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HARIDUSTEADUSED Tallinna Ülikooli üliõpilaste 2015/2016. õppeaasta PARIMAD TEADUSTÖÖD / Artiklite kogumik
intrOductiOn
HyDrologiCal anD HyDrogeologiCal sTuDy of
TUHALA kARST AREA
TUHALA KARSTIALA HÜDROLOOGILINE JA HÜDROGEOLOOGILINE UURING
Karsti ed carbonate aquifers may provide an abundant source of good quality groundwater (Smart, Worthington, 2004; Stevanovič, 2015). It has been estimated, that up to 25% of global population relies on the groundwater derived from karsti ed aquifers (Ford, Williams, 2007). However, they typically feature highly heterogenic hydrogeological properties and temporal variability of hydrodynamics, rendering their characterization and sustainable implementation challenging (Ford, Williams, 2007; Goldscheider et al., 2007; Ravbar, 2013).
e Silurian-Ordovician aquifer system, composed of diverse carbonate rocks, is an important source for potable water in the northern half of Estonia’s mainland and on the western islands. e aquifer system hosts, among many other shallow aquifers, the Tuhala karst area (TKA), known primarily for the peculiar over owing perennial spring, the Witch’s Well (WW). e TKA is located in the Kata vil- lage, Harju County and covers approximately 188 ha. e karst system of TKA has developed in the lower course of the Tuhala River, where a layer of deposits of the last glaciation overlies the outcrop- ping Upper-Ordovician Kõrgessaare and Saunja Formation limestones.
e humic rich water of the Tuhala river sinks into and ows through the TKA karst system and dis- charges again in the Veetõusme and the WW spring groups, situated 1-1.2 km northeast. e TKA karst system is hosted by the shallow Nabala-Rakvere aquifer, o en the only source of potable water for the households of the rural area. Consequently, it is important to gain insights into how the Tu- hala River a ects the quality of the abstracted groundwater in the region. Furthermore, the area has repeatedly fallen in the potential outreach of planned economic developments, thus has frequently been the focal point of many disputes. In order to identify the appropriate measures for the sustain- able management of such karsti ed shallow aquifers, the current study was planned to contribute to the understanding of the hydrodynamic and hydraulic operation speci cs of the TKA karst system.
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