Thaler Bach (Mur)

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Thaler Bach
Katzelbach (in the upper reaches)
Thaler Bach in the Thaler (Göstinger) Graben

Thaler Bach in the Thaler (Göstinger) Graben

Data
location Styria , Austria
River system Danube
Drain over Mühlgang  → Mur  → Drau  → Danube  → Black Sea
source South slope of the Generalkogel
47 ° 5 ′ 45 ″  N , 15 ° 19 ′ 33 ″  E
Source height 622  m above sea level A.
muzzle in Graz - Gösting in den Mühlgang Coordinates: 47 ° 5 '47 "  N , 15 ° 24' 23"  E 47 ° 5 '47 "  N , 15 ° 24' 23"  E
Mouth height 359  m above sea level A.
Height difference 263 m
Bottom slope 17 ‰
length 15.2 km
Catchment area 21.94 km²
Left tributaries Erlenbach , Winkelbach , Labgraben
Flowing lakes Thaler lake
Big cities Graz
Communities Sankt Oswald near Plankenwarth , Thal

The Thaler Bach or Thalerbach (formerly Göstingbach or Thalbach ) is a right bank tributary of the Mur in the Austrian state of Styria . Together with its natural upper course, the Katzelbach , it forms a 15-kilometer-long watercourse in the vicinity of the provincial capital Graz , which is interrupted by the artificially created Thaler See .

course

Katzelbach near Hardt after leaving the castle meadow

The Katzelbach rises in the forest a few meters below the Generalkogel in the area of ​​the western Styrian municipality of Sankt Oswald bei Plankenwarth . It first flows through the Wendlleiten and Eben settlements before entering a wide Muldental valley . The stream then runs in a south-easterly direction through grassland and from kilometer five it passes through the usable areas of the Agricultural College Grottenhof-Hardt . In the area of ​​the golf course, the stream describes a bend of approximately 90 degrees and changes its direction of flow to the north-northeast. After the football field, the stream is accompanied by a footpath and cycle path at the edge of the forest and after 8.7 kilometers it feeds the popular Thaler See recreational area .

The outflow of the lake is formed by the Thaler Bach, which after a short run takes the Erlenbach on the left and then passes the Graz city ​​limits. Together with the Göstinger or Thaler Graben, the stream forms a striking valley between Madersberg , Frauenkogel and Annaberg on one side and the Plabutsch on the other. The Thalerseestraße (L331) and the state cycle route R39 run along the stream . Before reaching Schloss Gösting , the Thaler Bach steps out into the Grazer Feld before it merges with the Mühlgang .

Hydrogeology

The Göstinger Graben, which is a breakthrough in the rock of the Graz Paleozoic with an unbalanced relief, is of hydrogeological importance . Josef Zötl observed an increased water flow in the lower reaches of the Thaler Bach already in 1954, which could not be explained by the few above-ground feeders from the Thaler basin and the side ditches. The geologist expressed the assumption of underground tributaries, which could be confirmed a few years later by water level and temperature measurements. At the beginning of the 1960s, the water of several house wells sunk in the creek and hillside debris showed significant temperature differences between each other and with the creek water. The fluctuations were particularly great for those wells that are rooted in a channel deeply cut from the Paleozoic Era, which runs down from the Annaberg (ruin mountain) on the northern side of the valley. The subterranean tributaries must therefore come from fissures and strata sources , such as those found in the rennet ditch.

Natural and cultural landscape

Mountain stream character in the upper Thaler Graben

Along the watercourse, the watercourse the most important in the conservation area Western mountains and hills of Graz represents (LSG-29), there are three small-scale reserves. In the district of Thal-Eben a species-rich wetland biotope with alder break forest covering 12.3 hectares was designated as a nature reserve in 1991. A few hundred meters before the confluence with the Thaler See there is a biotope of the Niederungsbach type , which is considered to be of local importance with its hornbeam population . Further downstream, the Thaler Bach in a wooded section of the river at the beginning of the Thaler Graben has the character of a mountain stream .

The Thaler Bach is the responsibility of the Federal Hydraulic Engineering Administration (BWV) and carries a certain risk of flooding , especially on its last three kilometers . When there is a flood, the Mühlgang cannot absorb the stream, which is why even a 30- year flood (HQ 30 ) leads to large-scale flooding in the densely populated area. According to the modeling, these areas amount to 59.4 hectares and remain almost the same up to HQ 300 . The discharge at the estuary was calculated to be 28.3 (HQ 30 ), 40 (HQ 100 ) and 50.6 m³ / s for the various scenarios . Three retention basins (RHB) in the catchment area of ​​the stream are to prevent the danger. One of them is the Thaler See itself, the diversion of which can be regulated by a weir , another was completed in 2018 on the Erlenbach feeder near Oberthal Castle . The RHB Schlosswiese near Harterschlössel had already started working in 1992. In front of the confluence with the Thaler See there is also a “multifunctional forecourt” for debris and sedimentation of suspended matter .

Web links

Commons : Thaler Bach  - Collection of images, videos and audio files

Individual evidence

  1. ↑ Digital Atlas of Styria: Waters & Water Information. State of Styria , accessed April 30, 2020 .
  2. ↑ Extract from the digital Steiermark (Katzelbach) river index. State of Styria , accessed April 30, 2020 .
  3. ↑ Extract from the digital Styrian body of water index (Thaler Bach). State of Styria , accessed April 30, 2020 .
  4. ↑ BMLFUW (ed.) : List of areas of the Austrian river basins: Mur area. In: Contributions to Austria's Hydrography Issue No. 60, Vienna 2011, p. 77. PDF download , accessed on April 20, 2020.
  5. ^ Josef Zötl: The hydrogeological conditions in the basin of Thal near Graz. In: Contributions to a hydrogeology of Styria. Issue 7, Graz 1954, pp. 28–35.
  6. ^ Johann G. Haditsch: Report on a hydrogeological survey of the Steinkogel-Frauenkogel train north-west of Graz. In: Styrian contributions to hydrogeology , year 1963/64, issue 15/16, Graz 1964, pp. 155–174.
  7. ↑ NSG 56c - wetland biotope in Thal-Eben. State of Styria , accessed April 30, 2020 .
  8. ↑ a b Local development concept 5.0 including local development plan. Decision document of the market community Thal , TDC, Premstätten 2016. Online PDF , accessed on April 30, 2020.
  9. ↑ Landscape protection area No. 29. (PDF) State of Styria , accessed on April 30, 2020 .
  10. ↑ BMLFUW (ed.): Flood risk management plan. Risk area Graz-Gösting 6032. Vienna 2015. Online PDF , accessed on April 30, 2020.
  11. ↑ Erlenbach: Completion of the flood protection. State of Styria , June 2018, accessed April 30, 2020 .