Do I believe my eyes !!! An aquaduct is a water carrier which could make use of many sorts of mediums; one of which could be a tunnel, but at a paltry 8.8miles can hardly be significant.
Two tunnels with far greater lengths immeadiatly spring to mind: thefirst is the northern line on the London Underground which at one time held the record for the longest tunnel and second is the Channel Tunnel (Folkesstone to Sandgatte in France) which is in excess of twenty-one miles. I also have a sneaky suspicion that those crafty Japanese have a tunnel even longer than these two.
Best Regards, Lord Hawksmill VII.