Seasonal lakes of Pivka

Lake Palčje is the largest among the Pivka seasonal lakes.
Top image: high water in December, after the autumn rains; bottom image: empty area in autumn, two months earlier.

The Pivka seasonal lakes are a group of 17 seasonal lakes; the best-known are Lake Petelinje and Lake Palčje, which is the biggest of them at about 1.9 square kilometres (0.73 sq mi).^[1][2] They are all located in Pivka Basin, Inner Carniola, Slovenia.^[1] Lake Jeredovce, the northernmost lake, is in Municipality of Postojna, 10 of them (Krajnikov dol, Lake Petelinje, Lake Radohovo, Lake Klenik, Lake Palčje, Lake Parje, Big and Little Lake Drskovče, and Big and Little Lake Zagorje) are in Municipality of Pivka and the southernmost 6 (Kljun Pond, Lake Kalec, Lake behind Kalec (Veliki dol), Lake Bač, Lake Lan, and Lake Šembije) are in the Municipality of Ilirska Bistrica, all of them are located at elevations between 549 metres (1,801 ft) and 570 metres (1,870 ft).^[2] There are also two areas (polje) that are only inundated during intense floods, so they are not officially considered among the Pivka seasonal lakes.

The lakes are located on a rocky terrace in the Upper Pivka Basin at the foothills of the Javornik Hills, rising above the Pivka riverbed. The terrace is dotted with a number of depressions with flat bottoms and sharp transitions at the banks, deep enough to reach the level of groundwater fluctuation. Thus, they are inundated after periods of stronger precipitation (late autumn and spring).^[3]