The tunnel will have to be waterproof no matter where we build it, and there are lots of tunnels in the world directly under rivers / lakes, it’s one of the main reasons to build a tunnel.
But the city does not have the necessary infrastructure to deal with the excess water. You can water proof it all ya want but if you can’t get rid of the water it builds up and ya got flooding
The tunnel will have to be waterproof no matter where we build it, and there are lots of tunnels in the world directly under rivers / lakes, it’s one of the main reasons to build a tunnel.
But the city does not have the necessary infrastructure to deal with the excess water. You can water proof it all ya want but if you can’t get rid of the water it builds up and ya got flooding