static CommandCost TerraformTile_Water(TileIndex tile, DoCommandFlag flags, int z_new, Slope tileh_new)

    /* Canals can't be terraformed */

    if (IsWaterTile(tile) && IsCanal(tile)) return_cmd_error(STR_ERROR_MUST_DEMOLISH_CANAL_FIRST);

 

    /* Rivers can't be terraformed if the resulting formation is not flat or inclined */

    if (IsWaterTile(tile) && IsRiver(tile)) {

        if (!IsTileFlat(tileh_new) || !IsInclinedSlope(tileh_new)) {

            return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);

        }

    }

    return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);