHS polygons
            return false;
 
         // Do we have a local change of sediment direction?
         if (! bDownCoastRight)
            // Yes, there is a change of sediment direction between this and the adjacent polygon. Keep the existing sequence
            return true;
 
         // Now sort out polygon-to-polygon dependencies. We need to put 'target' polygons after 'source' polygons, so that the source is processed before the target. So is the RHS polygon among the adjacent polygons of the LHS polygon?
         bool bLeftFound = false;
 
         for (unsigned int n = 3; n < nVLeft.size(); n++)
         {
            if (nVLeft[n] == nVRight[1])
               bLeftFound = true;
         }
 
         if (bLeftFound)
            // Yes, the RHS polygon is among the adjacent polygons of the LHS polygon, so uncons sediment movement is from the LHS polygon to the RHS polygon, and so down-coast (i.e. along the coast in the direction of increasing coastline point numbers). Keep the existing sequence of polygons
            return true;
 
         // Is the LHS polygon among the adjacent polygons of the RHS polygon?
         bool bRightFound = false;
 
         for (unsigned int n = 3; n < nVRight.size(); n++)
         {
            if (nVRight[n] == nVLeft[1])
               bRightFound = true;
         }
 
         if (bRightFound)
            // Yes, the LHS polygon is among the adjacent polygons of the RHS polygon, so uncons sediment movement is from the RHS polygon to the LHS polygon, and so up-coast (i.e. along the coast in the direction of decreasing coastline point numbers). Swap the LHS and RHS polygons
            return false;
      }
 
      // Neither polygon has an "off edge", and each polygon does not have the other polygon's coast ID amongst its list of adjacent polygons. So just put the polygons in decreasing own-coast sequence
      if (nVLeft[1] < nVRight[1])
         return false;
 
      else
         return true;
   }
 
   // Default return value, should never get here
   return true;
}
 
//===============================================================================================================================
//===============================================================================================================================
int CSimulation::nDoAllActualBeachErosionAndDeposition(void)
{
   for (int nCoast = 0; nCoast < static_cast<int>(m_VCoast.size()); nCoast++)
   {
      int nRet;
 
      if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
         LogStream << m_ulIter << ": Calculating unconsolidated sediment transport" << endl;
 
      // Update the values of pre-existing unconsolidated sediment, for all three size classes, to include unconsolidated sediment derived from platform erosion, cliff collapse, and sediment input events
      AllPolygonsUpdateStoredUncons(nCoast);
 
      if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
      {
         WritePolygonSedimentBeforeMovement(nCoast);
         WritePolygonPotentialErosion(nCoast);
      }
 
      // Now route actually-eroded sand/coarse sediment to adjacent polygons, or off-grid. Sort polygons first
      // Each row (vector) of this vector-of-vectors is:
      // 0: This-polygon global ID
      // 1: This-polygon coast ID (in down-coast seq when sorted)
      // 2: This-polygon down-coast (true) or up-coast (false) sediment movement
      // 3 and subsequent: if sediment movement is down-coast, coast IDs of down-coast adjacent polygons; if sediment movement is up-coast, coast IDs of up-coast adjacent polygons
      vector<vector<int> > nVVPolyAndAdjacent;
      vector<int> nVPolyAndAdj;
 
      for (int nn = 0; nn < m_VCoast[nCoast].nGetNumPolygons(); nn++)
      {
         CGeomCoastPolygon const* pPolygon = m_VCoast[nCoast].pGetPolygon(nn);
         nVPolyAndAdj.clear();
 
         // The first [0] nVPolyAndAdj array item is the polygon's global ID
         nVPolyAndAdj.push_back(pPolygon->nGetGlobalID());
 
         // The second [1] nVPolyAndAdj array item is the polygon's down-coast ID
         nVPolyAndAdj.push_back(pPolygon->nGetCoastID());
 
         if (pPolygon->bDownCoastThisIter())
         {
            // Sediment is leaving this polygon in a down-coast direction. Set this as the third [2] nVPolyAndAdj array item
            nVPolyAndAdj.push_back(true);
 
            // Fourth [3] and subsequent nVPolyAndAdj array items are the down-coast seqs of adjacent down-coast polygons
            for (int nAdj = 0; nAdj < pPolygon->nGetNumDownCoastAdjacentPolygons(); nAdj++)
            {
               // Save the coast ID of each down-coast adjacent polygon
               int nAdjPolyID = pPolygon->nGetDownCoastAdjacentPolygon(nAdj);
               nVPolyAndAdj.push_back(nAdjPolyID);
            }
         }
 
         else
         {
            // Sediment is leaving this polygon in an up-coast direction. Set this as the third [2] nVPolyAndAdj array item
            nVPolyAndAdj.push_back(false);
 
            // Fourth [3] and susequent nVPolyAndAdj array items are the down-coast IDs of adjacent up-coast polygons
            for (int nAdj = 0; nAdj < pPolygon->nGetNumUpCoastAdjacentPolygons(); nAdj++)
            {
               // Save the coast ID of each up-coast adjacent polygon
               int nAdjPolyID = pPolygon->nGetUpCoastAdjacentPolygon(nAdj);
               nVPolyAndAdj.push_back(nAdjPolyID);
            }
         }
 
         // Save this 'row'
         nVVPolyAndAdjacent.push_back(nVPolyAndAdj);
      }
 
      // Write out the unsorted polygon sequence
      if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
         WritePolygonUnsortedSequence(nCoast, nVVPolyAndAdjacent);
 
      // OK, now sort the array using bPolygonAndAdjCompare(), so that 'target' polygons are processed after 'source' polygons NOTE: crashes if just use "sort", related to this? https://stackoverflow.com/questions/18291620/why-will-stdsort-crash-if-the-comparison-function-is-not-as-operator
      stable_sort(nVVPolyAndAdjacent.begin(), nVVPolyAndAdjacent.end(), bPolygonAndAdjCompare);
 
      // And check for circularities i.e. where poly X -> poly Y -> poly X. Note that we only look for two-way circularities. i.e. we ignore poly A -> poly B -> Poly C -> poly A patterns. These are probably pretty rare, however
      vector<int> VnSourcePolygons;
 
      for (int n = 0; n < static_cast<int>(nVVPolyAndAdjacent.size()); n++)
      {
         int nThisPoly = nVVPolyAndAdjacent[n][1];
         VnSourcePolygons.push_back(nThisPoly);
 
         for (int m = 3; m < static_cast<int>(nVVPolyAndAdjacent[n].size()); m++)
         {
            // Check the adjacent polygon(s) for circularities
            int nToFind = nVVPolyAndAdjacent[n][m];
            vector<int>::iterator it = find(VnSourcePolygons.begin(), VnSourcePolygons.end(), nToFind);
 
            if (it != VnSourcePolygons.end())
            {
               // Uh-oh: this adjacent polygon is in the list of previously-processed source polygons. So store the coast ID numbers of the polygons with circularity in both polygons
               CGeomCoastPolygon* pPoly = m_VCoast[nCoast].pGetPolygon(nThisPoly);
               pPoly->AddCircularity(nToFind);
 
               pPoly = m_VCoast[nCoast].pGetPolygon(nToFind);
               pPoly->AddCircularity(nThisPoly);
            }
         }
      }
 
      if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
         WritePolygonSortedSequence(nCoast, nVVPolyAndAdjacent);
 
      int nNumPolygons = m_VCoast[nCoast].nGetNumPolygons();
 
      // Now process all polygons and do the actual (supply-limited) unconsolidated sediment movement
      for (int nPoly = 0; nPoly < nNumPolygons; nPoly++)
      {
         int nPolygon = nVVPolyAndAdjacent[nPoly][1];
         CGeomCoastPolygon* pPolygon = m_VCoast[nCoast].pGetPolygon(nPolygon);
 
         // // DEBUG CODE =====================
         // int nUpCoastProfile = pPolygon->nGetUpCoastProfile();
         // CGeomProfile* pUpCoastProfile = m_VCoast[nCoast].pGetProfile(nUpCoastProfile);
         // int nDownCoastProfile = pPolygon->nGetDownCoastProfile();
         // CGeomProfile* pDownCoastProfile = m_VCoast[nCoast].pGetProfile(nDownCoastProfile);
         // int nNumUpCoastCell = pUpCoastProfile->nGetNumCellsInProfile();
         // int nNumDownCoastCell = pDownCoastProfile->nGetNumCellsInProfile();
         // LogStream << "pUpCoastProfile->nGetNumCellsInProfile() = " << nNumUpCoastCell << " pDownCoastProfile->nGetNumCellsInProfile() = " << nNumDownCoastCell << endl;
         // // DEBUG CODE =====================
 
         // // DEBUG CODE ============================================================================================================================================
         // // Get total depths of sand consolidated and unconsolidated for every cell
         // if (m_ulIter == 5)
         // {
         // double dTmpSandUncons = 0;
         // for (int nX1 = 0; nX1 < m_nXGridSize; nX1++)
         // {
         // for (int nY1 = 0; nY1 < m_nYGridSize; nY1++)
         // {
         // dTmpSandUncons += m_pRasterGrid->m_Cell[nX1][nY1].dGetTotUnconsSand();
         // }
         // }
         //
         // LogStream << endl;
         // LogStream << "*****************************" << endl;
         // LogStream << m_ulIter << ": before beach movement on nPoly = " << nPoly << " TOTAL UNCONSOLIDATED SAND ON ALL CELLS = " << dTmpSandUncons * m_dCellArea << endl;
         // }
         // // DEBUG CODE ============================================================================================================================================
 
         // Do deposition first: does this polygon have coarse deposition?
         double dCoarseDepositionTarget = pPolygon->dGetToDoBeachDepositionUnconsCoarse();
 
         if (dCoarseDepositionTarget > 0)
         {
            // It does, first tho', if we have some coarse sediment which we were unable to deposit on the previously-processed polygon (which could be the last-processed polygon of the previous timestep), then add this in
            if (m_dDepositionCoarseDiff > MASS_BALANCE_TOLERANCE)
            {
               // We had some coarse unconsolidated sediment which we were unable to deoosit on the last polygon (which could have been the last polygon of the previous iteration). So add it to the total to be deposited here
               if (m_nLogFileDetail >= LOG_FILE_HIGH_DETAIL)
                  LogStream << m_ulIter << ": nPoly = " << nPolygon << " dCoarseDepositionTarget was = " << dCoarseDepositionTarget * m_dCellArea << " adding m_dDepositionCoarseDiff = " << m_dDepositionCoarseDiff * m_dCellArea;
 
               dCoarseDepositionTarget += m_dDepositionCoarseDiff;
               m_dDepositionCoarseDiff = 0;
 
               if (m_nLogFileDetail >= LOG_FILE_HIGH_DETAIL)
                  LogStream << " dCoarseDepositionTarget now = " << dCoarseDepositionTarget << endl;
            }
 
            // OK, do deposition of coarse sediment: calculate a net increase in depth of coarse-sized unconsolidated sediment on the cells within the polygon. Note that some cells may decrease in elevation (i.e. have some coarse-sized sediment erosion) however
            double dCoarseDeposited = 0;
            nRet = nDoUnconsDepositionOnPolygon(nCoast, pPolygon, TEXTURE_COARSE, dCoarseDepositionTarget, dCoarseDeposited);
 
            if (nRet != RTN_OK)
               return nRet;
 
            double dCoarseNotDeposited = dCoarseDepositionTarget - dCoarseDeposited;
 
            if (dCoarseNotDeposited > 0)
            {
               m_dDepositionCoarseDiff += dCoarseNotDeposited;
            }
         }
 
         // Does this polygon have sand deposition?
         double dSandDepositionTarget = pPolygon->dGetToDoBeachDepositionUnconsSand();
 
         if (dSandDepositionTarget > 0)
         {
            // It does, first tho', if we have some sand sediment which we were unable to deposit on the previously-processed polygon (which could be the last-processed polygon of the previous timestep), then add this in
            if (m_dDepositionSandDiff > MASS_BALANCE_TOLERANCE)
            {
               // We had some sand unconsolidated sediment which we were unable to deoosit on the last polygon (which could have been the last polygon of the previous iteration). So add it to the total to be deposited here
               if (m_nLogFileDetail >= LOG_FILE_HIGH_DETAIL)
                  LogStream << m_ulIter << ": nPolygon = " << nPolygon << " dSandDepositionTarget was = " << dSandDepositionTarget * m_dCellArea << " adding m_dDepositionSandDiff = " << m_dDepositionSandDiff * m_dCellArea;
 
               dSandDepositionTarget += m_dDepositionSandDiff;
               m_dDepositionSandDiff = 0;
 
               if (m_nLogFileDetail >= LOG_FILE_HIGH_DETAIL)
                  LogStream << " dSandDepositionTarget now = " << dSandDepositionTarget << endl;
            }
 
            // Now do deposition of sand sediment: calculate a net increase in depth of sand-sized unconsolidated sediment on the cells within the polygon. Note that some cells may decrease in elevation (i.e. have some sand-sized sediment erosion) however
            double dSandDeposited = 0;
            nRet = nDoUnconsDepositionOnPolygon(nCoast, pPolygon, TEXTURE_SAND, dSandDepositionTarget, dSandDeposited);
 
            if (nRet != RTN_OK)
               return nRet;
 
            double dSandNotDeposited = dSandDepositionTarget - dSandDeposited;
 
            if (dSandNotDeposited > 0)
            {
               m_dDepositionSandDiff += dSandNotDeposited;
            }
 
            // // DEBUG CODE #####################
            // if (m_ulIter == 5)
            // {
            // LogStream << m_ulIter << ": after sand deposition on nPoly = " << nPoly << " dSandDepositionTarget = " << dSandDepositionTarget * m_dCellArea << " dSandDeposited = " << dSandDeposited * m_dCellArea << " dSandNotDeposited = " << dSandNotDeposited * m_dCellArea << " m_dDepositionSandDiff = " << m_dDepositionSandDiff * m_dCellArea << endl;
            //
            // double dTmpSandUncons = 0;
            // for (int nX1 = 0; nX1 < m_nXGridSize; nX1++)
            // {
            // for (int nY1 = 0; nY1 < m_nYGridSize; nY1++)
            // {
            // dTmpSandUncons += m_pRasterGrid->m_Cell[nX1][nY1].dGetTotUnconsSand();
            // }
            // }
            //
            // LogStream << m_ulIter << ": after sand deposition on nPoly = " << nPoly << " TOTAL UNCONSOLIDATED SAND ON ALL CELLS = " << dTmpSandUncons * m_dCellArea << endl;
            // }
            // // DEBUG CODE #####################
         }
 
         // Now do erosion
         double dPotentialErosion = -pPolygon->dGetPotentialErosion();
 
         if (dPotentialErosion > 0)
         {
            // There is some erosion on this polygon: process this in the sequence fine, sand, coarse. Is there any fine sediment on this polygon?
            double dExistingUnconsFine = pPolygon->dGetPreExistingUnconsFine();
 
            if (dExistingUnconsFine > 0)
            {
               // Yes there is, so crudely partition this potential value for this size class by erodibility, the result will almost always be much greater than actual (supply limited) erosion
               double dFinePotentialErosion = dPotentialErosion * m_dFineErodibilityNormalized;
 
               // Now reduce this further, by considering the total depth of fine sediment on the polygon
               double dFineErosionTarget = tMin(dFinePotentialErosion, dExistingUnconsFine);
 
               // OK, do the supply-limited erosion of fine sediment
               double dFineEroded = 0;
               nRet = nDoUnconsErosionOnPolygon(nCoast, pPolygon, TEXTURE_FINE, dFineErosionTarget, dFineEroded);
 
               if (nRet != RTN_OK)
                  return nRet;
 
               if (dFineEroded > 0)
               {
                  // We eroded some fine sediment, so add to the this-iteration total. Note that total this gets added in to the suspended load elsewhere, so no need to do it here
                  m_dThisIterBeachErosionFine += dFineEroded;
 
                  // Also add to the suspended load
                  m_dThisIterFineSedimentToSuspension += dFineEroded;
 
                  // Store the amount of unconsolidated fine beach sediment eroded for this polygon
                  pPolygon->SetBeachErosionUnconsFine(-dFineEroded);
               }
            }
 
            // Is there any sand-sized sediment on this polygon?
            double dExistingUnconsSand = pPolygon->dGetPreExistingUnconsSand();
            double dSandEroded = 0;
 
            if (dExistingUnconsSand > 0)
            {
               // There is: so crudely partition this potential value for this size class by erodibility, the result will almost always be much greater than actual (supply limited) erosion
               double dSandPotentialErosion = dPotentialErosion * m_dSandErodibilityNormalized;
 
               // Now reduce this further, by considering the total depth of sand sediment on the polygon
               double dSandErosionTarget = tMin(dSandPotentialErosion, dExistingUnconsSand);
 
               // OK, do the supply-limited erosion of sand sediment
               nRet = nDoUnconsErosionOnPolygon(nCoast, pPolygon, TEXTURE_SAND, dSandErosionTarget, dSandEroded);
 
               if (nRet != RTN_OK)
                  return nRet;
 
               if (dSandEroded > 0)
               {
                  // We eroded some sand sediment, so add to the this-iteration total
                  m_dThisIterBeachErosionSand += dSandEroded;
 
                  // Store the amount eroded for this polygon
                  pPolygon->SetBeachErosionUnconsSand(-dSandEroded);
               }
 
               // // DEBUG CODE #####################
               // if (m_ulIter == 5)
               // {
               // LogStream << m_ulIter << ": nPoly = " << nPoly << " dSandErosionTarget = " << dSandErosionTarget * m_dCellArea << " m_dDepositionSandDiff = " << m_dDepositionSandDiff * m_dCellArea << " dSandEroded = " << dSandEroded * m_dCellArea << " m_dThisIterBeachErosionSand = " << m_dThisIterBeachErosionSand * m_dCellArea << endl;
               //
               // double dTmpSandUncons = 0;
               // for (int nX1 = 0; nX1 < m_nXGridSize; nX1++)
               // {
               // for (int nY1 = 0; nY1 < m_nYGridSize; nY1++)
               // {
               // dTmpSandUncons += m_pRasterGrid->m_Cell[nX1][nY1].dGetTotUnconsSand();
               // }
               // }
               //
               // LogStream << m_ulIter << ": after sand erosion on nPoly = " << nPoly << " TOTAL UNCONSOLIDATED SAND ON ALL CELLS = " << dTmpSandUncons * m_dCellArea << endl;
               // }
               // // DEBUG CODE #####################
            }
 
            // Is there any coarse sediment on this polygon?
            double dExistingUnconsCoarse = pPolygon->dGetPreExistingUnconsCoarse();
            double dCoarseEroded = 0;
 
            if (dExistingUnconsCoarse > 0)
            {
               // There is: so crudely partition this potential value for this size class by erodibility, the result will almost always be much greater than actual (supply limited) erosion
               double dCoarsePotentialErosion = dPotentialErosion * m_dCoarseErodibilityNormalized;
 
               // Now reduce this further, by considering the total depth of coarse sediment on the polygon
               double dCoarseErosionTarget = tMin(dCoarsePotentialErosion, dExistingUnconsCoarse);
 
               // OK, do the supply-limited erosion of coarse sediment
               nRet = nDoUnconsErosionOnPolygon(nCoast, pPolygon, TEXTURE_COARSE, dCoarseErosionTarget, dCoarseEroded);
 
               if (nRet != RTN_OK)
                  return nRet;
 
               if (dCoarseEroded > 0)
               {
                  // We eroded some coarse sediment, so add to the this-iteration toal
                  m_dThisIterBeachErosionCoarse += dCoarseEroded;
 
                  // Store the amount eroded for this polygon
                  pPolygon->SetBeachErosionUnconsCoarse(-dCoarseEroded);
               }
            }
 
            // OK we now have the actual values of sediment eroded from this polygon, so next determine where this eroded sand and coarse sediment goes (have to consider fine sediment too, because this goes off-grid on grid-edge polygons). Only do this if some sand or coarse was eroded on this polygon
            if ((dSandEroded + dCoarseEroded) > 0)
            {
               if (pPolygon->bDownCoastThisIter())
               {
                  // Moving eroded sediment down-coast
                  int nNumAdjPoly = pPolygon->nGetNumDownCoastAdjacentPolygons();
 
                  for (int nn = 0; nn < nNumAdjPoly; nn++)
                  {
                     int nAdjPoly = pPolygon->nGetDownCoastAdjacentPolygon(nn);
 
                     // if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
                     // LogStream << m_ulIter << ": polygon " << nPoly << " moves sediment down-coast to polygon " << nAdjPoly << endl;
 
                     if (nAdjPoly == INT_NODATA)
                     {
                        // Sediment is leaving the grid
                        if (pPolygon->bIsCoastStartPolygon())
                        {
                           // Error: uncons sediment movement is down-coast and off-edge, but this polygon is at the up-coast end of the coastline
                           if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
                              LogStream << m_ulIter << ": " << ERR << "in sediment export. Unconsolidated sediment movement is DOWN-COAST, and sediment is leaving the grid, but polygon " << nPolygon << " is at the up-coast end of the coastline. This will result in mass balance problems." << endl;
                        }
 
                        else if (pPolygon->bIsCoastEndPolygon())
                        {
                           // This is the polygon at the down-coast end of the coastline, and uncons sediment movement is down-coast. Decide what to do based on the user setting m_nUnconsSedimentHandlingAtGridEdges
                           if (m_nUnconsSedimentHandlingAtGridEdges == GRID_EDGE_CLOSED)
                           {
                              // Closed grid edges: no uncons sediment moves off-grid, nothing is removed from this polygon, so cannot adjust sediment export
                              if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
                                 LogStream << m_ulIter << ": when adjusting sediment export, polygon " << nPolygon << " is at the down-coast end of the coastline, and actual sediment movement is DOWN-COAST. Since grid edges are closed, no sand or coarse unconsolidated sediment goes off-grid so cannot adjust sediment export. This will result in mass balance problems." << endl;
                           }
 
                           else if (m_nUnconsSedimentHandlingAtGridEdges == GRID_EDGE_OPEN)
                           {
                              // Open grid edges, so this sediment goes off-grid
                              m_dThisIterLeftGridUnconsSand += dSandEroded;
                              m_dThisIterLeftGridUnconsCoarse += dCoarseEroded;
 
                              // // DEBUG CODE ##################
                              // if (m_ulIter == 5)
                              // {
                              // LogStream << m_ulIter << ": nPoly = " << nPoly << " LOST FROM GRID = " << dSandEroded * m_dCellArea << endl;
                              // }
                              // // DEBUG CODE ##################
                           }
 
                           else if (m_nUnconsSedimentHandlingAtGridEdges == GRID_EDGE_RECIRCULATE)
                           {
                              // Re-circulating grid edges, so adjust the sediment exported to the polygon at the up-coast end of this coastline
                              int nOtherEndPoly = 0;
                              CGeomCoastPolygon* pOtherEndPoly = m_VCoast[nCoast].pGetPolygon(nOtherEndPoly);
 
                              if (dSandEroded > 0)
                              {
                                 // Add to the still-to-do total of unconsolidated sand to be deposited on the polygon at the up-coast end of this coastline
                                 pOtherEndPoly->AddToDoBeachDepositionUnconsSand(dSandEroded);
                              }
 
                              if (dCoarseEroded > 0)
                              {
                                 // Add to the still-to-do total of unconsolidated coarse sediment to be deposited on the polygon at the up-coast end of this coastline
                                 pOtherEndPoly->AddToDoBeachDepositionUnconsCoarse(dCoarseEroded);
                              }
                           }
                        }
                     }
 
                     else
                     {
                        // This polygon is not at the grid edge
                        CGeomCoastPolygon* pAdjPolygon = m_VCoast[nCoast].pGetPolygon(nAdjPoly);
                        double dBoundaryShare = pPolygon->dGetDownCoastAdjacentPolygonBoundaryShare(nn);
 
                        if (dSandEroded > 0)
                        {
                           // if (m_ulIter == 5)
                           // LogStream << m_ulIter << ": B polygon not at grid edge nPoly = " << nPoly << " nAdjPoly = " << nAdjPoly << ", dGetToDoBeachDepositionUnconsSand() on nAdjPoly is = " << pAdjPolygon->dGetToDoBeachDepositionUnconsSand() * m_dCellArea << endl;
 
                           // Add to the still-to-do total of unconsolidated sand to be deposited on the adjacent polygon
                           pAdjPolygon->AddToDoBeachDepositionUnconsSand(dSandEroded * dBoundaryShare);
 
                           // if (m_ulIter == 5)
                           // LogStream << m_ulIter << ": B after nAdjPoly = " << nAdjPoly << " AddToDoBeachDepositionUnconsSand(" << dSandEroded * dBoundaryShare * m_dCellArea << ") dGetToDoBeachDepositionUnconsSand() now = " << pAdjPolygon->dGetToDoBeachDepositionUnconsSand() * m_dCellArea << endl;
                        }
 
                        if (dCoarseEroded > 0)
                        {
                           // if (m_nLogFileDetail >= LOG_FILE_ALL)
                           // LogStream << m_ulIter << ": polygon = " << nPoly << " adjacent polygon = " << nAdjPoly << ", beach deposition 1 of uncons coarse was = " << pAdjPolygon->dGetToDoBeachDepositionUnconsCoarse() * m_dCellArea;
 
                           // Add to the still-to-do total of unconsolidated coarse sediment to be deposited on the adjacent polygon
                           pAdjPolygon->AddToDoBeachDepositionUnconsCoarse(dCoarseEroded * dBoundaryShare);
 
                           // if (m_nLogFileDetail >= LOG_FILE_ALL)
                           // LogStream << " after AddToDoBeachDepositionUnconsCoarse(" << dCoarseEroded * dBoundaryShare << ") beach deposition 1 of uncons coarse now = " << pAdjPolygon->dGetToDoBeachDepositionUnconsCoarse() * m_dCellArea << endl;
                        }
                     }
                  }
 
                  // if (m_nLogFileDetail >= LOG_FILE_ALL)
                  // LogStream << m_ulIter << ": 1 uncons sand eroded = " << dSandEroded * m_dCellArea << " 1 uncons coarse eroded = " << dCoarseEroded * m_dCellArea << endl;
               }
 
               else
               {
                  // Moving eroded sediment up-coast
                  int nNumAdjPoly = pPolygon->nGetNumUpCoastAdjacentPolygons();
 
                  for (int nn = 0; nn < nNumAdjPoly; nn++)
                  {
                     int nAdjPoly = pPolygon->nGetUpCoastAdjacentPolygon(nn);
                     // if (m_nLogFileDetail >= LOG_FILE_ALL)
                     // LogStream << m_ulIter << ": polygon " << nPoly << " moves sediment up-coast to polygon " << nAdjPoly << endl;
 
                     if (nAdjPoly == INT_NODATA)
                     {
                        // Sediment is leaving the grid
                        if (pPolygon->bIsCoastEndPolygon())
                        {
                           // Error: uncons sediment movement is down-coast and off-edge, but this polygon is at the up-coast end of the coastline
                           if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
                              LogStream << m_ulIter << ": " << ERR << "in sediment export. Unconsolidated sediment movement is UP-COAST, and sediment is leaving the grid, but polygon " << nPolygon << " is at the down-coast end of the coastline. This will result in mass balance problems." << endl;
 
                        }
 
                        else if (pPolygon->bIsCoastStartPolygon())
                        {
                           // This is the polygon at the up-coast end of the coastline, and uncons sediment movement is up-coast. Decide what to do based on the user setting m_nUnconsSedimentHandlingAtGridEdges
                           if (m_nUnconsSedimentHandlingAtGridEdges == GRID_EDGE_CLOSED)
                           {
                              // Closed grid edges: no uncons sediment moves off-grid, nothing is removed from this polygon, so cannot adjust sediment export
                              if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
                                 LogStream << m_ulIter << ": when adjusting sediment export, polygon " << nPolygon << " is at the up-coast end of the coastline, and actual sediment movement is UP-COAST. Since grid edges are closed, no sand or coarse unconsolidated sediment goes off-grid so cannot adjust sediment export" << endl;
                           }
 
                           else if (m_nUnconsSedimentHandlingAtGridEdges == GRID_EDGE_OPEN)
                           {
                              // Open grid edges, so this sediment goes off-grid
                              m_dThisIterLeftGridUnconsSand += dSandEroded;
                              m_dThisIterLeftGridUnconsCoarse += dCoarseEroded;
                           }
 
                           else if (m_nUnconsSedimentHandlingAtGridEdges == GRID_EDGE_RECIRCULATE)
                           {
                              // Re-circulating grid edges, so adjust the sediment exported to the polygon at the up-coast end of this coastline TODO 016 Check whether this causes mass balance problems, depending on the sequence of polygon processing
                              int nOtherEndPoly = 0;
                              CGeomCoastPolygon* pOtherEndPoly = m_VCoast[nCoast].pGetPolygon(nOtherEndPoly);
 
                              if (dSandEroded > 0)
                              {
                                 // Add to the still-to-do total of unconsolidated sand to be deposited on the polygon at the up-coast end of this coastline
                                 pOtherEndPoly->AddToDoBeachDepositionUnconsSand(dSandEroded);
                              }
 
                              if (dCoarseEroded > 0)
                              {
                                 // Add to the still-to-do total of unconsolidated coarse sediment to be deposited on the polygon at the up-coast end of this coastline
                                 pOtherEndPoly->AddToDoBeachDepositionUnconsCoarse(dCoarseEroded);
                              }
                           }
                        }
                     }
 
                     else
                     {
                        // This polygon is not at the grid edge
                        CGeomCoastPolygon* pAdjPolygon = m_VCoast[nCoast].pGetPolygon(nAdjPoly);
                        double dBoundaryShare = pPolygon->dGetUpCoastAdjacentPolygonBoundaryShare(nn);
 
                        if (dSandEroded > 0)
                        {
                           // if (m_ulIter == 5)
                           // LogStream << m_ulIter << ": A polygon not at grid edge nPoly = " << nPoly << " nAdjPoly = " << nAdjPoly << ", dGetToDoBeachDepositionUnconsSand() on nAdjPoly is = " << pAdjPolygon->dGetToDoBeachDepositionUnconsSand() * m_dCellArea << endl;
 
                           // Add to the still-to-do total of unconsolidated sand to be deposited on the the adjacent polygon
                           pAdjPolygon->AddToDoBeachDepositionUnconsSand(dSandEroded * dBoundaryShare);
 
                           // if (m_ulIter == 5)
                           // LogStream << m_ulIter << ": A after nAdjPoly = " << nAdjPoly << " AddToDoBeachDepositionUnconsSand(" << dSandEroded * dBoundaryShare * m_dCellArea << ") dGetToDoBeachDepositionUnconsSand() now = " << pAdjPolygon->dGetToDoBeachDepositionUnconsSand() * m_dCellArea << endl;
                        }
 
                        if (dCoarseEroded > 0)
                        {
                           // if (m_ulIter == 5)
                           // LogStream << m_ulIter << ": polygon not at grid edge nPoly = " << nPoly << " nAdjPoly = " << nAdjPoly << ", beach deposition of uncons coarse was = " << pAdjPolygon->dGetToDoBeachDepositionUnconsCoarse() * m_dCellArea << endl;
 
                           // Add to the still-to-do total of unconsolidated coarse sediment to be deposited on the adjacent polygon
                           pAdjPolygon->AddToDoBeachDepositionUnconsCoarse(+dCoarseEroded * dBoundaryShare);
 
                           // if (m_ulIter == 5)
                           // LogStream << " After AddToDoBeachDepositionUnconsCoarse(" << dCoarseEroded * dBoundaryShare << ") uncons coarse now = " << pAdjPolygon->dGetToDoBeachDepositionUnconsCoarse() * m_dCellArea << endl;
                        }
                     }
                  }
               }
            }
 
            // if (m_nLogFileDetail >= LOG_FILE_ALL)
            // LogStream << m_ulIter << ": sand eroded on poly = " << dSandEroded * m_dCellArea << " coarse eroded on poly = " << dCoarseEroded * m_dCellArea << endl;
 
         }     // if (dPotentialErosion > 0)
 
         // // DEBUG CODE ============================================================================================================================================
         // // Get total depths of unconsolidated sand for every cell
         // if (m_ulIter == 5)
         // {
         // double dTmpSandUncons = 0;
         // for (int nX1 = 0; nX1 < m_nXGridSize; nX1++)
         // {
         // for (int nY1 = 0; nY1 < m_nYGridSize; nY1++)
         // {
         // dTmpSandUncons += m_pRasterGrid->m_Cell[nX1][nY1].dGetTotUnconsSand();
         // }
         // }
         //
         // LogStream << endl;
         // LogStream << m_ulIter << ": TOTAL UNCONSOLIDATED SAND ON ALL CELLS after beach movement on nPoly = " << nPoly << " dTmpSandUncons = " << dTmpSandUncons * m_dCellArea << " (dTmpSandUncons - m_dStartIterUnconsSandAllCells) =  " << (dTmpSandUncons - m_dStartIterUnconsSandAllCells) * m_dCellArea << endl;
         //
         //    // Now get the total in all still-to-do fields of all polygons
         // double dToDoTot = 0;
         //
         // for (int nn = 0; nn < nPolygons; nn++)
         // {
         // CGeomCoastPolygon* pThisPolygon = m_VCoast[nCoast].pGetPolygon(nn);
         // dToDoTot += pThisPolygon->dGetToDoBeachDepositionUnconsSand();
         // }
         //
         // LogStream << endl  << m_ulIter << ": dToDoTot = " << dToDoTot * m_dCellArea << endl;
         // LogStream  << m_ulIter << ": dTmpSandUncons + dToDoTot = " << (dTmpSandUncons + dToDoTot) * m_dCellArea << endl << endl;
         //
         // LogStream << m_ulIter << ": m_dThisIterLeftGridUnconsSand = " << m_dThisIterLeftGridUnconsSand * m_dCellArea << endl;
         //
         // LogStream << "*****************************" << endl;
         // }
         // // DEBUG CODE ============================================================================================================================================
 
      }     // for (int n = 0; n < nNumPolygons; n++)
 
      // OK we have processed all polygons, But if there are adjacent-polygon circularities (i.e. Polygon A -> Polygon B -> Polygon A) then we may have some still-to-do deposition on at least one polygon. So look through all polygons and check their still-to-do lists
      int nPolygons = m_VCoast[nCoast].nGetNumPolygons();
 
// for (int nn = 0; nn < nPolygons; nn++)
      for (int nn = nPolygons - 1; nn >= 0; nn--)
      {
         int nThisPoly = nVVPolyAndAdjacent[nn][1];
         CGeomCoastPolygon* pThisPolygon = m_VCoast[nCoast].pGetPolygon(nThisPoly);
 
         double dSandToDepositOnPoly = pThisPolygon->dGetToDoBeachDepositionUnconsSand();
 
         if (dSandToDepositOnPoly > 0)
         {
            // There is some still-to-do deposition of sand sediment on this polygon: calculate a net increase in depth of sand-sized unconsolidated sediment on the cells within the polygon. Note that some cells may decrease in elevation (i.e. have some sand-sized sediment erosion) however
            double dSandDeposited = 0;
            nRet = nDoUnconsDepositionOnPolygon(nCoast, pThisPolygon, TEXTURE_SAND, dSandToDepositOnPoly, dSandDeposited);
 
            if (nRet != RTN_OK)
               return nRet;
 
            double dSandNotDeposited = dSandToDepositOnPoly - dSandDeposited;
 
            if (dSandNotDeposited > 0)
               m_dDepositionSandDiff += dSandNotDeposited;
 
            if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
               LogStream << m_ulIter << ": re-processing nThisPoly = " << nThisPoly << " dSandDeposited = " << dSandDeposited * m_dCellArea << " dSandNotDeposited = " << dSandNotDeposited * m_dCellArea << " m_dDepositionSandDiff = " << m_dDepositionSandDiff * m_dCellArea << endl;
         }
 
         double dCoarseToDepositOnPoly = pThisPolygon->dGetToDoBeachDepositionUnconsCoarse();
 
         if (dCoarseToDepositOnPoly > 0)
         {
            // There is some still-to-do deposition of coarse sediment on this polygon: calculate a net increase in depth of coarse-sized unconsolidated sediment on the cells within the polygon. Note that some cells may decrease in elevation (i.e. have some coarse-sized sediment erosion) however
            double dCoarseDeposited = 0;
            nRet = nDoUnconsDepositionOnPolygon(nCoast, pThisPolygon, TEXTURE_COARSE, dCoarseToDepositOnPoly, dCoarseDeposited);
 
            if (nRet != RTN_OK)
               return nRet;
 
            double dCoarseNotDeposited = dCoarseToDepositOnPoly - dCoarseDeposited;
 
            if (dCoarseNotDeposited > 0)
               m_dDepositionCoarseDiff += dCoarseNotDeposited;
 
            if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
               LogStream << m_ulIter << ": re-processing nThisPoly = " << nThisPoly << " dCoarseDeposited = " << dCoarseDeposited * m_dCellArea << " dCoarseNotDeposited = " << dCoarseNotDeposited * m_dCellArea << " m_dDepositionCoarseDiff = " << m_dDepositionCoarseDiff * m_dCellArea << endl;
         }
      }
 
      if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
         WritePolygonActualMovement(nCoast, nVVPolyAndAdjacent);
   }
 
   return RTN_OK;
}
 
//===============================================================================================================================
//===============================================================================================================================
void CSimulation::AllPolygonsUpdateStoredUncons(int const nCoast)
{
   int nNumPolygons = m_VCoast[nCoast].nGetNumPolygons();
 
   for (int nPoly = 0; nPoly < nNumPolygons; nPoly++)
   {
      CGeomCoastPolygon* pPolygon = m_VCoast[nCoast].pGetPolygon(nPoly);
 
      // Only include unconsolidated fine sediment from sediment input events, don't include any unconsolidated fine sediment from platform erosion and cliff collapse since these have gone to suspension
      double dFine = pPolygon->dGetSedimentInputUnconsFine();
      pPolygon->SetPreExistingUnconsFine(dFine);
 
      // Include unconsolidated sand sediment derived from platform erosion, cliff collapse, and sediment input events
      double dSand = pPolygon->dGetPreExistingUnconsSand() + pPolygon->dGetPlatformErosionUnconsSand() + pPolygon->dGetCliffCollapseUnconsSandDeposition() + pPolygon->dGetSedimentInputUnconsSand();
      pPolygon->SetPreExistingUnconsSand(dSand);
 
      // Include unconsolidated coarse sediment derived from platform erosion, cliff collapse, and sediment input events
      double dCoarse = pPolygon->dGetPreExistingUnconsCoarse() + pPolygon->dGetPlatformErosionUnconsCoarse() + pPolygon->dGetCliffCollapseUnconsCoarseDeposition() + pPolygon->dGetSedimentInputUnconsCoarse();
      pPolygon->SetPreExistingUnconsCoarse(dCoarse);
   }
}