Friday, June 20, 2014

Research Suggests Huge Paleo-Floods On The Colorado River - What Does It Mean For Glen Canyon Dam?

The Colorado River flows along a stretch near Moab known as the "Daily"
On June 19, the LA Times ran an article about recent research done on the Colorado River near Moab, Utah. The research shows that huge paleofloods have coursed down the river within the last 2,000 years. You can access the LA Times article here. To look at the abstract of the scientific study, click here. The authors of the article inlcude Noam Greenbaum, Tessa M. Harden, Victor R. Baker, John Weisheit, Michael L. Cline, Naomi Porat, Rafi Halevi and John Dohrenwend.

Work done by Dr. Victor Baker at the University of Arizona, uncovered deposits of silt and driftwood located high up the bank along a stretch of river known as the "Moab daily," about 8 miles upstream from town. Here they found evidence for 44 large floods occurring in the last 2,000+ years. These were not merely high water year floods, but were exceptionally large floods, that likely resulted from rain on snow events. Of the 44 floods detected, 34 of them exceeded the accepted 100-year-flood level and a whopping 26 of them dwarfed 500-year-floods. Two massive paleofloods were higher than scenarios that engineers and planners now use to prepare for flood disasters. The discharge for these floods is estimated at over 300,000 cubic feet per second (cfs). To compare, the largest estimated modern flood at Lee's Ferry, Arizona was in 1884 and is estimated to have crested at 125,000 cfs.

Baker said that Glen Canyon Dam is ill prepared to handle floods such as these, should they occur today."It’s not something theoretical,” said Noam Greenbaum of the University of Haifa in Israel, the lead author of the study. “What we are actually documenting are the natural floods.

Amid placid days of drought, risks of massive floods may loom for the Colorado River
All of this research dances around the question of the purpose, sensibility and utility of building dams on wildly fluctuating river systems like the Colorado. The dams were originally conceived as a way to protect people from devastating floods and to save water for times of need during droughts. In this respect they have worked marvelously. However, others have pointed out that there are some negatives to this manner of river management. It is obvious that when the dams were conceived and constructed, all of the negatives were minimized and the positives were accentuated. As time has moved on since the era of dam building, some of the negatives are popping up like an unwanted house guest.

As a geologist, I naturally tend to look at both sides of an argument before leaning one way or the other. I understand for example, that these dams have allowed our southwestern culture to thrive. Yet, is it a good thing that 35 million people are dependent on a river that fluctuates between scorching drought and (now) humungous floods? The dams have clearly done what we wanted them to do. But at the same time, our knowledge of the rivers' inherent nature was virtually non-existent at the time the dams were conceived and built. Do we need to rethink dams on the Colorado River?

One observation I cannot escape is that the dams are piling up sediment for which there is no obvious, easy or inexpensive solution. In the long-term, dams on sediment rich rivers is a really bad idea. I don't know how you can continue to have 35 million people (and increasing), dependent on a system of water delivery that was conceived in the hydrologic 'dark ages.' To me, it doesn't make sense and I know that the detriments of the dams will only come into clearer focus as our science and technology reveal the wild character of the river.

“Nature is variable,” Baker said in the LA Times article. "The Southwest has suffered in the wake of recent droughts, but the long-term history of the region suggests that can change quickly. Ignoring Mother Nature is not too smart,” Baker concluded.

Greenbaum points to the uncertainty of the future and hopes to seek out more long-term flood records along the river. “During the last 2,000 years, the climate changed a lot. It was maybe sometimes wetter, different periods were dryer,” he said. None of this was really known in 1922 when the Colorado River Compact was ceremoniously signed in Santa Fe.

Sharlot Hall, forever the First Lady of Arizona said it best in 1906 i the last stanza of her incredibly prescient poem, "Song of the Colorado":

O ye that would hedge and bind me — 
remembering whence I came! 
I, that was, and was mighty, 
ere your race had breath or name!  
Play with your dreams in the sunshine — 
delve and toil and plot — 
Yet I keep the way of my will to the sea, 
when ye and your race  are not!   

Sharlot Hall, 1906

How did she know? As they say, may you live in interesting times!

Tuesday, June 17, 2014

Earth From Space - An Incredible PBS Production About the Importance of Satellites in Understanding Our Planet

John G. forwarded a link to me about a PBS special on NOVA called Earth From Space. I watched it and was very impressed! Even at 1 hour and 53 minutes, the information contained in this video is remarkable. I found it interesting that funding for NOVA is provided by David Koch. Koch would seem to be a man bent on supporting those who routinely deny the importance of science in our political institutions. I'm still scratching my head on that one.

In this video you will understand why funding for NASA and the satellites it operates is crucial to understanding complex and dynamic earth systems. The program makes the point that without the long-term collection of data and the phenomenal way that "invisible" bands of light can be captured by satellites, so many of the predictive benefits that we now take for granted would not be possible. We are seeing our planet deeper and with new eyes.

In this show, you will understand the role of plankton in creating the oxygen we breathe and how lake sediments in the Sahara Desert help to fertilize the Amazon rainforest. Satellites show that three million lightning strikes occur on Earth each day and how ice that is formed in Antarctica helps to drive Earth's ocean currents and climate.

Check it out. The imagery is superb and the story is compelling.