Wetlands in River Valleys as an Effect of Fluvial Processes and Anthropopression - Wetlands and Water Framework Directive: Protection, Management and Climate Change - page 82

Additionally, while restoring the waterway, many investigations accompanying the
restoration could be done.
The Nida River basically

flows across the close to nature, cultural landscape.
The area of the widened valley, commonly referred to as

fl

“ the middle delta ” , was

once very attractive for its morphological structure and fluvial activity, not to

mention a great diversity of ecosystem. At present, the area requires serious res-
toration after introducing unnecessary river-regulating works. The system of the
cut-off channels is still recognizable and may well be recreated. Nida, however,
used to be very morphologically active, creating new branches and oxbow lakes.
After river training, the main channel had been stabilized. The old channels slowly
dry and their vulnerable surroundings loose the environmental meaning. Even if
some areas are used as grasslands, the dynamics of the river system should be
restored. This could be initiated by irrigating the old channels and recurving the
regulated river. The system then could slowly rebuild the reach and environmen-
tally precious wetland system.
Por

fl

is The migration zone is
decreased there by about 50 %, but ramp construction lets the bed material to
overcome them and to create bars in this river. Currently the best solution for
Por

ę bianka fl flows in the lower run over the RHS '

ę

bianka river is to limit the human expansion within the river migration zone
and to rebuild the river training system in the middle run in villages of Czarna
Por ę ba and Nied ź wied ź form weirs to RHS ' s. The increase of bedload rate would
positively change the flood capacity of the channel. Thus, these investigations could

improve the connection between river and its valley as well as the morphological
activity of Mszanka River, below the Por

fl

bianka outlet. The rebuilt system would
create wetted areas much more extensively then presently.
The discussed fragment of the Czarny Dunajec River is formed naturally but
endangered by a limited transport of alluvial material. The river migrates aside, and
this process slows down the channel incision. However, the process of steady
growth of channel

ę

fl flow capacity is already observed in this section; the river may

still flow in the braided channel. Thanks to the fens, it makes an excellent place for

plant and animal habitats. The future discontinuation of the river out

fl

fl ows onto the

valley could be a possible result.
Wetlands are regularly refreshed by flood events. Natural rivers continuously

transform their channels, creating oxbow lakes; as a result, the nature enrichment
develops. Moreover, they improve the retention conditions in river valleys. The
man has always attempted at occupying these areas as their soil fertility makes them
very attractive for cultivation. As long as wetlands and oxbow lakes are a result of
fl

fl

fluvial processes existing in rivers, human should take into consideration the natural
consequences, especially of river channel narrowing. The adequate processes of
river channel transformation appear during average or high fl flows, while during

designing processes of river training works mostly average fl flows are considered.

This re ects in long term on river incision.

It is much easier to remedy environmental values in regions which are not
urbanized and intensively cultivated or even not used at all. River training often
destabilizes

fl

fl fluvial processes but in urbanized basins the whole hydrological,