Wrong location of (south) tunnel exit?
1. Inclination very high: 80m over 2.5km. Other water channel tunnels in the area are more like 5m / 1km.
2. There are no signs of a tunnel exit there (no rock material below tunnel exit).
3. The La Junquera water channel at 390m asl leads to the (north) tunnel entrance. However at the tunnel exit, there is no water channel.

A better fit seems to be 28° 15.367' N, 16° 49.794' W. This is at ~390m asl and there is a water channel leading out of that tunnel exit. Please note that although I have recently been at the proposed location, I have not walked the tunnel. Therefore I cannot confidently edit the map myself.