Myth or Fact: Are Sinkholes Caused by Farming Irrigation?
Sink holes seem to be an increasing problem in Florida and throughout the country, and some people blame farming irrigation. But is it true, or are the other factors causing sinkholes to appear?
Sinkholes caused $1.4 billion in damage from 2006 to 2009 in Florida alone. Costs are continuing to rise due to the increasing incidence of sinkholes. Due to its geology and climate, Florida is one of the most susceptible states to sinkhole damage in the United States.
With such astronomical costs associated with sinkholes, many people are wondering what causes sinkholes and if activities such as farming irrigation are accelerating their occurrence.
Read on to find out more about sinkholes, what causes them, and what you can do to help prevent them.
How Do Sinkholes Form?
A sinkhole is most commonly formed when land is underlain by particular types of rock. These rocks are prone to dissolution by the acid found in rainwater as it circulates down through the soil and into the rock. The main types of rock involved in sinkholes include limestone, carbonate rock, and salt beds.
Sinkholes can take thousands of years to develop to the point of collapse. Groundwater initially dissolves small portions of the rock, creating small caverns. These caverns are enlarged by water that percolates down through the ground, and the sand and clay soil above the caverns begin to sink.
Once the underlying rock has been dissolved by rainwater, it is termed "karst." Collapse finally occurs when the caverns get too large and can no longer support the overlying land.
Sinkholes vary greatly in size. Some can be as small as a few feet wide and deep, while others can span hundreds of acres and reach a depth of over one hundred feet.
What Causes Sinkholes?
In the most general sense, water is what causes sinkholes. Sinkhole development, however, is accelerated by a number of natural and man-made causes.
Tropical Storms and Heavy Rainfall
Tropical storms and heavy rainfall have such a profound influence on sinkholes that there is a dedicated "sinkhole season." In Florida, this season begins in early spring and tends to coincide with hurricane season when rainfall is at its highest.
When areas underlain by karst receive significant rainfall, the sudden weight of the heavy rain causes the karst to lose stability and collapse.
Too little water can also have an impact on the occurrence of sinkholes. When moist soil fills the karst, it becomes relatively stable. However, drought causes the water within the karst to withdraw and the karst becomes less stable.
Heavy rainfall following a significant drought creates prime conditions for sinkholes because of the destabilized karst and the sudden influx of rainwater into the cavities.
Land development has had a significant impact on the rising amount of sinkholes. In fact, developed land is eleven times more at risk for sinkholes than undeveloped land.
The primary reason for the increased incidence of sinkholes on developed land is due to the added weight of new buildings and houses, as well as paved roads and concrete sidewalks on land that is already unstable.
In addition to the added weight, land development causes water that typically would have percolated down through the soil in a relatively even distribution pattern and diverts it to concentrated infiltration points. Land development also comes with underground water pipes which can leak and further erode the karst.
Growing populations require increasing amounts of water in order for their homes and businesses to be inhabitable. To meet that demand, water must be pumped out of the water table that previously stabilized the karst. The Villages in Southwest Florida saw their water use increase from 63 million gallons a year in 1991 to 12.4 billion gallons a year in 2017.
Florida's main source of drinking water is the Floridian Aquifer -- groundwater. As demand increases, the water table shrinks and destabilizes the karst leading to more sinkholes.
But it's not just drinking water depleting the Aquifer. Golf course and lawn maintenance require tremendous amounts of water to irrigate the grass and keep it a vibrant green. Golf courses also have retention ponds which tend to leak and erode karst as well.
Agriculture is frequently cited as a major reason for sinkholes.
Sinkholes can occur in agricultural areas as a result of irrigation methods used to prevent crops from freezing that quickly deplete groundwater levels. One of the most common methods of irrigation during frost-freeze events is sprinkler irrigation due to its ease of use and low cost. Sprinkler irrigation works by spraying crops with water, which then forms a layer of ice and protects the crops from freezing temperatures.
Sprinkler irrigation requires large quantities of water to be pumped from aquifers in a short amount of time. This irrigation method has led to water shortages due to increased use of water by farmers. The karst in the rapidly depleting aquifer is destabilized as a result, and studies have shown a significant relationship between sprinkler irrigation, frost-freeze events, and sinkholes.
Homeowners and business owners can protect themselves from sinkholes through the purchase of insurance that covers sinkhole damage, and by having the land on which their property sits surveyed for potential sinkholes. These options are also good for those in commercial agriculture, but there are also tools and practices you can implement in order to reduce the likelihood of sinkholes occurring on your land.
One major change you can make in your farming methods is to utilize raised beds. Raised beds for crops are less likely to cause sinkholes and can be easily shaped through the use of the SuperBedder Bed Shaper.
Special equipment, such as this Raised Bed Plastic Mulch Layer, is also available to make their maintenance less labor intensive and drive down costs.
Don't Let Sinkholes Bury Your Business
Sinkholes are a dangerous and expensive risk for anyone living or working in Florida, but they can be especially devastating for commercial farmers. One sinkhole has the potential to destroy your whole harvest.
While there are a variety of factors that contribute to the incidence of sinkholes, you still need to do everything you can to prevent your business from falling victim to one.
We can help you outfit your business with the best equipment that will help you stop sinkholes. Contact us today!