Zmiany natężenia transportu materiału wleczonego w dolnym odcinku rzeki Obry w okolicach Międzyrzecza
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Date
2005
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Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk
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Abstract
Investigation concerning changes of bed-
-load transport rate was done in the lower
course of the Obra river valley near Międzyrzecz
(Western Poland). Detailed research was
conducted in chosen section of the valley, 1 km
long and 70-150 m wide. Bed load transport rate
was estimated using the model of potential sand
material transport (MŁYNARCZYK 1996). Calculated
bed-load transport rates illustrate relatively
small intensity of this sort of material transport
in particular river bed cross-sections. One of the
reasons could be occurrence of comparatively
low flow velocities in bed zone (0.05 m/s in
bank zones and 0.3 m/s in current zone). Besides,
it was observed that at high water stages
very coarse sediments (mean diameter -2.0 phi)
are exposed in current zone. This kind of material
can not be transported in hydrological
conditions which are present in the Obra river
bed. These course sediments originate from washing
away glacial till which lies beneath alluvial
sediments.
On the basis of dependence between bedload
transport rate and water stages, annual
bed-load transport rate was estimated for period
1971-1991. The dependence was achieved
using data from field measurements. The biggest
amount of bed-load transport occurred in
hydrological years with intensive floods. During
such flow events water stages reached 320 cm.
In such cases, length of high water stages period
was very important because of presence of hydrological
conditions that increased amount of
transported bed-load.
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Citation
Badania Fizjograficzne, Seria A, Tom 56, 2005, s. 107-135
Seria
Seria A - Geografia Fizyczna Tom 56;
ISBN
83-7063-456-7
ISSN
0067-2807