Tytuł pozycji:
Hydrogeomorfologiczne skutki intensywnych opadów na międzyrzeczu Bystrzycy i Giełczwi (Wyżyna Lubelska)
On
the 31st July – 6th August 2005 in Lublin
surroundings, high and intensive rainfalls
appeared (Table 1). The highest one took
place at night of 3rd–4th August and its level
exceeded 100 mm in two stations (Fig. 1).
It was the rain of changeable intensity to
1 mm·min–1, lasting 4–5 hours. In the area
of 400 square kilometers enclosed with 100
mm isohyet, an intensive runoff with erosional
effects appeared. Its size in rural area
was conditioned by land use, crop structure,
fi eld pattern and road network. Majority of
corn fi elds determined the predominance of
dispersed runoff and little rainwash. Concentration
of runoff and linear erosion took
place only on small area of: roads, fi elds
with root plants and fi elds of aerated soil
(Fig. 3). The maximum of erosion rate in
the fi eld scale reached: 200 t·ha–1 of translocated
material and 70 t·ha–1 of carried material,
fi eld surface lowering by 5 mm and
convex parts of slope by 8 cm. Deposition
of material, in form of fans and proluvial
covers took place in dry valley fl oors. Concentrated
runoff formed here episodic channels:
transport and deposition in channels
being fl at and erosional channels in crops
with uncovered soil. Below roads crossing
the channels, potholes with the capacity
to 50 m3 and bars of eroded material were
formed. Most of moved soil material was left
within dry valleys whereas water runoff was
the main source of fl ood waters in river valleys.
Specifi c outfl ow from dry valley catch ments, with the area of 5 square km, reached
1–2.5 m3·(s·km2)–1. In valleys of small perennial
fl ows with catchment area less than
50 square km (for instance: Skrzyniczanka,
upper Stawek and Sierotka Streams), located
in zone of the highest rainfall, local fl oods
appeared. They caused losses in road and
hydrotechnical infrastructure. Waves from
these catchments, with specifi c outfl ow to 0.8
m3·(s·km2)–1, caused relatively smaller fl ood
waters in higher valleys in next days (Fig.
2). Five-times growth of fl ow in Biskupice
on the Giełczew River and seven-times one
in Sobianowice on the Bystrzyca river occurred.
On 4th–11th August period, about 12
mm of water fl owed from these catchments
but in the Czerniejówka catchment, level of
groundwater raised about 30–70 cm.