Florea Lee J, Vacher H L
Depaertment of Geology, University of South Florida, Tampa, FL 33620, USA.
Ground Water. 2007 Jul-Aug;45(4):439-46. doi: 10.1111/j.1745-6584.2007.00309.x.
Eogenetic karst lies geographically and temporally close to the depositional environment of limestone in warm marine water at low latitude, in areas marked by midafternoon thunderstorms during a summer rainy season. Spring hydrographs from such an environment in north-central Florida are characterized by smooth, months-long, seasonal maxima. The passage of Hurricanes Frances and Jeanne in September 2004 over three field locations shows how the eogenetic karst of the Upper Floridan Aquifer responds to unequivocal recharge events. Hydrographs at wells in the High Springs area, Rainbow Springs, and at Morris, Briar, and Bat Caves all responded promptly with a similar drawn-out rise to a maximum that extended long into the winter dry season. The timing indicates that the typical hydrograph of eogenetic karst is not the short-term fluctuations of springs in epigenic, telogenetic karst, or the smoothed response to all the summer thunderstorms, but rather the protracted response of the system to rainfall that exceeds a threshold. The similarity of cave and noncave hydrographs indicates distributed autogenic recharge and a free communication between secondary porosity and permeable matrix-both of which differ from the hydrology of epigenic, telogenetic karst. At Briar Cave, drip rates lagged behind the water table rise, suggesting that recharge was delivered by fractures, which control the cave's morphology. At High Springs, hydrographs at the Santa Fe River and a submerged conduit apparently connected to it show sharp maxima after the storms, unlike the other cave hydrographs. Our interpretation is that the caves, in general, are discontinuous.
早期岩溶在地理和时间上与低纬度温暖海水中石灰岩的沉积环境相近，位于夏季雨季午后常有雷暴的地区。佛罗里达州中北部这种环境下的泉水流量过程线的特点是平滑、持续数月的季节性最大值。2004年9月飓风弗朗西斯和珍妮经过三个野外地点，显示了佛罗里达上层含水层的早期岩溶对明确的补给事件的响应。高泉地区、彩虹泉以及莫里斯、布莱尔和蝙蝠洞的井的流量过程线都迅速做出了类似的缓慢上升反应，达到最大值并一直持续到冬季旱季。这一时间表明，早期岩溶的典型流量过程线不是后生、晚期岩溶中泉水的短期波动，也不是对所有夏季雷暴的平滑响应，而是系统对超过阈值的降雨的长期响应。洞穴和非洞穴流量过程线的相似性表明存在分布式自生补给以及次生孔隙与可渗透基质之间的自由连通——这两者都与后生、晚期岩溶的水文情况不同。在布莱尔洞，滴速滞后于地下水位上升，这表明补给是通过控制洞穴形态的裂缝进行的。在高泉，圣菲河和与之明显相连的一条地下管道的流量过程线在风暴后显示出急剧的最大值，这与其他洞穴流量过程线不同。我们的解释是，一般来说，洞穴是不连续的。
