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The aim of the article is to show how the fluvial processes in rivers and their valleys can support wetland restoration activities. The exemplary objects were localized in the Upper Vistula Basin (Poland) and dealt with riverbed stability, channel capacity as well as revitalization of rivers with their valleys regarding wetland restoration. All of the mentioned parameters depend on the intensity of fluvial processes in rivers, especially meandering, anastomozing or braided. Rivers always tend to reach the state of hydrodynamical balance reflecting the actual river dynamics. The nature of channel transformation is quite complex. For example, the curvature of natural river increases proportionally to the transported load alimentation and inversely to the slope of the river. The human-modified rivers also tend to increase the curvature of their channels. Interestingly, all rivers create wetlands in the areas naturally connected to the main channel. Those wetlands are regularly watered by flood events. As a result, the areas with wetlands are a perfect natural environment for fauna and flora. River channels which are situated close to such an environment are also rich in fish and invertebrates. Wetlands in mountainous areas are rare or unique unlike in lowlands where they are more likely to be found. The channel incision reduce a possibility of wetland formation in the river valley, especially after bank enforcement. The presented case studies are the effect of different projects running by the Department of Water Engineering and Geotechnics, the University of Agriculture in Kraków on the rivers and streams: Vistula, Nida, Porębianka, Czarny Dunajec. These rivers differ in many aspects; however, each of the them is located in an area where wetlands or wetted areas are likely to appear. Among the described rivers are lowland and mountain rivers. Some of them are managed according to the European Water Framework Directive, i.e., in a close-to-nature manner.

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J o a n n a P a k u l n ic k a *, W ojciech B a r t n i k ** C hanges in th e fauna o f aquatic b e e tle s (Coleoptera aquatica) in Lake L uterskie (O lsztyn Lake D istrict) in 1 9 8 1 -1 9 9 3 A b stract. Ninety-five species of a q u atic b eetles were observed in th e w eakly e u tro p h ic Lake L u t erskie. The d o m in a n ts were: Noterus crassicornis, H aliplus flauicollis a n d H. im m aculatiis. Over 13 y ears th ere w as a decrease in the com m u n ity a b u n d a n c e of a q u a tic beetles. C h an g es took place also w ith re sp e c t to th e o ccu rren ce of th e species, d o m in atio n s tru c tu r e (a d e c re a se in the a b u n d a n c e of H aliplidae, an d a n in crease in the a b u n d a n c e of D ytiscid a e com m unities) an d synecological g ro u p in g (a d ecrease in th e n u m b e r of lake-river elem ents, a n d an in crease of sm all w ater-body species). T hese ch an g e s clearly indicate p ro g ressin g e u tro p h ic a tio n of th e lake u n d e r stu d y .

Radioactive tracer measurements carried out in three Polish mountain rivers have allowed to determine the critical dimensionless shear stress, fi' required to set in motion a given size d i of particles. The different functions, fm]fi = ~(di/dm) (fm -the critical dimensionless shear stress relative to the mean grain diameter, dm) , have revealed that extrapolation of results from some rivers studies is very difficult. An attempt at determination of incipient bed load motion, on the basis of the grain size distribution has been made.The measured grain size distributions before and after flood could be compared with the radio tracer measurements results. The Gessler (1970) function has been applied to determine the armour layer motion beginning. The critical shear stress values were obtained for the all particle diameters at which their motion had begun, fm = 0.034 -0.040 corresponding to d m ~ 0.07 -0.14 m. The standard deviation of the grain size distribution was variable ~= 1.8 -3.2 .The presented investigations concern the floods, when the maximum water flow was Qmaxl = 5.50 m3/s, Qmax2 = 2.75 m3/s, Qmax3 = 5.75 m3/s, Qmax4= 5.90 m3/s+ The amounts of the transported bed material during these floods were: Gl= 6.25 T, G2= 2.70 T, G3= 57.4 T, G4= 181.1 T.It was concluded that the proposed method can be used in many similar cases if the incipient motion of bed materials is too difficult to measure, but only when the changes of the river bottom caused by flood are known.