Part 2-Conservation, Management, Ethics: Veni-Karst Hydrology 121 Section A-Identifying and Protecting Cave Resources
Karst Hydrology: Protecting and Restoring Caves and Their Hydrologic Systems GeorgeVeni
Cavers tend to be conscientious. We try to tread softly through passages to limit our impact. We clean up and restore caves that have been impacted by others. We fight to preserve and protect caves and their contents from outside impacts like urbanization. We work to improve our restoration and protection methods, and, through vehicles like this book, share that information as much as possible. Many of the adverse Many orthe adverse impacts a cave may suffer and the means to prevent impacts a cave may or alleviate them are determined by the cave's hydrology. This chapter suffer and the means provides hydrologic information and guidelines to assist cavers in protect- ing and restoring caves. It teaches the basics of how caves forn1 and how to prevent or water moves through caves and their surrounding landscapes. The chapter alleviate them are also examines common hydrologic problems and impacts on caves, and determined by the what problems can be solved by individual and group actions. cave's hydrology. The following sections are meant to reach cavers of all experience levels. References are cited for those wanting details. Specific recommendations are included, but the focus is on general principles to help guide cavers through situations that cannot be covered within this chapter.
The Basics of Karst Hydrology
How Water Enters, Moves Through, and Exits Caves The movement of water through caves is closely tied to the question of how caves form. Moore and Sullivan (1997) provide a good basic over- view, while White (1988), Ford and Williams (1989), and Klimchouk and others (2000) offer highly detailed information. Gillieson (1996) offers less detail but more emphasis on cave management. Despite their wide variety of origins, caves or cave areas can be classi- fied in one of three groups: carbonate, evaporite, and pseudo karst (Figure 1). Caves in carbonate rocks form primarily in limestone, but some also occur in dolomite and marble. Caves in evaporite rocks usually form in gypsum but also in halite in exceptionally arid climates. Caves in both carbonate and evaporite rocks form primarily by water dissolving away the bedrock. The landscapes where such solutional processes are dominant are called karst. It is beyond the scope of this brief chapter to discuss all cave types in detail. Limestone caves will be emphasized since they are the most common. The typical limestone cave begins to form where water enters the rock along a fracture or bedding plane and slowly flows downward and laterally until discharged from a spring at a lower elevation. While pure water has little ability to dissolve limestone, water entering the ground is charged with carbon dioxide from the atmosphere and soil to form carbonic acid. Over millennia, the weak acid enlarges fractures and bedding planes. As the openings become larger, water drains more efficiently. These increasing 122 Cave Conservation and Restoration
Pseudokarst volumes of water then enlarge the openings at faster rales. This process George Yen; self-accelerates. Eventually, one flow path toward the spring dominates the local drainage pattern and captures flows from smaller channels. When it Caves and karst-like becomes large enough for human exploration, we call that conduit a cave. features that do not form In the more common situation, a cave map looks like a branching surface primarilyby the stream. The tips of the hydrologic network typically include fractures, dissolution of the rock sinkholes, and swallets that capture surface water and route it underground. are called pseudokarst. In the subsurface, each branch flows downstream to join other branches, Several types of eventually fonning limbs and then the trunk of the underground drainage pseudokarst feafures network which discharges from a spring (angular and curvilinear passages, occur. Major types Figure I). include the following: Geologic and hydrologic factors often prevent the development of such • Sea Caves. Formed ideal flow systems, which usually occur in relatively flat-lying, highly- where waves pound on fractured rocks that sit atop relatively impermeable rocks. cliffsand preferentially Local geologic factors frequently affect cave development. Low fracture enlarge fractures, frequency and/or continuation of the limestone deep below spring levels zones of softer rock, or result in cave networks that extend deep below the water table. Caves in areas where wave dipping rocks may branch asymmetrically, capturing most waler from the action is concentrated. updip direction. Figure 1 shows some other examples of how hydrogeologic factors that (Cootinued 00 ",xl page! create a cave relate to the cave's shape.
Braided or anastomotic passage patterns indicate slow or ponded conditions. Rectilinear mazes may suggest development by flooding or seepage through a caproek. Figure 1. A summary Ramiform and spongework patterns, such as in Carlsbad Caverns, did chart of how cave not form epigenically by water flowing down from the surface, but morphology reflects hypogenically by rising hydrogen sulfide gas mixing with groundwater hydrogeologic origin to form sulfuric acid, \vhich in turn dissolved the limestone to create (from Palmer 1991). caves.
TYPE OF RECHARGE
VIA KARST DEPRESSIONS DIFFUSE HYPOGENIC
SINKHOLES SINKING STREAMS INTO POROUS (LIMITED DISCHARGE IGREAT DISCHARGE THROUGH SANDSTONE SOLUBLE ROCK FLUCTUATION) FLUCTUATIONI DISSOLUTION 8'1' ACIDS OF DEEP-SEATED SOURCE OR SINGLE PASSAGES AND BY COOliNG OF THERMAl BRANCHWORKS CRUDE 6A/\NCHWOAKS. MOST CAVES ENLARGED WATER (USUALLY SEVERAL LEVELS) USUAlLY WITH THE FURTHER ElY RECHARGE MOST CAVES FORMED BY & SINGLE PASSAGES FOLLOWING FEATURES FROM OTHER SOURCES MIXING AT DEPTH SUPERIMPOSED:
00 w ~ ~\~-~ ~ ,/f!; >- ~"< i ~\ >- ~ /IA ; ~ ISOLATED FISSURES in ANGULAR FISSURES, \ AND RUDI"'ENTARY NETWORKS, 0 PASSAGES IRREGULAR NETWORKS FISSlJHES. NETWORKS II: NETWORKS SINGLE PASSAGES, FISSURES 0 00 PROFILE: z --=" "- " '. u. ~ 0 ~< .--- w ..... -'i IJf -/?}t.~ "z ~ !~1 "->- J~ ~ .\ >- 0 I / SHAF'T ANO CANYON RAMIFORM CAVE'S, W "m CURVILINEAR ANASTOMOSES. COMPlEXES,lNTEASTRATAl RARE SINGLE-PASSAGE /\NO >- SPONGEWORK Z PASSAGES ANASlOMOTIC MAZES SOLUTION ANASTOMOTIC CAVES « PROFILE: Z ~ :E :l 0 z0 0 < .' ..••~~.. '. .. ~i•. ~ ''J( ,". .~' ~ • • w ~~ •• ~ ", . ~ ~ RUDIMENTARY RUDIMENTARY RAMIFORM & SPONGE WORK SPONGEWOAK SPONGEWORK BRANCHWORKS " SPONGEWORK CAVES Part 2-Conservation, Management, Ethics: Veni-Karst Hydrology 123
Beyond the Cave: Water in the Drainage Basin (Con,nued) For most of the 20th century, scientists argued whether caves form above, below, or at the water table, or even whether \vater tables actually exist in • Tectonic Caves. Humanly enterable karst. \Ve now know that caves form in all of those situations, and that karst fractures that occur water tables do exist. Caves are integral parts of karst aquifers and are a where large sections part of an interconnected series of voids that transmit water down through of bedrock separate, the vadose zone (the area above the water table) and into the phreatic zone such as by one side (the water-saturated area below the water table), and eventually out of the slumping down a spring. Aquifers are reservoirs of water held underground in whatever hillside or valley. voids exist in the rocks and soil. In karst, these voids make up complicated networks of fractures, bedding planes, some pore spaces, and of course, • Talus Caves. caves. Humanlyenterable The area that feeds all water into a stream, spring, or cave is called the spaces that occur beneath and within drainage basin. Valley ridgelines define the drainage basin boundaries for piles of large fallen surface streams. All water that enters the basins must eventually flow rocks. through these streams. Groundwater drainage basins do not always con- form to the boundaries of surface basins. Karst groundwater basins arc • Suffosion Features, notorious for crossing below surface basin boundaries, but they still These include caves function by similar principles. Rather than surface water flowing down a and sinkhole-like topographic surface, groundwater flows down from "ridges" to "valleys" or depressions that form troughs in the water table where flow is concentrated. Significant cave by the localized streams often flow along these troughs. downward movement Subsurface flow converges on large conduits because of their greater of fine, unconsolidated material through or ability to transmit water. Even hypogenic caves, which form independently below locally denser or of water entering the ground from the surface, capture local flO\v paths better-cemented from the surface to form drips, domes, pools, and streams. Figure 2 material. illustrates how water that seeps or floods into sinkholes, fractures, and sinking streams flows down troughs in the water table to merge into single • Volcanic Pseudo- large cave streams, and discharges from the same spring, It should there- karst. Lava tubes fore be clear that caves, plus the rate, volume, and quality of water that are the most extensive flows through them, and the materials carried in the water, directly reflect type of volcanic the conditions and activities on the surface in the cave's drainage basin. pseudokarst. Lava tubes form where Cave Chemistry and Speleothems molten lava drains from beneath a cooling, Some of the water which enters caves is responsible for creating solidifying lava flow. speleothems. Hill and Forti (1997) provide the authoritative review of (See lava tube caves, speleothems and cave minerals. While there are over 250 minerals and page 133.) dozens of types and subtypes of speleothem forms, calcite and gypsum speleothems are by far the most common and are those discussed here. While these features As water moves through a rock, it dissolves minerals along the way and form by radically carries the ions in solution. At some point, the water may become super- different processes than saturated with respect to a particular mineral, meaning it is carrying more karst caves, they often of the dissolved material than it can hold, and so it deposits the minerals, bear hydrologic similarities such as The amount of carbon dioxide (C0 ) in the water primarily determines 2 turbulent flow through how much dissolved calcite the water will hold, and where and at what rate large conduits and little the calcite will be released. The more CO~ in the water, the more calcite it to no filtration of can keep in solution. Calcite is most commonly deposited where sufficient contaminants, Much of CO is released from the water to result in calcite supersaturation. Typical 2 the information locations include where water emerges from the limestone wall, releasing presented in this chapter carbon dioxide into the cave atmosphere which has far less CO~, or where will also apply to turbulence releases CO~ by splashing the water onto a stalagmiie or running pseudokarst areas, it over a flowstone slop-e or rimstone dam. Evaporation also plays a part in the deposition of calcite but is far more important in the development of gypsum speleothems and is their usual cause of supersaturation. While calcite does not dissolve in pure water, gypsum is soluble in water and thus more chemically vulnerable to changes in cave environmcnts. Consequcntly, gypsum speleothems form primarily in dry passages that no longer contain active streams. 124 Cave Conservation and Restoration
LEGEND INDEX TO GROUNDWATER BASINS I'I'ltentiomelric; (water ••. eI) _000- ~ AND SUB-BASINS ~ COnwil1te", •• ,20Ille!
Fklw route and tonlIooroce ilS cleletmioed by dye !raO!!Sand N poteobomelr'l;lXIOlours HogMe-
I \ \ .1
i r- ;' '. . - .••. -i '.I •. 'o,
MAJOR SPRINGS SH Sandhouse Cave E Echo River T Tumhole S Sly> ••n SC Sand Cave G GrealOoyx CG Cot!onGin P Pike u.ooo ••••• C CedarSink M Mill Hole
Figure 2. Map of the The ages of speleothems are frequently misunderstood. Ages are often Turnhole Spring estimated based on an assumed constant growth rate. which is rarely the groundwater drainage case. Each speleothem is different, reflecting the unique water chemistry basin and some and flow rate along each flow path, as well as soil and climatic factors on smaller adjacent the surface. All of these factors change with time, and thus change the basins (from Quinlan conditions of speleothem development. and Ewers 1989). Generally, the larger speleothems are the oldest, but not always; they may just reflect rapid mineral deposition, while nearby small speleothems, which form by slower deposition rates, may in fact be much older. Under certain unusual conditions, speleothems can grow up to several centimeters Part 2-Cave Conservation, Management, Ethics: Veni-Karst Hydrology 125 within a year. Typically, several centimeters of growth requires hundreds to thousands afyears. Thus, any impacts on speleothems are effectively permanent.
The Sensitivity of Karst Systems to Contamination and Modification Among the various Among the various types of aquifers around the world, karst aquifers are the most sensitive to groundwater contamination and the most easily types of aquifers impacted by modification of the surface landscape. Drew and Hotzl (1999) around the world, describe these impacts in detail. Caves, solutionally enlarged fractures, and karst aquifers are the other voids create highly permeable features so that the volume of water most sensitive to discharged from karst wells and springs are the greatest volumes on record. groundwater However, this same permeability also allows easy access for pollutants. contamination and Karst aquifers can respond so quickly to surface activities, that in many ways, they function as direct extensions of the surface landscapes. The the most easily im- conduit systems in karst allow for the rapid transmission of contaminants pacted by modifica- with effectively no filtration. Studies repeatedly show that when contami- tion of the surface nants are present in karst areas, they invariably reach and adversely impact landscape. their aquifers. The close hydrologic connection with the surface also makes karst aquifers sensitive to physical changes in the landscape. Increased flooding, decreased runoff, sedimentation, and erosion on the surface are often mirrored by changes in caves and the general behavior of the karst aquifer. Well pumping and artificial recharge of water can also dramatically change aquifer conditions on a scale and rate that is much greater than in other groundwater systems. Few effective engineering solutions have been developed to prevent many of the problems which are unique to karst. It is therefore vital that people living and working in karst arcas avoid creating problems in the first place. Watson and others (1997) and Veni and DuChene (200 I) offer broad, yet concise guidelines for the protection and management of karst areas.
Common Hydrologic Problems: How Cavers Can Avoid, Find, and Resolve Them
The many types of activities that threaten caves and karst areas fall into two groups: those resulting from pollution and those caused by physical modification of the karst system. This section addresses the most common problems and provides guidance on what cavers can do to resolve them, beginning with problems most directly relatcd to cavers and ending with those over which cavers have no direct control. Hydrologic issues related to cave restoration activities are discussed at the end of this section.
Groundwater Pollution Exploration Pollution "Pack it in. Pack it out." This motto has frequently been used by cavers to state that we should carry our trash out of caves. Spent batteries or carbide are especially hazardous to groundwater. They should be removed in leak-proof containers and disposed of properly. Too many stories are still told of how bags or bottles of spent carbide ruptured or exploded. Let's do the job right and use appropriate containers.
Human \Vaste. Unfortunately, urine and feces are sometimes deposited in caves. In hydrologically inactive caves, these wastes should instead be packaged and removed whether or not the caves are decorated with speleothems. Certain areas in such caves tend to become restrooms which accumulate wastes. Even ifburied in sediments, the wastes may migrate 126 Cave Conservation and Restoration
into the local groundwater. In a concentrated amount they could prove harmful. (See human waste, pages 35, 71, and 276; also see packaging waste, page 269.) In hydrologically active caves, while unappealing, relatively small amounts of human wastes left in caves will get nushed out of the system or mixed with animal wastes washed in from the surface and will cause no significant impact. Ifcamping in or near a cave entrance and packing out wastes is not an option, cavers should dig latrines as far from the entrance as practical in deep, vegetated soil where biological activity will more rapidly decompose the wastes. Latrines should not be placed where they may be rapidly eroded by surface runoff. If possible, they should be placed down slope from springs, sinkholes, or cave entrances.
Contaminated water Bathing and \Vashing Gear. Bathing and washing camping and caving that soaks into cave equipment in hydrologically active caves is not a problem from a general groundwater contamination standpoint. However, in hydrologically inactive sediments should caves with only isolated pools, contact with the pools should be avoided. not be discounted as Cavers may use them as untreated water supplies and could become ill. harmless; many Additionally, the pools could be biologically significant and harmed by species burrow and caver-introduced bacteria. (See pools page 74.) lay eggs in the Tracer Tests. Dye tracing has been used by cavers to delineate drainage sediments and can basins and hydrologic connections between caves, sinkholes, and springs. be injured or killed However, as increasing numbers of tracer tests are conducted, state and by acids or bleach. municipal authorities are increasiflgly regulating their use. Cavers could be fined for tracer testing without an appropriate permit. One important reason for regulation is to reduce cross-contamination, where one tracer test unknowingly picks up dye from a second test and produces an inaccurate interpretation. Since tracer tests are important in decisions on land, water, and waste management, undiscovered interference in the results could have major repercussions. While most dyes have low toxicities, some are more hazardous and should not be used if they may reach a spring or well used for drinking water. Cavers who wish to dye trace should tirst check their state regulations, cheek carefully for other possible traces in the area, inform potentially affected people of their trace, and learn the proper methods, amounts;and types of dyes prior to injecting them into the karst. Eckenfelder (1996) provides guidance on designing and implementing sound tracer studies.
Restoration Pollution Like some pollutants resulting from exploration, pollutants produced during the restoration of caves are not usually produced in sufficient volume to harm an aquifer's groundwater quality. However, these pollut- ants can severely impact water quality in localized areas within caves to the detriment of cave fauna and cavers who may use that water tor drinking. Contaminated water that soaks into cave sediments should not be discounted as harmless; many species burrow and lay eggs in the sediments and can be injured or killed by acids or bleach running off walls and speleothems after removing graffiti and algae. Too much water flowing into normally dry passages can be equally destructive to cave ecosystems. The use of chemicals in caves should be avoided or minimized. If applied, all chemicals should be thoroughly rinsed and diluted with water. Clean towels and sponges should be placed immediately downslope of restored surfaces to capture as much runoff as possible. Runoff containing chemicals should be placed into water-tight sealable boltles, then removed from the cave and deposited into a municipal sewage system for proper treatment. (See anthropogenic chemicals, page 57.) Part 2-Conservation, Management, Ethics: Veni-Karst Hydrology 127
Rural Pollution Caves located in rural areas have the best chance to avoid human-produced contaminants. While such contaminants do occur in rural areas, they do not usually occur in the volume and severity found in urban and industrial areas. The drainage basins of many rural caves include areas of light to inten- sive agriculture. Extensive activities, such as livestock grazing, result in higher than natural bacteriological contamination of caves (Figure 3). Such operations cannot be easily relocated, but they pose far less of an impact than runoff from feedlots or barnyards. Caves located in rural areas have the Landowner Assistance. Many rural landowners recognize the hazard to best chance to avoid their own drinking water supplies and do not place septic systems and human-produced barnyards near caves and sinkholes. Cavers can assist landowners by contaminants. guiding such activities away from surface drainages that feed into caves or from areas and sinkholes directly above caves that are identified during cave mapping. Cavers can especially help by discouraging owners from dumping trash into caves and sinkholes and by cleaning up existing dumps. In some areas, municipal or regional agencies may ofTer funding or other support to volunteers and owners who clean up such sites. (See sinkhole cleanout, page 381.) Residents ofmral areas should be made aware of the special sensitivity of karst to pollution. Cavers can offer publications and photographs showing how pesticides and fertilizers used in some agriculture and pollutants in trash dumps may contaminate karst aquifers. Rural residents' standard water purification method of sedimentation in storage tanks, natural die-ofT of some pathogens, and chlorine treatment of any remaining organisms may not adequately cleanse the water.
Urban and Industrial Pollution Urban and industrial areas produce pollutants in the greatest volume, variety, and toxicity, and they survive the longest in the environment. While it is tempting to suggest plugging caves and sinkholes, or at least diverting drainage away from them to prevent groundwater contamination, While it is tempting such actions will often prove ineffective. Polluted runoff can enter karst to suggest plugging aquifers in greatest volume via large entrances or sinkholes, but significant pollution can also flow underground through small sinkholes, solutionally caves and sinkholes, enlarged fractures, and other less obvious pathways. Protection of indi- or at least diverting vidual karst features alone is not a sound method for aquifer protection. drainage away from them to prevent Pollution Prevention Strategies. Protection of aquifer water quality groundwater con- requires excluding contaminants from the karst area and preventing those present from entering the surface water or groundwater. Prevention is not tamination, such actions will often prove ineffective.
Figure 3. Livestock in a sinkhole pond. 128 Cave Conservation and Restoration
easy. Sedimentation and filtration basins are among a group of measures called best management practices used to capture and remove contaminants. (See best management practices, page 34; also see current best practices, page 17.) However, it is important to remember that best does not mean effective. Their efficiency varies widely according to the specific method used and the pollutant treated, with common contaminant removal rates less than 40% (for example, Tenney and others 1995). [n many cases, the Veni (1999) proposed a strategy for assessing potential impacts in karst best solution is to and found where there are insufficient data for definitive assessments, purchase critical limiting impervious cover to 15% of the area ufthe drainage basin should preserve groundwater quality. This percentage correlates to the level of caves and drainage urbanization where a broad suite of studies found that significant ecological areas for protection and water quality degradation begins to occur (Schueler 1994). from urbanization. Pollution Prcycntion Coalitions. The water quality problems which exist in urban karst areas are well beyond the ability of most cavers to solve individually. As groups, cavers should learn to work cooperatively with landowners and regulatory agencies, yet also be prepared for adversarial relationships with regulators who may lack the authority or impetus for certain protective actions without sufficient public outcry. In many cases, the best solution is to purchase critical caves and drainage areas for protection from urbanization. Examples exist throughout the country of volunteer groups pushing major land purchases made by local, state, and federal agencies, by cave conservancies and organizations like The Nature Conservancy, and even by businesses looking to develop good public images and tax write-offs for conservation casements. In working with these groups, cavers should be careful to not oversell their technical knowledge and expertise if they don't have an actual specialist in their group. However, cavers should be equally careful not to undersell their perspective. Most regulators and many non karst geologists lack cavers' important information and knowledge from inside the aquifer. Maps, photos, and videos demonstrating how water and contaminants move through caves can be worth far more to regulators and judges than the opinions of well-paid consultants who never venture underground into a karst aquifer. (See photodocumentation, page 204.) Land purchases will not be practical in many situations, in which case cavers should work with agencies and organizations to educate the public In working with and promote sound voluntary stewardship of the karst by public and private these groups, cavers landowners. Conservation easements, tax relief incentives, and support for should be careful to ecologically sound yet profitable land uses can also be promoted to reduce not oversell their impacts in karst areas and drainage basins. technical knowledge and expertise if they Hydrologic Modifications don't have an actual Exploration Modifications specialist in their To further exploration, cavers have drained sumps, diverted streams, group. However, notched rimstone dams, and built dams, among other actions that hydro- logically changed caves. The possible consequences of each action are too cavers should be numerous to individually discuss and rely too much on specific local equally careful not conditions beyond the scope of this chapter. to undersell their Most hydrologic changes from exploration tend to be short-term and thus perspective. probably of no significant impact. The impacts of long-term or permanent changes should be closely considered before implementation, and tested, if possible, with temporary modifications that produce the same effects. Distinguishing between short-term and long-term modifications will need to be done case-by-case. The impacts of hydrologic modifications from exploration can be addressed as two general groups. Part 2-Conservation, Management, Ethics: Veni-Karst Hydrology 129 I Hydrologic Impacts. One type of impact is the hydrologic change in the cave and aquifer. Water in cave streams flows to springs and/or wells and may be increased lor decreased by dams or diversion. Removal of natural dams (breakdown, rimstone, or otherwise) may result in turbid (muddy) flow for some time as sediment once trapped behind the dam is washed out and affects the stream's use as a water supply. Speleothem growth and development may change in affected parts of the cave. Dam construction would have opposite effects, increasing flooding and sedimentation of upstream areas, and causing some sediment erosion in downstream arcas. I Biological Impacts. Hydrologic modifications can also adversely affect a cave's ecosystem~ Penn anent draining of sumps or flooding of passages may isolate populations and dismpt feeding and reproductive behavior. Changes in water, depth, temperature, turbidity, velocity, /lood levels, and flood frequency may also harm ecosystems adapted to specific conditions. (See conservervation don'ts, page 35.) I Water Chemistry Modifications Discounting the introduction of contaminants into a cave and the hydro- logic modificatiops discussed above, a significant hydrochemical change occurs in some show caves which divert water from one part of the cave to another to "reactivate" inactive speleothems or provide constant flow to waterfalls. The idea is that since water from the cave is used, speleothems The effects of will grow and the cave will be kept "natural." The problem is that the modifications on the chemistry of waters throughout a cave may vary dramatically. The water land surface provide diverted to reactivate a speleothem, especially if diverted from a tlowing additional examples stream, may be chemically undersaturated and hence would begin to dissolve the spel<~othem. Certainly, wet speleothems are more sparkly and of how closely caves attractive than dry ones, but dry speleothems are also natural features of and karst aquifers caves. I are tied to activities , on the surface. Surface Modifications The effects of modifications on the land surface provide additional examples of how closely caves and karst aquifers are tied to activities on the surface. I Vegetation and Soil Loss. Vegetation and soil are important to preserving the reservoirs of shallow groundwater that sustain speleothem growth and pools in the caves below. While vegetation tends to use water stored in the soil, it also holds the soil in place. protecting it from erosion and high evaporation of its water. Significant loss of vegetation invariably leads to the loss of soil, soil moisture, and moisture in the caves. The chemical changes in the water are less predictable. Less soil and vegetation means less CO~.The resulting changes in water now rates into the cave and reaction rates of tile water with the limestone may prompt, halt; or have no measurable effect on speleothem growth. Eroded soil also often ends up deposited in and sometimes plugs caves and sinkholes. I Increases in Surface \Vater Runoff. Decreases in soil and vegetation on the surface result in greater and faster runoff of rainwater. Impervious covers like concrete and asphalt allow no infiltration or storage, and all rainwater runs off into streams. Increased runoff results in higher and more frequent flooding of streams. If the streams lead underground, caves may be flooded beyond their normal levels, destroying habitat for cave species adapted to dry conditions in those areas, dissolving speleothems, depositing sediments in some areas, and eroding old sediment deposits in other areas that might hold paleontologically or archaeologically significant materials. Gypsum speleothems. even above the new tlood levels,' could potentially be dissolved by tlood-induced increases in humid air flow. 130 Cave Conservation and Restoration
Quarries and l\lines. Quarrying is the complete removal ofthe rock for use, such as the removal of limestone for building stone, concrete, and gravel. Mining is the selective removal of material, such as minerals and fuels, from within the larger bedrock mass. Quarrying occurs by digging huge open pits, While Ihe quarrying while mining can be through open pits, tunneling, or well drilling. or mining away of a While the quarrying or mining away of a cave arc obvious impacts on cave are obvious cave hydrology, major adverse impacts are possible in caves not directly impacts on cave touched by the operations. The most common problem is dewatering or hydrology, major lowering of the natural watcr table, which can drain cave streams, stop springflows, and cause sinkholes to collapse (Figure 4). Another severe adverse impacts are problem is groundwater contamination, especially from acids and metal- possible in caves not laced waters discharging into streams or the ground from mining activities. directly touched by the operations. Dams. Dams are built to hold water, which is extremely difficult to accomplish in karst areas. Caves and sinkholes below and near dam sites are plugged with concrete to keep the water from leaking out of the reservoir. Nonetheless, water levels and flooding in caves upstream and downstream of the dam will increase because most of the caves and karst features will not be found and plugged. Those above the dam will be inundated if they are located beneath the reservoir; caves further away and at higher elevations may have their lower levels flooded by the elevated water table produced by the dammed lake. Caves and springs downstream of the dam will see a marked increase in flow from the leakage that will invariably occur despite the best efforts to block it.
Regulations. All of the surface modifications described above are likely beyond the ability of individual cavers to affect. Fortunately, tougher regulations and more in-depth research prior to the permitting of such operations are decreasing the frequency and intensity of these problems. Cavers working with the permitting process may help regulators with the important measures listed here.
Steer operations away from the most sensitive areas. Enact tough protective measures if sensitive areas cannot be avoided. Perhaps limit already permitted activities ifnew information shows the potential for severe impacts that were previously unknown.
As discussed in the above section on pollution, conservation actions that preserve, purchase, or consider the entire drainage basin will be most
Figure 4. Sinkholes may collapse from several factors that modify their hydrol- ogy. Groundwater contamination can result if a collapse breached sewage and other pollutant-bearing pipelines. Part 2-Conservation, Management, Ethics: Veni-Karst Hydrology 131 effective in protecting caves and aquifers from activities that modify large sections of the karst surface.
Hydrology and Cave Restoration
Restoration actiJities have mostly beneficial hydrologic impacts on caves; adverse impacts are few and minor. The removal of unnatural rock and sediment piles is' important to restoring natural water and sediment flow through caves. Trash removal improves water quality and ecological integrity. Concentrated sprays of water are effective in cleaning many cave surfaces. (See pressurized water for restoration, page 397.) Unfortunately, bleach is commonly used in water sprays to remove algae in show caves. Fungi have been'cleaned from gypsum crusts with a bleach mist solution, followed by rinsing with water the next day (Rogers 1995). Until new methods are available, bleach should be minimized in concentration, volume, and area because it indiscriminately kills cave organisms. (See bleach, page 349; also see lamp flora control, page 343.) Research is also needed for bette~ ways of cleaning gypsum speleothems. Spray cleaning dissolves gypsum and frequent cleaning may prove harmful. (See gypsum Restoration cleaning, page419.) activities have Restoration activities must be planned to avoid adverse impacts from the mostly benefi-cial use of inappropriate chemicals and materials, or appropriate materials used hydrologic impacts in inappropriate ways. Other chapters in this book describe cave-safe on caves. Adverse supplies and methods in detail. Luckily, the quantity of materials and the impacts are few and areas of restoration are generally small; improper techniques and supplies will usually not have adverse cave-wide hydrologic impacts, and there will mmor. be time for corrective measures. In hydrologically active caves, there is probably no substantial difference in impact by using cave water instead of noncave water to clean speleothems, so long as the water source is unpolluted and unchlorinated. (See sources for restoration water, page 393.) Water brought into a cave that is significantly hotter or colder than the cave's temperature should be allowed to equalize with the cave if rare species may be present. The short- term and small-range application of the water should make any differences in chemistry inconsequential, especially if the restoration water is captured after use and removed from the cave. Water from within a cave may be the most convenient! but use it with caution if few pools exist and are slow to replenish. Filtering the used water for placement back into the pools is an option assuming'chemicals have not been added to the water and the pool has no rare organisms and was not completely drained. (See filtration and pool restoration,lpage 415.) Filtered restoration water could be used for additional washing if water is scarce. If the cave is dry and has a sensitive microbiological community, water from surface streams could introduce new microorganisms and should not be used. (See isolated pools, page 73; see uncontaminated pools, page 74; also see water choices, page 338.)
Summary
The hydrologic protection and management of caves requires consideration of a broad range 'of factors. They necessitate understanding of small features within diVes to karst aquifer drainage basins that extend far beyond a cave's known limits. Small-scale considerations typically involve aesthetics and biological management. Large scale factors include smaI1- scale concerns, but mainly involve issues of groundwater quality and quantity, plus land use management. As urbanization, mining, and other intensive uses of karst areas increase, 132 Cave Conservation and Restoration
cavers will need to extend their efforts in cave restoration and protection to include the landscapes in which they occur. They will need to coordinate with and lobby regulatory agencies for general land resource protection. It is vital for cavers to work with other groups to purchase and preserve karst drainage areas in perpetuity as the only assured means of conserving our fragile and unique underground resources.
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