Ledavsko jezero
| Ledavsko jezero | |||||||
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| Coordinates | 46 ° 45 '2 " N , 16 ° 2' 19" O | ||||||
| Data on the structure | |||||||
| Construction time: | 1975-1979 | ||||||
| Height above valley floor: | 218 m. i. J. | ||||||
| Height of the structure crown: | 7.5 m | ||||||
| Crown length: | 750 m | ||||||
| Data on the reservoir | |||||||
| Water surface | 76 ha | ||||||
| Reservoir length | 1.5 km | ||||||
| Reservoir width | 650 m | ||||||
| Maximum depth | 3.5 m | ||||||
| Storage space | 5.6 million m³ | ||||||
| Catchment area | 105.25 km² | ||||||
| Particularities: | |||||||
The Ledavsko jezero (also Jezero Krašči ) is a flood retention basin in the municipalities of Cankova and Rogašovci in the Prekmurje region in northeastern Slovenia . The facility, built in the second half of the 1970s, dams the Ledava River in the Goričko Landscape Protection Park and was designated a Natura 2000 area as a refuge for rare animal species . Through considerable Schwebstoffeinträge silted lake increasingly.
Location and surroundings
The lake is at 218 m. i. J. in the Goričko region on the upper reaches of the Ledava , nestled between the hills Črnski breg and Žilavčev breg. The water area is divided between the villages of Krašči ( Cankova municipality ) and Ropoča ( Rogašovci municipality ). Because a large part of the lake belongs to Krašči, the name Kraško jezero, which literally means karst lake, has become commonplace and, given the tertiary lithology, is an unfortunate choice. A few hundred meters southeast of the dam is the village of Domajinci and the Ledava valley opens up to the Mur basin (Mursko polje) . The lake is part of the Raab-Őrség-Goričko trilateral nature park . The regional capital Murska Sobota is around 13 km away.
Flood protection
In the past, there were repeated widespread flooding along the Ledava, which reached catastrophic proportions in July 1972. Surveys have shown that a retention basin could save 10,000 ha of arable land from flooding and significantly reduce flood damage to another 20,000 ha. The city administration of Murska Sobota then decided in 1973 to build a reservoir with funds from the SRS water fund . After purchasing a total of 164 hectares of arable land, a 750 m long and up to 7.5 m high embankment was raised. Construction began in 1975 and ended in 1979.
The total area of those plots that are designated in the official cadastre with the land use type “lake” is 122 hectares, but the actual water area is only 76 hectares. At the maximum possible utilization of the storage area, an area of 215 hectares could be flooded, even though a municipal road would be under water. The water level line for a five-year flood (HQ5) was 220.9, that for HQ100 with 222.1 m. i. J. calculated. The storage volume was originally 5.6 million m³.
geomorphology
The catchment area of Ledavsko jezero covers a good 105 km², more than a third of which is in Austria. The area is mainly divided into agricultural areas (37.8%), forests (36.7%), meadows (12.1%) and permanent crops (3.4%). Geologically, central and upper Pliocene gravel , sands and clays dominate, the valley floor of the streams is covered by alluvial soils with sandy loam deposits .
The Ledava and its left tributary Lukaj potok bring an average of 2457 t of suspended matter into the lake each year , which has led to morphological changes in the body of water for decades. Due to siltation and silt deposits on the lake bed, both the area and the effective retention volume have decreased since 1979. The lake depth has halved since the completion of the facility. A model calculation shows that with a volume of 2.4 million m³, an average discharge of 1.26 m³ / s and an absorption capacity of the suspended matter of 79.5%, the Ledavsko jezero has a " half-life " of 93 years. That would mean that by 2072 half of its original water surface could have silted up. Although northern Prekmurje is one of the driest regions in Slovenia with annual precipitation of 800 mm, an increase in extreme rain events in the context of climate change could increase the suspended matter loads. In order to maintain the retention function, scientists from the University of Ljubljana recommend removing the sediments and taking preventive measures to reduce the entry.
Due to the siltation problem, the Ledava downstream is more and more likely to dry out.
Water quality
The Directive 2000/60 / EC (Water Framework Directive) provides for monitoring since 2003, standing waters in front with an area of over 50 hectares. Ledavsko jezero is one of 17 Slovenian lakes whose water quality has been checked in this way. The measured values from 2003 to 2006 confirm that the “heavily modified water body” has a hypertrophic (very nutrient-rich) chemical condition.
| Chemical state of water (2003-2006) | ||||||
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Phosphorus (µg / l) |
Inorganic nitrogen (µg / l) |
Translucency ø (m) |
Translucency min. (m) |
Chlorophyll ø (µg / l) |
Chlorophyll max. (µg / l) |
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| Ledavsko j. | 136 | 2194 | 0.6 | 0.4 | 70.2 | 176.2 |
| OECD criteria | ||||||
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| Trophy level |
Phosphorus (µg / l) |
Inorganic nitrogen (µg / l) |
Translucency ø (m) |
Translucency min. (m) |
Chlorophyll ø (µg / l) |
Chlorophyll max. (µg / l) |
| ultra-oligotrophic | <4 | <200 | > 12 | > 6 | <1 | <2.5 |
| oligotrophic | ˂ 10 | 200-400 | ˃ 6 | ˂ 3 | ˂ 2.5 | 8th |
| mesotrophic | 10-35 | 300-650 | 6–3 | 3-1.5 | 2.5-8 | 8-25 |
| eutrophic | 35-100 | 500-1500 | 3-1.5 | 1.5-0.7 | 8-25 | 25-75 |
| hypertrophic | > 100 | > 1500 | <1.5 | <0.7 | > 25 | > 75 |
In addition, random sample analyzes of the feeders revealed a slight exposure to pesticides and heavy metals , including metolachlor , atrazine , AOX and cadmium . As a result, algae bloom on the lake from time to time . The muddy bottom of the lake also ensures a certain abundance of fish, which was confirmed in the course of sampling to assess the ecological status. In August 2010, 2860 fish weighing 63 kg were caught in the nets at 16 collection points spread across the lake over a total period of twelve hours. The water temperature during the investigation was 23 ° C, the oxygen content 12 µg / l, which corresponds to an oxygen saturation of 146%. The pH value was slightly basic at 8.9 , the electrical conductivity was measured at 350 µS / cm.
The project “SPNU Ledave in jezera”, co-financed by the EU, was intended to help develop water management including protective measures for the upper Ledava and the reservoir, in order to contribute to the improvement of the chemical and ecological water status.
Flora and fauna
In the past few decades, an ecosystem of its own has developed on and around the lake , which is home to several rare and threatened animal species . The vegetation near the shore consists of willows and linden trees as well as cattails , sedges and rushes . The north then to the water surface land is of a wetland - habitat determined and temporarily flooded soils.
Due to these newly created habitats, a Natura 2000 area was established, which mainly includes the alluvial forest in the mouth of the Ledava. The most important protected assets are the bird and amphibian population, which should be preserved in accordance with Directive 92/43 / EEC (Fauna-Flora-Habitat Directive) . Of the 14 protected bird species found in Goričko, nine are directly or indirectly linked to Ledavsko jezero. The occasional white- tailed eagle uses the lake as well as the black stork , white stork , kingfisher and bittern for foraging. The latter two also nest in the bank area. Quail and reed warbler prefer the meadows north of the lake as a nesting and feeding place. In the riparian forests and along the Ledava also come backed shrike and black woodpecker before. In the course of several years of bird monitoring , 60 different species were counted.
The protected amphibians are the Alpine crested newt and the yellow-bellied toad . The eight amphibian species found had an average reproduction rate of 8,000 specimens per year between 2006 and 2016. Twice a year, measures to protect frogs and toads take place on the adjacent streets. Other species protected under the Habitats Directive are otters , bitterlings and lampreys , river mussels and narrow diaper snails, as well as large spring damsel , pit beetle , hermit , light and dark blue buttonhead .
tourism
In addition to flood and species protection as well as the original secondary goal of using the water for agricultural irrigation, the lake also fulfills a tourist function. 54 hectares of its total area are approved for fishing . Mainly carp , pike , catfish , chub , bream , barbel and pikeperch are fished . Seasonally, the lake is popular with windsurfers and other water sports enthusiasts. On the 6 to 8 km long nature trail Bernardina pot (after the biologist Bernard Novak) you can walk around the lake along some information boards.
According to a visitor survey using cognitive maps, Ledavsko jezero, along with Sotinski breg , Grad Castle and Bukovniško jezero, is one of the most popular sights in the Goričko Landscape Park.
Web links
Individual evidence
- ↑ a b c d e f g h Joc Triglav: Vodna infrastructure in zemliški cadastre. In: Geodetski vestnik. 56/4 (2012), pp. 674-690. Online PDF , accessed on July 4, 2018 (Slovenian).
- ↑ Ledavsko jezero. Geopedia.si, accessed July 1, 2018 (Slovenian).
- ↑ a b Zavod za Ribištvo Slovenije (ed.): Vzorčenje rib v zadrževalnikih Panonske nižine za vredotenje ekološkega stanja v skladu z Vodno direktivo (Direktiva 2000/60 / ES). Ljubljana 2010, 62 p. Online PDF ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. , accessed on July 2, 2018 (Slovenian).
- ↑ a b c d Polona Ojsteršek Zorčič & Matjaž Glavan: Dotok suspendiranih snovi v akumulacijo Ledavsko jezero. In: 26. Mišičev vodarski dan. Ljubljana 2015, pp. 144–150. Online PDF , accessed on July 4, 2018 (Slovenian).
- ↑ a b Krajinski park Goričko (ed.): Značilnosti. Information board on the south-east bank of the lake (Slovenian).
- ↑ a b c Simon Balažic, Tijana Mićić, Stansilav Bukovnik & Timotej Mišič: SPNU Ledave in Jezera. In: Miščev vodarski dan 2007. pp. 87–93. Online PDF , accessed on July 2, 2018 (Slovenian).
- ↑ a b c d Mojca Dobnikar Tehovnik (Ed.): Kakovost voda v Sloveniji. Agencija Republike Slovenije za okolje 2008, 73 pp. Online PDF , accessed on July 4, 2018 (Slovenian).
- ↑ a b c Kristjan Malačič: Ledava in Ledavsko jezero - Ptice in dvoživke. Krajinski park Goričko 2016, presentation with 27 slides. Online PDF , accessed on July 2, 2018 (Slovenian).
- ↑ Tamara Markovič: Ledavsko Lake. Gorički list, June 20, 2012, accessed July 2, 2018 (Slovenian).
- ↑ Darijan Marič: Zgodovina in predstavitev vasi Krašči. PGD Krašči, accessed on July 2, 2018 (Slovenian).
- ↑ Jana Meljo: Poročilo o delu Inštituta za vode Republike Slovenije za leto 2012. Ljubljana 2012, 44 p. Online PDF , accessed on July 5, 2018 (Slovenian).
- ↑ Petra Gostinčar, Boštjan Jerebic, Jani Kozina, Barbara Lampič, Karmen Peternelj & Jernej Tiran: Krajinski Park Goričko: Omejitve in možnosti za razvoj zavarovanega območja. In: Tatjana Kikec (ed.): 20. Zborovanje Slovenskih Geografov - Pomurje Trajnostni regionalni razvoj ob reki Muri. Murska Sobota 2009, pp. 341-353 (Slovenian). Online PDF , accessed July 3, 2018.
