The leadership within the American Association for the Advancement of Science (AAAS) decided on March 18 that it is no longer necessary for scientists to continue collecting data regarding the warming of Earth’s oceans and atmosphere. In a series of interviews, the AAAS explained that the work of linking global warming to greenhouse gas emissions is done, and the best use of a scientist’s time and resources is to help society to cope with the impacts of global climate change. Explaining that the evidence was tested empirically, this was the appropriate response for the science collective to make (3 percent of this collective remains skeptical).
The important point I wish to share with the reader is that communities have never been properly prepared for climate disruptions. Droughts and floods have raged for millions of years without causing billions of dollars in damage to human communities, that is, until we decided to build permanent structures in inappropriate places, or with inadequate engineering standards. Since adapting to drought is always in the news these days, let’s take a look at the other extreme of the the water cycle—floods.
It is in our capacity to do the right thing in regards to climate adaptation. For example, Moab made the right choice when it came to moving the Atlas tailings pile to higher ground. One of the reasons why this toxic pile is being moved is because the facility was built in the 10,000-year floodplain, according to the U.S. Geological Survey (and others). Its 2005 study concluded that the peak flow of a “probable maximum flood” is at least 300,000 cubic feet per second (cfs).
Ironically, once the pile and its toxins have been removed from the floodplain, the Moab community is contemplating the future development of this site for various kinds of infrastructure. This proposed action essentially suggests that our community is not going to respond appropriately to the impacts of climate after all. If you study the proposed development scheme of our soon-to-be-reclaimed uranium waste pile, the 100-year floodplain will not be developed, but the 500-year (and above) floodplain will be developed.
It would be helpful to determine what the volume is for a 100-year flood event on the Colorado River and how long ago did such a flood last rage through through Moab? This is important information to have because the 100-year flood is the criteria that insurance companies and planning commissions usually base their rules and regulations upon.
According to a recent model prepared by the Bureau of Reclamation (paper in preparation) the answer to that question is the flood of 1884, which was also the year that Moab was originally mapped and platted for future development. The volume of that flood was successfully measured at Loma, Colorado at 125,000 cfs. We do not know what the flow of the Dolores River was in 1884, however it would be safe to say it was at least 10,000 cfs. So the flow through Moab was approximately 135,000 cfs in 1884.
A 100-year flood did not occur in the 20th century, but we had some big ones and many of us got to experience their impacts first hand. The biggest flood of the 20th century was in 1921 and the gage at Loma estimated the Colorado River peaked at 81,000 cfs. The Cisco gage above the Dewey Bridge was not operational that year, so the flow from the Dolores River is again unknown.
The other big floods of the 20th century were as follows: 1914 – 65,600 cfs; 1917 – 73,200 cfs; 1928 – 62,200 cfs; 1941 – 63,400 cfs; 1957 – 63,400 cfs; 1983 – 65,500; 1984 – 69,500 cfs. Incidentally, the summer flood of 1957 invaded the edges of the construction site for the uranium processing mill.
Another important point of reference to consider about the 1884 flood was the total volume of water that this snowmelt produced between the months of April and July, which was calculated by the Bureau of Reclamation to be approximately 30 million acre-feet. When Hoover Dam was brand new in 1935, it took 7 years to fill the reservoir to the brim (Lake Mead). The 1884 flood would have filled Lake Mead in just one summer. Obviously, a discussion about dam failure in the Colorado River basin is another climate-adaption feature worthy of our consideration; dam failure would essentially double the peak discharge of the flooding event.
For Moab, statistically speaking, the 100-year Colorado River flood is overdue by 30 years. It is highly likely that a 100-year flood will arrive sooner, rather than later. Unfortunately, it is difficult to predict when the 500, 1,000 or 5,000-year flood event will occur. Hopefully the tailings pile will be moved out of harm’s way before such an event occurs. Although adapting to climate change is imperative, as the AAAS advises, the truth is we have never adapted our infrastructure to match the power of nature, and our management plans are based more on luck than empirical data. Adapting to climate does not mean repairing buildings, bridges and dams for the rest of our existence. It means revising our laws and regulations to reflect reality so that people will stay alive, happy, and prosperous.