If you do not know the term Karst, you should. After reading this post, I hope you will understand it better and appreciate its significance.
Karst is a deep, extensive, vital and very complex network that is being increasingly threatened. Yet, as with most things on our planet, humans are very dependent on its existence and responsible for the fate of its survival.
Karst is a type of aquifer. Karst water resources represent about 25% of the drinkable supply in the world!
The following links will provide more than adequate detail to better understand make makes karsts so special. I like this first link: Physical Geology Slides-Ground Water because it provides a nice set of photos that include karsts. This next link: Karst and the USGS (while a map of the US) provides a composite view of their erratic shape and distribution. You will find embedded global maps of karsts showing their distribution around the globe in some of the other links.
When exposed, the remains of karst can be quite magnificent. Designated a UNESCO World Heritage Site in 1992. Wulingyuan (China) is an example of karst remains. James Cameron used these Chinese towers as inspiration for scenes of the Hallelujah Mountains in Avatar.
Understanding karsts is no simple thing. I suggest you do you own research to identify the aspects of karsts that are of personal interest. Karsts exist throughout each continent. They are best represented by caves that tunnel deep into the earth and massive sinkholes that suddenly appear in cities and alongside highway systems.
Karsts are under assault. Not be alien warships in a science fiction movie but from forces more destructive – surface contaminants and depletion. The cause and effect of sinkholes is direct. As excessive groundwater is taken from these giant aquifers, there is little support for the land above. From the link: Karst Groundwater, here is the issue.
“The quality of the groundwater is dependent upon how we use the land and how well we protect the quality of groundwater recharge. An old adage is that whatever goes up comes down. In karst areas, whatever goes down, comes up–up through a cave, a spring or a well.”
The following article from Circle of Blue: Hidden Waters, Dragons in the Deep: The Freshwater Crisis in China’s Karst Regions – describes the challenge.
“For more than 20 miles, the river flows beneath the surface of the earth, coursing through dark caverns and crevices, unseen and unknown to those who live above, its precise path a mystery. It emerges again through the mouth of a second cave, Nan Dong, the South Cave. These two openings in the earth, where the Yang Liu River slips into and out of the shadows is also a fateful human dividing line, a place where China’s desperate confrontation with water scarcity, industrial modernization and pollution come into clear focus.”
This confrontation is occurring throughout the world as the demand for more and more water increases. In the state of Minnesota, the stakes are just as high. Gambling on the Karst is all about
“earthen-lined manure lagoons would hold more than seven million gallons of manure…The soil is underlain by cracked, water-soluble rock, riddled with underground tunnels and caves. That makes the region’s groundwater highly vulnerable to pollution. Depressions, known as sinkholes, can appear without warning when the underlying rock collapses. Sinkholes act like drains, whooshing water – and contaminants – into underground aquifers.
Studies of China’s southwest karst region indicate the water beneath the surface is contaminated with bacteria, chemicals and sediments that drain off the land.“
We often fail to consider how even the most fundamental development tasks can have severe and consequential damage. This link: Minimizing Karst Related Risks in Highway Construction is yet another example.
As you read more about karsts, there is a very simple thought to keep in mind. From the link: Natural and Anthropogenic Hazards in Karst Areas: An Introduction,
“their [karst] high vulnerability is further expressed by a very simple concept that is true for many other environments but probably shows its best evidence in karst. It is very easy to damage or destroy natural resources but restoration to a pristine situation is an extremely difficult and commonly impossible, task. Where some degree of remediation is possible, the economic cost is commonly very high.”
In the hidden heart of each karst,
“every action carried out at the surface may have a rapid, and potentially dangerous, effect underground.”