Steverooo said:So, if the tunnel reaches the sea, water will only flow into it IF the valley is BELOW Sea Level (like death valley)...
...and if it is below sea level, that raises the question of why it isn't filled with water in the first place. Death Valley has the excuse that it is in the middle of a desert. While in general it is possible for a prairie to be at lower elevation than the sea, it's gotta be a prairie with minimal rainfall.