Karst Hydrology and Chemical Contamination
Ground-water flow in karst aquifers is very different from flow in granular or fractured aquifers. arst ground-water flow is often turbulent within discrete conduits that are convergent in their upper reaches and may be divergent in their very lower reaches, simulating the flow pattern of surface water streams that are dendritic or trellised but with discharge to one or more springs. ignificant precipitation events tend to flood karst aquifers quickly, causing a rapid rise in the potentiometric surface that may flood older, higher levels which discharge to a different set of springs. he epikarstic zone in karst terranes stores and directs infiltrating water down discrete percolation points. hemical contamination may be fed directly to a karst aquifer via overland flow to a sinkhole with little or no attenuation and may contaminate downgradient wells, springs, and sinkholes within a few hours or a few days. ontaminants may also become temporarily stored in the epikarstic zone for eventual release to the aquifer. lood pulses may flush the contaminants to cause transiently higher levels of contamination in the aquifer and discharge points. he convergent nature of flow in karst aquifers may result in contaminants becoming concentrated in conduits. nce contaminants have reached the subsurface conduits, they are likely to be rapidly transported to spring outlets. raditional aquifer remediation techniques for contaminated aquifers are less applicable to karst aquifers.
Field, M. Karst Hydrology and Chemical Contamination. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-93/510 (NTIS PB94135134).