estavelle

plural estavelles

1. geographyA hole that may function as an ephemeral spring or a sinkhole, depending on hydrological conditions.

   Furthermore, the filling and emptying should occur via an estavelle, or ephemeral spring, and there should be no surface water inlet or outlet.

   2012 Summer/Haf, Gareth Farr, “Water environment”, in Natur Cymru: A Review of Wildlife in Wales, page 44

   2 more examples

   The water pressure within the earth can force a swallow hole to become a spring and vice versa. These reversible sinks, which geologists call by the French geologic term estavelle, change their direction of flow (swallow or discharge) based on fluctuations in the water table.

   2002, Sandra Friend, Sinkholes, page 35

   Depending upon the position of the groundwater level and hydrological conditions on the surface, an estavelle can function at one time as an intermittent spring and at another as a ponor (swallowhole).

   2004, Petar Milanovic, Water Resources Engineering in Karst, page 23