Relative importance and chemical effects of diffuse and focused recharge in an eogenetic karst aquifer: an example from the unconfined upper Floridan aquifer, USAImportance relative et effets sur la qualité de l’eau associés à une recharge diffuse et ponctuelle d’un aquifère karstique de type éogène: l’exemple de l’aquifère supérieur libre de Floride, Etats Unis d’AmériqueLa importancia relativa y los efectos químicos de la recarga difusa o focalizada en un acuífero kárstico cogenético: un ejemplo del acuífero superior no confinado de Florida, EEUUImportância relativa e efeitos químicos da recarga pontual e difusa num aquífero cársico eogenético: O exemplo do aquífero livre superior Floridan, EUA扩散和集中补给对表生喀斯特含水层的相对重要性和化学效应 : 美国佛罗里达潜水层实例

Karst aquifer studies often focus on allogenic water inputs and large conduit flow. However, diffuse recharge can be significant, particularly in unconfined eogenetic karst aquifers that retain high matrix permeability. This study examines an unconfined region of the upper Floridan aquifer (USA) that hosts a sinking stream, its resurgence, and a large conduit system. Daily diffuse recharge was approximated using a water-budget method and ranged from 17% of precipitation during a low precipitation year to >53% during the highest precipitation year, illustrating the highly variable nature of diffuse recharge in this region. The total allogenic input via the sinking stream over the 5 years of the study was significantly larger than the volume of diffuse recharge. However, only about 2% of the allogenic recharge flows from the conduit into the surrounding aquifer. That flow is restricted to storm events when hydraulic heads in the conduits exceed those in the surrounding aquifer. The estimated volume of dissolution is similar for allogenic recharge and diffuse recharge to the unconfined region surrounding the conduits, but dissolution from the diffuse recharge is distributed over a larger area than dissolution from allogenic recharge. These results exemplify how recharge type impacts flow and water–rock interactions in eogenetic karst aquifers.