When President Obama and the First Family visit Carlsbad Caverns National Park this week, it will be the first time in my memory that a sitting president visited a cave. Certainly other presidents descended into the depths of the earth to view wondrous stalactites and stalagmites, but it is hard to imagine Richard Nixon, George W. Bush, or Bill Clinton crawling through muddy caverns during their times in the Oval Office.
The President's visit provides an opportunity to expand on a national conversation on cave and karst landscapes. Karst, a term that originated in southeastern Europe, refers to the landscapes that result when soluble rock--typically limestone--dissolves slowly over time. Roughly 20% of the earth's surface is covered by these types of landscapes and about 50% of our drinking water comes from karst aquifers.
What is so unusual about karst landscapes compared to other landscape types is that there is very rapid drainage from the surface to the subsurface via conduits that form as the rock dissolves. These conduits range in size from a few millimeters to expansive spaces the size of Carlsbad Caverns. They connect with each other to form sponge-like conditions in the subsurface.
There are many problems that those that live on these landscapes face that are not regularly part of the national conversation on environmental issues, especially in the area of pollution, water management, and ground stability.
Water pollution in karst areas is of growing concern in karst regions. The interconnected nature of the subsurface means that a single pollution event can disperse harmful chemicals very quickly over vast distances. While we know that dilution can help reduce impacts, many aquifers in karst areas are in serious trouble because of regional pollution problems. In Florida, for example, nutrient pollution levels of the Floridan Aquifer, the most productive aquifer in the southeastern United States, are increasing seemingly everywhere due to the interconnected nature of the subsurface. There is concern over the long-term sustainability of many important aquifers around the world due to similar regional pollution problems. Unlike many other landscape types where water pollution is seen as a local problem, water pollution in karst landscapes leads to long-term subtle degradation of the entire aquifer.
The management of water resources is also problematic. Karst landscapes often go through boom-bust cycles that express in the form of drought and flood. The rapidly growing cities of San Antonio and Austin, which are part of the karstic Edwards Plateau, were concerned several months ago about whether or not there would be enough water for the region. Wells were going dry and many were worried that the region would need to find ways to slow growth and limit development. Recently, however, the region was impacted by severe flooding that caused extensive property damage and loss of life.
These boom/bust cycles are caused, in part, by the lack of normal surface streams in karst areas. Surface flow moves quickly to the cavernous depths and there is limited surface water in many karst regions. When droughts occur, entire regions are impacted as thirsty cities and agricultural enterprises pump their interconnected aquifers. When heavy rains come back, the lack of surface streams tends to cause regional flash floods that wreck havoc--especially in urbanized landscapes. We have not come to terms with how best to plan and manage our water resources in karst regions of the country.
Finally, ground stability is a significant issue of concern in karst regions. Sinkholes cause millions of dollars in property damage each year throughout the country. In Florida, it is very difficult to get appropriate sinkhole insurance coverage for homes. Sinkhole formation is a slow geologic process that often culminates in spectacular and sometimes deadly collapses. The collapse of a portion of the famous National Corvette Museum in Bowling Green, Kentucky, in 2014 showed us how dangerous collapses can be. We have not yet had a thorough national conversation on how we can deal with the scientific and policy issues associated with sinkholes.
Thus, as President Obama visits Carlsbad Caverns, one of the most beautiful places in the world where one can see the subsurface expression of the solution of soluble rock, it is a good time to consider how we can elevate cave and karst science within the national research agenda.
(Note, the writer is the Chairman of the Board of the National Cave and Karst Research Institute which is based in Carlsbad, New Mexico.)