{{unreferenced|date=February 2017}} The '''Pivka Basin''' or the '''Pivka Valley''', also simply '''Pivka''', is a varied [[Drainage basin|basin]] in southwestern [[Slovenia]], lying between high [[Dinaric Alps|Dinaric]] [[plateau]]s, the [[Karst Plateau]], and the [[Brkini Hills]]. It covers an area of {{convert|160|km2}}. To the northwest, it is bordered by [[Nanos (plateau)|Mt. Nanos]], to the north, by [[Hrušica (plateau)|Hrušica]], to the east by the [[Javornik Hills]] and [[Snežnik|Mt. Snežnik]], and to the west by the lower [[Slavina Plain]] and [[Tabor Hills]]. The lower part of the basin between Nanos and the [[Postojna Gate]] is known as the '''Lower Pivka Basin''', and the upper part between [[Prestranek]] and [[Snežnik (settlement)|Snežnik]] as the '''Upper Pivka Basin'''.
==Hydrology== The [[Black Sea]]–[[Adriatic Sea]] [[drainage divide]] crosses the Pivka Basin, with the majority of water flowing to the [[Ljubljanica]] Basin. The [[Pivka (river)|Pivka River]] with its tributary the Nanoščica sinks in [[Postojna Cave]]. Part of the water flows to the [[Lokva River]], which sinks below [[Predjama Castle]], merges with the sinking rivers Belščica, Stranske Ponikve, and Šmihelske Ponikve, and flows into the sources of the [[Vipava (river)|Vipava River]]. The Rakuljšica and some smaller creeks, tributaries of the [[Reka (river)|Reka River]], run on the southern edge of the basin, below [[Sajevče]].
In the Upper Pivka Basin, there is a vertical [[bifurcation lake|bifurcation]], with the surface waters running to the Black Sea Basin, and the underground waters to the Adriatic Sea Basin. The bottom of the basin, which is sometimes considered a [[karst field]], has an elevation of {{convert|500|to|600|m|abbr=on}}. The lowest point of the basin ({{convert|464|m|abbr=on|disp=or}}) is at the Lokva [[ponor]] below [[Predjama Castle]].
==Climate== The natural and social influences of continental and littoral Slovenia intertwine in the Pivka Basin. Three climate types mix here: the [[Mediterranean climate|Mediterranean]], [[continental climate|continental]], and, higher at the edge, [[mountain climate]]s.
==Natural and cultural landscape== The houses feature elements of the Inner Carniolan and Littoral types. After the stabilisation of Austria's land borders, Pivka administratively belonged to [[Duchy of Carniola|Carniola]], and ecclesiastically, except for short interruptions, to the [[Diocese of Trieste]]. From 1918 to 1943, it belonged to Italy (the [[Trieste Province]]), and after World War II to Yugoslavia, where it was part of Slovenia.
The bottom of the Lower Pivka Basin is composed of impervious [[flysch]] bedrock, which at [[Razdrto, Postojna|Razdrto]] continues into the flysch [[Vipava Valley]]. On the slightly rolling small plains along the Pivka and the Nanoščica, there are [[wet meadow]]s, and small fields are found on the surrounding gentle rounded slopes. Settlements lie in elevated places among the [[alluvial plain]]s. The location of villages was mainly determined by the agricultural orientation of the population because the settlements are connected to land that can be farmed.
[[Image:GradKalec1.jpg|thumb|[[Kalec Castle]] near [[Zagorje, Pivka|Zagorja]], Pivka Basin]] The largest settlement is [[Postojna]], located at the entrance to the Postojna Gate, and on the opposite side lies Razdrto, which played a key role in transportation in the past. The Upper Pivka Basin and its upper margins, closing the basin from all sides, consists of [[Cretaceous limestone]]. The large karst field has a level bottom that is often flooded, traversed by the [[Pivka (river)|Pivka River]], along which there is a higher level terrace with numerous [[sinkhole]]s and larger basins with flat bottoms. When the level of karst water, which is always close below the surface, rises, the Pivka starts to flood near [[Zagorje, Pivka|Zagorje]]. Floods occur along the Pivka, and the Pivka Lakes in depressions, among which the largest are [[Lake Palčje]], [[Lake Petelinje]], [[Lake Parje]], and [[Lake Drskovče]]. The bottom of the Upper Pivka Basin is covered by a thin layer of [[eluvium]]. Higher-elevation parts have thin soil, suitable only for pasturing sheep or goats. The slopes are mostly covered by forest, primarily intentionally planted [[Pinus nigra|Austrian pine]], [[spruce]], and [[Larix decidua|larch]]. The settlements in the Upper Pivka Basin are most dense along the western side of the basin. They lie next to flat basins filled with more recent deposits between Pivka and [[Šembije]] in the south, next to more open fields in the broader part of the basin between Pivka and Rakitnik in the north, and next to more or less extensive [[uvala]]s of the border part of the basin. The employment and supply centre of the Upper Pivka Basin is [[Pivka]]. The development of Pivka was most influenced by its location between two administrative, economic, and cultural areas. Despite their important transport location, the settlements in the Pivka Basin have not significantly developed. This is still only an area people pass through. The most important economic activities are [[forestry]], [[wood processing]] and food processing, transport, tourism, livestock and poultry, and more recently sheep farming.
{{Pivka}}
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[[Category:Municipality of Pivka]] [[Category:Landforms of Inner Carniola]] [[Category:Structural basins of Slovenia]]