A long series of thermo-saline logging has been carried out in wells drilled through the Mesozoic carbonate aquifèr from which the sulfur hypothermal springs of S. Cesarea Terme issue.The logging conducted at various timings (i-e. periodically, rapidly sequenced. synchronized with tides and sea conditions),over about 10 years, provided valuable data on the thermal and hydrological regimen of the area. In particular for the inshore zone, both isotherm and thermal gradient trends could be determinated. and a close identifìcation of preferential levels through which groundwaters discharge takes place was possible.In fact, flow velocity measurements made by the point diluition method. showed a mostly impervious aquifer except for eviden fissured through which low-verocity discharge ( 5-22 cm/day)takes place. When the sea is low and calm, all levels are influenced by sulfur waters except for the uppermost unconfined zone; when the sea is rough. also owing to the low permeability of the aquifer. a barrier effect against groundwater flow is triggered. Since. groundwater is prevented from discharging, it tends to reach deeper permeable levels.thus markedly altering the hydrological and thermal regimen of the deeper sulfur waters. The lithological character of aquifèrs and their low permeability are confirmed by 222Rn contents (normally l0-15 pCi/l). groundwater reaching 200 pCi/l only at levels where water starts becoming hot. This phenomenon.as supported by all investigations including those on sulfides, occurs only at temperatures exceeding 23'C. Therefore, according to the above tnvestigation. the S. Cesarea springs represent a unique hydraulic model. matching real hydrodynamic situations occurring when surrounding conditions change.
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|Titolo:||Systematic Hydrogeological Study of Hypothermal Spring (S. Cesarea Terme, Apulia), Italy|
|Data di pubblicazione:||1995|
|Appare nelle tipologie:||1.1 Articolo in rivista|