Cross-formational rising groundwater at an artesian karstic basin: The Ayalon Saline Anomaly, Israel

Amos Frumkin*, Haim Gvirtzman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

It is proposed that a geothermal artesian karstic system at the central part of the Yarkon-Taninim aquifer creates the 'Ayalon Saline Anomaly' (ASA), whose mechanism has been under debate for several decades. A 4-year-long detailed groundwater monitoring was carried out at 68 new shallow boreholes in the Ayalon region, accompanied by a comprehensive survey of karstic voids. Results indicate the rising of warm-brackish groundwater through highly permeable swarms of karstic shafts, serving as an outflow of the artesian geothermal system. The ASA area contains 'hot spots', where groundwater contrasts with 'normal' water hundreds of meters away. The ASA temperature reaches 30°C (∼5°C warmer than its surroundings), chloride concentration reaches 528 mg/l (50-100 mg/l in the surrounding), H2S concentration reaches 5.6 mg/l (zero all around) and pH value is 7.0 (compared with 7.8 around). Subsequently, the hydrothermal water flows laterally of at the watertable horizon through horizontal conduits, mixing with 'normal' fresh water which had circulated at shallow depth. Following rainy seasons, maximal watertable rise is observed in the ASA compared to its surroundings. Regional hydrogeology considerations suggest that the replenishment area for the ASA water is at the Samaria Mountains, east of the ASA. The water circulates to a great depth while flowing westward, and a cross-formational upward flow is then favored close the upper sub-aquifer's confinement border.

Original languageAmerican English
Pages (from-to)316-333
Number of pages18
JournalJournal of Hydrology
Volume318
Issue number1-4
DOIs
StatePublished - 1 Mar 2006

Keywords

  • Confined karst
  • Groundwater
  • HS
  • Maze caves
  • Rising water
  • Yarkon-Taninim aquifer

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