State the objective, why are we learning about springs and groundwater? What success will look like for our learners...they will be able to describe how water moves through the ground to a spring and what threats there are to the quality & quantity of the water. They will be learning what environmental factors have an impact on springs and groundwater, the importance of quality groundwater (we drink it!) and basic cave exploring guidelines. Ask students why we need to know more about groundwater and Missouri's natural resources. Set aside time each day for students to complete the "Living in Cave Country....What is Karst" project.
Review what was learned the previous day, and introduce the concept of the natural movement of water from the surface, through the subsurface and back to the surface again via a spring or well. View a spring picture and brainstorm ideas of what could change the amount or quality of groundwater. At this point make an anchor chart listing and sorting the class input. View the "Natural History" video (about 5 minutes); Revisit the anchor chart to add or delete ideas/thoughts that may have developed after viewing these materials.
Recap learning from yesterday by discussing springs and groundwater movement from rain to a spring. View the video "Caves, A Deeper Look at our Earth" (about 13 minutes).
Divide students into small groups of 2 or 3 students each. Instruct them to draw and describe a common feature of a karst area, including a 1.) groundwater source and a 2.) spring. Each drawing should be labeled and described in detail, including specific factors that influence their "watershed." Teams should use remaining time to produce and finalize their work and to rehearse a team presentation about their karst landform project.
This day is set aside for team presentations about their watershed project. Evaluation will include participation and understanding by each of the team members. In addition students can see everything first hand through one of the classroom opportunities at Fantastic Caverns.
Contributions by Ms. Crystal Chodes, Springfield Public Schools
To gauge prior understanding and knowledge, ask students to explain what they know about springs and the water coming from them. In addition, ask what might change the amount of water coming from a spring. This may include a verbal presentation, written report, or drawing.
Have students brainstorm the facts that they may already know about springs and maybe even the movement of groundwater.
The movement of rainwater down from the surface and through a cave shows the surface-subsurface connection. This water brings in nutrients for the cave animals. But it also can bring in contaminants. If we pollute the surface, we also pollute the subsurface. One way to put it: "what goes down comes up". To understand how this works, you first need to know something about karst and its problems.
Karst is where the dissolving of soluble rocks - limestone, dolomite, gypsum, or marble - plays the major role in land erosion. Karst areas have caves, springs, sinkholes and sinking streams (which flow into the ground and disappear) - the whole area resembles Swiss cheese coated with soil.
Water creates these features in soluble rock. It also uses them as conduits: entering through sinkholes, flowing underground through caves, and surfacing again at springs. A spring is the drainage point for a cave; a cave is a drained spring system. Southern Missouri contains these features and the unique environmental problems associated with them.
There are two basic ways in which water from the surface recharges groundwater in Karst areas: discrete recharge and diffuse recharge. Discrete recharge is very localized, and often involves large quantities of water that move rapidly into groundwater supplies. A storm water stream disappearing into a sinkhole is an example. Discrete recharge typically provides ineffective natural filtration and cleansing for water. In contrast, diffuse recharge involves slower moving water that seeps through soil and rock units in route to groundwater supplies.
Understanding sinkholes is another way to understand the surface-subsurface relationship in cave country. A sinkhole is a depression in the earth's surface with subsurface drainage, where water has dissolved out a drainage network through the rock. Sinkholes are the entry points for water into spring systems. Soil, organic debris, and sometimes pollutants move down through sinkholes during rainstorms. These materials are transported through underground streams, and finally resurface at springs. That's why we say in the Ozarks that whatever goes down comes back up.
To trace the movement of underground water, a harmless dye is added to water flowing into a sinkhole. Charcoal packets placed at springs can remove some of the dye from the water. If the dye is detected, then that sinkhole is one of the sources for that spring. The process is simple and direct.
A sinkhole relates to an underground stream in much the same way a surface gully relates to a surface stream. To protect the quality of water in surface streams, we must protect the quality of water in gullies. Similarly, if we are to protect the quality of water in underground streams and springs, we must protect the quality of water entering sinkholes. Figure 1 shows how a typical sinkhole plain relates to the surface in karst terrain. There are many sinkhole areas in Missouri, one large area includes Springfield.
Surface To Subsurface Pollution
Caves and the land in which they are located are closely tied together. What happens on the surface can affect caves. Therefore, groundwater pollution in cave country is a serious problem. It's often more serious than surface water pollution. Several types of groundwater pollution occur frequently. The most common is human waste (sewage), followed by industrial and hazardous waste.
All too often, poorly planned sewage systems (such as septic field systems) contaminate nearby wells and springs. Entire towns may contaminate karst groundwater systems if they discharge wastewater to surface streams that sink into the ground and feed groundwater supplies. The key to preventing these problems is sound planning with emphasis on groundwater protection. If sewage enters karst groundwater, it can seriously deplete the amount of oxygen dissolved in the water. Aquatic life suffocates without oxygen, and the water exudes offensive odors.
A case history may be helpful in understanding the sensitivity of underground streams to oxygen depletion. Hidden River Cave is a large stream cave system located in Horse Cave, Kentucky. The cave's drainage basin is a large sinkhole plain in karst terrain. The community discharged large quantities of poorly treated sewage directly into the cave stream. During the summer, terrible odors came out of the cave entrance that was in the business district of Horse Cave. The odors substantially detracted from the entire area. In addition, the cave was both a major tourist attraction and the water supply for the city of Horse Cave: neither of these uses was possible (Aley, 1981). A project costing millions of dollars was necessary to restore the groundwater quality of the region. Perhaps this historic disaster will help us prevent similar situations in Missouri karst areas.
City sewers can cause problems for groundwater in karst areas if the sewers leak. And they often do leak. Sinkhole development and land subsidence are common process in karst areas, and the processes can crack sewer lines or separate connections in the lines. Much of the sewage lost from sewer lines discharges from springs.
Many of our city sewers are old and have serious leakage problems. Some need to be replaced. Sometimes old sewers can be repaired by inserting new plastic pipes inside the old lines. New sewers need to be constructed of materials that can better withstand the effects of sinkhole collapse and land subsidence. A new sewer line crossing a sinkhole area near Horse Cave is made of a plastic pipe that has a great ability to stretch. When new sinkholes develop along this sewer line, this new pipe will stretch across the holes rather than break and dump sewage into the groundwater system.
Industrial and Hazardous Waste
This category includes everything from chemical and gasoline spills to landfills to the disposal of hazardous and radioactive wastes. The location of industrial plants is important since many factories use chemicals and other materials that can seriously degrade water quality.
Factories must have good waste disposal facilities. Where city sewers don't exist, factories sometimes use lagoons for waste disposal. Sometimes the lagoons leak into groundwater supplies and damage water quality in the region. Leaky industrial lagoons have caused serious groundwater problems near Springfield, Missouri.
Gasoline and other petroleum products are familiar to all of us. Many of these products however, are serious water pollutants. Leaking underground fuel storage tanks have ruined thousands of wells in the United States. Gasoline can readily follow the same underground routes as water. Imagine what happens when gasoline is spilled in a sinkhole. Unfortunately, it's almost impossible to remove all the gasoline once it enters the groundwater.
Even the disposal of common trash and garbage creates serious problems in karst areas. In the United States, we generate about 3.5 pounds of solid waste per person per day. At present, much of this waste goes to landfills. In karst areas, substantial volumes of water commonly move through the trash and create a liquid called landfill leachate, which routinely contains heavy metals, chemicals, and other toxic materials. This liquid seeping from a landfill also has a tremendous appetite for oxygen. When it mixes with clean groundwater supplies, the end product often is a septic spring or well which kills aquatic life and causes terrible odors.
What can we do about these problems? First, everyone needs to understand that wastes from our use of the surface can easily enter karst groundwater systems. Creating pollution benefits no one. Factories must not be located where they are likely to cause groundwater pollution - such as in areas with numerous sinkholes. Fuel storage tanks should be designed so that they don't leak. Sometimes in karst areas incinerators are a better solution for trash disposal than landfills. Groundwater pollution always results from landfills in karst areas.
In the early 1970’s Fantastic Caverns began to monitor the quality of groundwater in its underground system. The water is of high natural quality now. These conditions must be preserved for several reasons. First, the cave is a natural wonder and a major recreational and educational resource for the region. Second, the cave provides critically important habitat for cave animals - such as the Ozark cavefish and the bristly cave crayfish - which are threatened with extinction. Finally, the water in the cave stream is an indicator of the quality of water in hundreds of area wells.
As part of our Science Program, Fantastic Caverns has participated in groundwater studies in the area. These include groundwater traces to delineate, or define, the recharge area for Fantastic Caverns and nearby springs. Protecting groundwater is a major part of protecting caves, and an important part of living in cave country.