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| Titel |
Natural hazards in Slovene karst areas: Flood risk areas in the Upper Pivka valley |
| VerfasserIn |
N. Ravbar, G. Kovačič |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250020296
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| Zusammenfassung |
| An overview of exceptional natural processes or natural hazards from the human perspective
in Slovene karst areas is made. Some types of natural hazards are typical for karst due to the
process of karstification and resulting geomorphological and hydrological characteristics of
karst landscapes (presence of voids within the rock, absence of superficial flow and presence
of specific karst groundwater flow system), while the others occur evenly in all types
of landscapes. However, their impact is different in karst as it is in the non-karst
landscapes. Examples of particular phenomenon or events, their frequency of occurrence,
expansion and caused damage are presented. Special emphasis is laid on high waters in
karst poljes, shallow karst areas or contact karst, where flooding emerges due to
the raise of karst groundwater table as a consequence of intensive precipitation or
snowmelt. Flooding in karst can also appear due to insufficient swallow capacities of the
underground channels, which are not capable of conducting surpluses of inflowing
water. In opposite to flash floods, the karst floods are more predictable, since they
usually occur in the same areas to the same elevation and in the same season of the
year. Inhabitants are easily adapted to this phenomenon, setting the settlements and
other important infrastructure on elevations above the highest recorded water level.
Usually such flooding does not pose serious threat and causes no serious flood
damage, except during extreme events, as it was in the case of the autumn 2000
floods.
Case study of the Upper Pivka valley, where floods usually cover around 6.6 km2, is
treated and explained. During the intensive rain period from September to November
2000, the groundwater table rose for about 20-35 m above the usual level, causing
flooding also in the areas, where they have never been recorded before. Precise
mapping of the flooded area extents in the discussed area and the height of the
water levels was performed. With the help of the photographic documentation,
Golden software and ArsGis 9.1 program tools the surfaces and the volumes of
the particular closed flooded areas were calculated and digitized on the map. The
continuous surface of the flood extended to 59 ha. Beside the groundwater table
rise, a surface stream, which emerged in the ancient Pivka riverbed, additionally
contributed to the flooding in the area, especially in the Bač settlement. Though the
residents are aware of flood risk and adapted to the floods with some technical
provisions (e.g. lifting roads above the usually flooded areas), the long-term spatial plan
neglects mapped flood risk areas, but it allows new buildings to be set up. In this
manner the need to comprehensive knowledge of the natural hazards problematic is
emphasised. A stress is laid also to the well considered land use planning, which is the
basis for the reduction or even prevention of negative consequences of such events. |
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