Monday, August 01, 2011

Tidal Boring

As we made our way from the Anchorage area to Soldotna, we traveled along the 40 mile long Turnagain Arm. The Turnagain Arm is a fjord-like waterway that runs along the southern edge of Anchorage, and is famous for having the largest tidal range in the United States.

It also has one of 60 tidal bores in the world (only 2 are in the United States, the other being the Knik Arm to the north of Anchorage). Tidal bores occur when the tidal water rises so rapidly that a wave front is created along the leading edge. The size of Turnagain's wave front can vary from day to day, ranging from 6 inches to 6 feet, and it travels about 10 miles per hour up the Arm.

The Rangers have prepared a chart that lets visitors know which days are the best to see the most dramatic bore tides. Generally, the days around the full moon and new moon are the best. We felt really lucky when we found out that the day we would be in the area was the second-best day of this new moon cycle!

So we read the brochures and websites, and found that a good place to watch the tidal bore come in was Bird Point. The bore would reach this site 2 hours and 15 minutes after low tide in Anchorage (3:18 P.M.), or about 5:33. The literature recommended we get there 1/2 hour early, because all the times were tentative.

We got there earlier than that, and spent some time talking to park volunteers -- one of whom had a Meade LX200 telescope trained on a black bear in the neighboring hills. We also got to see several bald eagles on the shore of the Arm as they grabbed some fish for dinner. By the time 5:15 rolled around, we had quite a nice group of fellow bore-watchers.

We all eagerly scanned the water trying to see... something. No one really knew what we should be looking for, as apparently all the really experienced bore watchers had gone elsewhere. We imagined this huge wall of water, almost a tsunami, really, just rushing past us like a speeding train, hell-bent on recreating its daily journey to the end of the Arm. Hopefully, as some had heard, it would be followed by a pod of beluga whales, madly surfacing and diving as they exploited the fish harvest that came in with the tide.

We kept scanning the water, softly talking amongst ourselves about the spectacle to come. Anticipation and excitement grew. 5:30 came and went. Cameras and binoculars were ready. 5:35, still nothing.

Finally, about 5:40, a woman said, "Here it comes, I think! I see a white line!" and then a bit more hesitantly, "Is that it?"
We watched with dawning understanding that, yes, this little white line was our tidal bore. There would be no wall of water, no tsunami, no whales. Just a small line, moving at a snail's pace across the water.
It passed, and we all faded back to our cars, a little wiser about the cruel tricks of Mother Nature.

But wait... the story isn't actually over. Because the tidal bore travels about 10 miles an hour, it is quite easy to overtake it in a car, which we did. We saw a huge crowd at the next pull-off where the bore was just about to reach. So we stopped, and found what was to us a previously unknown sport -- bore surfing!

The white line of the bore was now closer to our vantage point and easier to see. The three small black dots on it are surfers:

They stay stationary, and catch the bore as it overtakes them:
And then they ride the bore as long as they can:
To move from place to place when not surfing, they stand (or kneel) on the board and use paddles. This technique may be used because the low-tide, pre-bore bottom is a very sticky, dangerous mud that can act like quicksand and entrap those who try to walk on it.
So "our" tidal bore was not as exciting as some are, apparently, and at first we felt a bit cheated. But we did get to see people surfing on what is essentially a river -- something not everybody gets to see!


Allan Leonard said...

Bore surfing -- a new word in my vocabulary! Expect to see those photos in next issue of Surfing magazine :-)

Anonymous said...

Well..Well..Well. so you got to see the tidal bore! Quite a wripple. hey. thou it was exciting to witness. so glad you got to see that!maybe the beluga whales are on the other side of the Arm! You'll have fun in Soldotna. Go to the V.C.& ck out the Fish outside.Take picture! Kenai N.W.R will be a big adventure and surrounding area. so glad you are doing IT ALL!! the best!birdladyd