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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Badania Fizjograficzne, Seria A, Tom 56, 2005, s. 107-135

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83-7063-456-7

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Uniwersytet im. Adama Mickiewicza w Poznaniu
Biblioteka Uniwersytetu im. Adama Mickiewicza w Poznaniu
Ministerstwo Nauki i Szkolnictwa Wyższego