Garden with Insight v1.0 Help: Translation of EPIC Code Example

class procedure EP.PercAndLatFlowByLayer_mm( 
  numLayers: integer; layerWithDrainageSystem: integer;  
  var layers: LayerStructureArray; slopeSteepness_mPm: single;  
  returnFlowTravelTime_days: single; waterTableDepth_m: single; 
  inflowingWater_mm: single; totalRunoff_mm: single;  
  timeForDrainageSystemToReducePlantStress_days: single; 
  allowPercolation, allowLateralFlow: boolean); 
var 
  layer: integer; 
  percolationLastLayer_mm, lateralFlowThisLayer_mm,  
    percolationThisLayer_mm, swOverFCUpperLayer, swOverFCThisLayer,  
    movement_mm, proportion: single; 
begin 
{ assume this function is not called if both   
percolation and lateral flow are not allowed } 
percolationLastLayer_mm := inflowingWater_mm - totalRunoff_mm; 
if numLayers > 0 then for layer := 0 to numLayers - 1 do with layers[layer] do 
  begin 
  { add water percolated from last layer  
    (if first layer, add inflowing water - runoff) } 
  addQuantity(waterContent_mm, percolationLastLayer_mm); 
  { if water table is above the bottom of this soil layer,  
   water does not move. } 
  if (waterTableDepth_m > depth_m) then  
    begin 
    EP.PercAndLatFlowForLayer_mm( 
        layer, layerWithDrainageSystem, layers,  
        slopeSteepness_mPm, percolationThisLayer_mm, 
        lateralFlowThisLayer_mm, returnFlowTravelTime_days,  
        timeForDrainageSystemToReducePlantStress_days, 
        allowPercolation, allowLateralFlow); 
    { if percolation + lateral flow exceeds water in layer,  
      reduce both proportionally } 
    if (percolationThisLayer_mm + lateralFlowThisLayer_mm > waterContent_mm) then 
      begin 
      proportion := safediv(waterContent_mm,  
          percolationThisLayer_mm + lateralFlowThisLayer_mm); 
      if allowPercolation then  
        percolationThisLayer_mm := percolationThisLayer_mm * proportion; 
      if allowLateralFlow then  
        lateralFlowThisLayer_mm := lateralFlowThisLayer_mm * proportion; 
      end; 
    { reduce water content in layer } 
    subtractQuantity(waterContent_mm,  
        percolationThisLayer_mm + lateralFlowThisLayer_mm); 
    lateralFlow_mm := lateralFlowThisLayer_mm; 
    percolation_mm := percolationThisLayer_mm; 
    end 
  else { water table is in layer } 
    begin 
    lateralFlow_mm := 0.0; 
    percolation_mm := 0.0; 
    percolationThisLayer_mm := 0.0; 
    end; 
  percolationLastLayer_mm := percolationThisLayer_mm; 
  end; 
  { now move from the bottom to the top doing two checks:  
    if soil water > porosity and if soil water > field capacity. 
    do this only if percolation is being carried out. } 
  if allowPercolation and (numLayers > 1) then 
  for layer := numLayers - 1 downto 1 do 
    begin 
    if (layers[layer].waterContent_mm > layers[layer].porosity_mm) then 
      begin 
      movement_mm := layers[layer].waterContent_mm - layers[layer].porosity_mm; 
      addQuantity(layers[layer-1].waterContent_mm, movement_mm); 
      subtractQuantity(layers[layer-1].percolation_mm, movement_mm); 
      layers[layer].waterContent_mm := layers[layer].porosity_mm; 
      end; 
    if (layers[layer].waterContent_mm > layers[layer].fieldCapacity_mm) then 
      begin 
      swOverFCUpperLayer := safediv(layers[layer-1].waterContent_mm,  
        layers[layer-1].fieldCapacity_mm); 
      swOverFCThisLayer := safediv(layers[layer].waterContent_mm,  
        layers[layer].fieldCapacity_mm); 
      if (swOverFCUpperLayer < swOverFCThisLayer) then 
        begin 
        movement_mm := EQH.UpwardMovementOverFieldCapacityForLayer_mm( 
          layers[layer].waterContent_mm, layers[layer-1].waterContent_mm,  
          layers[layer].fieldCapacity_mm, layers[layer-1].fieldCapacity_mm); 
        addQuantity(layers[layer-1].waterContent_mm, movement_mm); 
        { can allow percolation to be negative to show upward movement } 
        layers[layer-1].percolation_mm := layers[layer-1].percolation_mm - movement_mm; 
        subtractQuantity(layers[layer].waterContent_mm, movement_mm); 
        end; 
      end; 
    end; 
  end;