Karst Flash Floods
An Example From The Dinaric Karst (Croatia)
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https://doi.org/10.5194/nhess-6-195-2006 <-- shared (older) paper
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H/T Sofie de Volder | Co-founder TRAQUA โข Flooding your feed with groundwater stories
[the background in part โ with the karst geology, hydrogeology, hydrology and extreme weather - of the some of the flooding photos you might have been seeing recently from Spain, specifically ๐๐ฟ๐ฎ๐๐ฎ๐บ๐ฒ๐น๐ฎ in Andalusia, Spain]
โA karst burst is the extreme, rapid response of a karst system (a network of underground caves, conduits, fractures and aquifers) to intense or prolonged rainfall.
When the system becomes saturated, the increase in water pressure can cause groundwater levels to rise above ground level. This can lead to flash flooding, sinkhole formation and hydroseismic activity (small earthquakes caused by the movement of water).
Water is forced through natural vents or fissures, or even through artificial infrastructures such as drains, wells or toilets. Sinkholes that usually swallow rainwater can suddenly become springs.
The ๐ณ๐น๐ผ๐ผ๐ฑ๐ถ๐ป๐ด ๐ถ๐ป ๐๐ฟ๐ฎ๐๐ฎ๐บ๐ฒ๐น๐ฎ, province of Cadรญz, Spain, is a prime example of this phenomenon. Storm Leonard dumped over 500mm of rain in 24 hours on Grazalema, a small municipality built on top of a karst aquifer.
The karst became so saturated, with groundwater levels rising 200m above normal, that water began to spout from the ground, the streets and even the electrical outlets. For safety reasons, the town was completely evacuated.
Karst bursts are relatively rare, but they are likely to become more frequent because of climate change and intense localised rainfall.
๐ฅ๐ถ๐๐ธ๐ ๐ถ๐ป๐ฐ๐น๐๐ฑ๐ฒ:
โ ๏ธ ๐จ๐ป๐ฝ๐ฟ๐ฒ๐ฑ๐ถ๐ฐ๐๐ฎ๐ฏ๐น๐ฒ ๐ณ๐น๐ฎ๐๐ต ๐ณ๐น๐ผ๐ผ๐ฑ๐, even in areas that are not usually prone to flooding.
โ ๏ธ ๐ฆ๐๐ฟ๐๐ฐ๐๐๐ฟ๐ฎ๐น ๐ฑ๐ฎ๐บ๐ฎ๐ด๐ฒ to buildings and infrastructure.
โ ๏ธ ๐๐ฒ๐๐๐ฎ๐ฏ๐ถ๐น๐ถ๐๐ฎ๐๐ถ๐ผ๐ป ๐ผ๐ณ ๐๐ต๐ฒ ๐๐ป๐ฑ๐ฒ๐ฟ๐ด๐ฟ๐ผ๐๐ป๐ฑ due to new sinkhole formations, activated fractures or underground collapses.
Although the water is retreating and the karst is discharging excess groundwater, this does not mean that the inhabitants of Grazamela can safely return to their homes yet.
The discharge process was accompanied by underground knocks and small vibrations. The karst is releasing some of the pressure, and the water has flushed away some of the debris and sediment that were clogging up the conduits.
Once the groundwater level has stabilised, an in-depth risk assessment will be required to determine the risk of subsidence, sinkhole formation or landslides.
๐จ๐ป๐ฑ๐ฒ๐ฟ๐๐๐ฎ๐ป๐ฑ๐ถ๐ป๐ด ๐ฎ๐ป๐ฑ ๐บ๐ผ๐ป๐ถ๐๐ผ๐ฟ๐ถ๐ป๐ด ๐ธ๐ฎ๐ฟ๐๐ ๐๐๐๐๐ฒ๐บ๐ ๐ถ๐ ๐ฎ ๐ฐ๐ฟ๐ถ๐๐ถ๐ฐ๐ฎ๐น ๐๐๐ฒ๐ฝ ๐๐ผ ๐ฝ๐ฟ๐ฒ๐ฝ๐ฎ๐ฟ๐ฒ ๐ณ๐ผ๐ฟ ๐ฑ๐ถ๐๐ฎ๐๐๐ฒ๐ฟ๐ ๐ถ๐ป ๐ธ๐ฎ๐ฟ๐๐ ๐ฟ๐ฒ๐ด๐ถ๐ผ๐ป๐ ๐๐ผ๐ฟ๐น๐ฑ๐๐ถ๐ฑ๐ฒโฆโ
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โFlash floods constitute one of the deadliest and costliest natural disasters worldwide. This paper explains the karst flash flood phenomenon, which represents a special kind of flash flood. As the majority of flash floods karst flash floods are caused by intensive short-term precipitation in an area whose surface rarely exceeds a few square kilometres. The characteristics of all flash floods are their short duration, small areal extent, high flood peaks and rapid flows, and heavy loss of life and property. Karst flash floods have specific characteristics due to special conditions for water circulation, which exist in karst terrains. During karst flash floods a sudden rise of groundwater levels occurs, which causes the appearance of numerous, unexpected, abundant and temporary karst springs. This paper presents in detail an example of a karst flash flood in the Marina bay (Dinaric karst region of Croatia), which occurred in December 2004โฆโ
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