Saint Anthony Falls

I attended the International Symposium on the Future of Environmental Hydraulics on May 12 in Minneapolis, organized by the St. Anthony Falls Laboratory, University of Minnesota.

Photo to the left shows St. Anthony Falls, with downtown Minneapolis in the background. Additional photos that I took can be found in my water photo album.

Hurricane Gustav on News Orleans: A Narrow Miss

Gustav has made the landfall near Cocodrie, Louisiana, 72 miles southwest of New Orleans, as a category 2 hurricane. New Orleans has avoided a direct hit, what a relief!

Map to the left shows the levee system to protect New Orleans. The levee system was breached at numerous locations during Hurricane Katrina (category 3) three years ago. The levee system has since been repaired to or beyond the pre-Katrina protection level. However, the levee system planned by the US Army Corps of Engineers to protect the city from a "100-year storm" is still being re-built or newly constructed and will not be completed by 2011.

It should be pointed out that the strength (height and speed) of a surge at a specific location depends on the approaching angle of the hurricane as well as the type and length of the channel that the initial surge would have to travel through, not just the category number. Highly sophisticated computer models are available and can be used to forecast the flood level more accurately.

I applaud the coordinated efforts by Federal, State, and local authorities to successfully inform and evacuate residents in advance. Forecasting the flood level is not yet an exact science, but it is better to be safe than sorry.

For Gustav, the surge water has now entered the city canals, and some water is splashing over the top of the Industrial Canal (the Inner Harbor Navigation Canal on the map). May the levee system in New Orleans continue to hold and the water drainage/pumping system continue to function to minimize the property damages!

(Source of Map: 2006 Report by the US Army Corps of Engineers)

Dam Operations to Help with Recovery and Reconstruction Efforts at Collapsed I-35W Bridge Site

It was reported that the recovery (sadly) efforts were hindered by the rapid and turbid river current at the collapsed I-35W Bridge site. I believe the rapid current was due to water falls upstream, and the turbid water was due to its high soil and organic contents that was made worse by debris from the collapsed bridge.

The Google map/image shows the I-35W Bridge, and the Upper and Lower St. Anthony Falls. You can see the rapid currents at downstream sides of both Falls. The I-35W Bridge is in rapid tail water of the Lower St. Anthony Falls.

To help the recovery efforts, water level was lowered in the Mississippi River at the bridge site, by opening up more the downstream Ford Dam (a part of the Lock and Dam No. 1 System). But this made the current at the bridge site even faster, thus tougher to anchor and stirring up even more debris. It was a tricky engineering that helped with the recovery efforts.

Maybe they could additionally change operations at the lock and dam systems associated with the St. Anthony Falls upstream, and lower the gates at the Coon Rapids Dam further upstream to hold more water.

Well-coordinated opeartions of downstream and upstream dams would also likely help a rapid and smooth reconstruction of the bridge.

What a horrible event! May the recovery and re-construction efforts go well!

PS: I lived in a rooming house close to the bridge while a graduate student at the University of Minnesota. I still remember the sound of I-35W traffic as well as the view of St. Anthony Falls!