Ljubljana Marshes (Ljubljansko barje) is situated in the south-western area of the Ljubljana Basin. The area is 163 km², which represents 0.8% of the territory of the Republic of Slovenia. Ljubljansko barje has characteristics of a polje. The Barje area is a tectonic collapse from two million years ago, formed at the junction of the Alpine and Dinaric area with tectonic subsidence from the transition of the Pliocene to the Pleistocene.
Partly from the end of the last Ice Age, the area of today's Barje was covered with a shallow lake that gradually turned into a swamp. 4500 years BC, the first farmers were settled in the area. In the shallow flood plains around the lake, small settlements were set up – stilt house settlements. In 1875, the first remains were discovered at Ig. Today, there are 40 known locations of former stilt houses. On 27 June 2011, this area was listed on the UNESCO World Heritage list alongside other prehistoric stilt houses in the wider Alpine region.
The karst river Ljubljanica flows from several karst springs on the southern and western edges of Barje. The torrential tributaries of Iška and Gradaščica have created alluvial fans. The bottom of the Barje is therefore the lowest in the middle and rises towards the edges. The Ljubljanica River has a very small fall in its 20 km long flow: the bottom of the riverbed at Verd is 285 meters, and in Ljubljana, it is only about a meter lower, at 284 meters.
The Flood Lake and the 2010 Event
The consequence of this low inclination are regular floods that, at the highest water level, create a flood lake of about 80 km² area. The formation of the flood lake is similar to that of the intermittent Lake Cerknica. The frequency of filling and discharging of this lake, known as "Barjansko jezero," has been reduced by the completion of the Gruber river channel in 1780, which effectively lowered the risk of annual floods.
In September 2010, the area experienced exceptional flooding after heavy rains from the 17th to the 19th. During this event, the landscape became unrecognizable from the perspective of a boat. Pheasants were perched on trees rising above the water, while cats dremucked in the sun on the roofs of houses as if nothing had happened. It is precisely because of this high water potential that Plečnik's church sanctuary in Črna vas is located on the first floor.
Landscape Park and Natural Monuments
In 2008, the Ljubljana Marshes were proclaimed a landscape park. Protected areas include the Ljubljanica River, the springs of Močilnik, Retovje, and Bistra, Lake Podpeč, and several nature reserves like Mali plac and Iški morost. The area is also known for its artesian groundwater, which under pressure can easily reach the surface through simple boreholes.
Author: Boštjan Burger, University graduate geographer (Karst Department)
Literature & Sources:
* UNESCO World Heritage List: whc.unesco.org/en/list/1363
* Decree on the proclamation of the Ljubljanica riverbed as a cultural monument of national importance.