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(tile) && IsInclinedSlope(tileh_new)) {
		}
		else {
			return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
		}
	}
	return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
}