Sinkholes and a Disappearing Lake: Victory Lake Case Study

Abstract

Human-induced sinkhole collapse can result in drastic changes to landscape aesthetics and present challenges to land managers seeking to determine the plausibility of restoration, the amount of financial investment needed, and the long-term sustainability of tampering with karstic environments. Alteration of groundwater flow in a karstic environment expedited the formation of large sinkholes in the southern end of man-made Victory Lake, causing it to drain immediately. Soon after the lake emptied in 1986, two unsuccessful attempts were made to restore the 13 ha (32 ac) lake. The sinkholes formed in the southern basin were completely in-filled, eliminating 3 ha (8 ac) of lake basin and significantly altering the original lake morphology. Some twenty-seven years later, Victory Lake is holding some water in the shallow basin at the northern end and would primarily be classified as a marshy wetland. This study was initiated to investigate the current relationship between the groundwater and surface water at the lake's altered basin to determine the potential for it to be restored fully or partially as a recreational focal point of the Berry College campus. Over the course of one year we measured the inputs (stream flow and precipitation) and outputs (evaporation and surface water outflow) of the lake system. We were able to conclude that groundwater is not likely contributing to the lake, based on inorganic and stable isotope ( 18 O and 2 H) water chemistry analysis and the deep position of the groundwater table relative to the lake bottom. From the results of dye-tracer tests conducted in the lake, we concluded that basin water may not be escaping downward at measurable rates because of its clay bottom. Our overall water-budget analysis confirms an adequate water volume entering by rainfall and ephemeral stream inflow; nearly 90% of the water leaves Victory Lake through surface-water outflow. Water loss through evapotranspiration during spring and summer months overcomes the gain accomplished during wetter and cooler months, particularly February. Through an investigation of water level records kept for campus monitoring wells from 1998 through 2012 we confirm that the groundwater table has stabilized and the immediate threat of new sinkhole formation is minimal. Restoration of Victory Lake to its original picturesque meeting spot may be possible through creative engineering strategies and project financing. However, we question the longevity of managing a karstic environment and consider the potential risks to infrastructure, groundwater, and human health should lake bottom failure occur again on campus.

A reactivated cave system induces rapidly developing cover-collapse sinkholes in Tasmania, Australia

“…The cover-collapse sinkholes documented during this study are similar to sinkholes developed in other karst areas buried by thick Quaternary overburden deposits that have been impacted as a result of regional water table lowering. As mentioned in the Introduction, there are numerous examples of quarrying or withdrawal of water from aquifers lowering water tables and causing sinkholes to form in surrounding land, due to the removal of buoyant support for sediments or soils above the sediment/limestone contact (Kaufmann and Quinif, 2002;Parise and Pascali, 2003;Heidari et al, 2011;Khanlari et al, 2012;Jovanelly, 2014;Dell'Aringa et al, 2014;Jia et al, 2018;Pan et al, 2018). The process is well-illustrated in the review by Langer (2001, fig.…”

“…There are also numerous documented examples of anthropogenic impacts triggering rapid development of cover-collapse sinkholes. A notable example is that presented by the draining of Victory Lake in Georgia (Jovanelly, 2014). This man-made recreational lake was entirely drained by the lowering of the groundwater table by limestone quarrying: as a result cover-collapse sinkholes formed beneath the lake bed and linked the water in the lake to an existing subsurface karst aquifer, which itself was connected to the quarry, causing the lake to drain overnight (Jovanelly, 2014).…”

“…A notable example is that presented by the draining of Victory Lake in Georgia (Jovanelly, 2014). This man-made recreational lake was entirely drained by the lowering of the groundwater table by limestone quarrying: as a result cover-collapse sinkholes formed beneath the lake bed and linked the water in the lake to an existing subsurface karst aquifer, which itself was connected to the quarry, causing the lake to drain overnight (Jovanelly, 2014). Similar aquifer drawdown impacts resulting from quarry and mine operations and aquifer over-exploitation have been described in Italy (Parise and Pascali, 2003;Dell'Aringa et al, 2014), China (Jia et al, 2018;Pan et al, 2018), Iran (Heidari et al, 2011;Khanlari et al, 2012) and Belgium (Kaufmann and Quinif, 2002), amongst numerous other examples of this phenomenon in the USA and elsewhere, as reviewed by Langer (2001, p. 15-30).…”