Bartłomiej Wyżga

TL;DR: In this paper, a review of a number of documented case studies from various countries and a detailed analysis of sediment exploitation from five rivers in Italy and Poland is presented, where the authors discuss alluvial river response to extensive sediment mining.

TL;DR: From an extensive student perception survey, it is shown that most of the groups from nine countries in the world considered riverscape with wood to be less aesthetic, more dangerous, and needing more improvement than riverscapes without wood.

TL;DR: In this paper, the spatial and temporal patterns of the twentieth-century channel changes of the Dunajec, the second largest river of the Polish Carpathians, are analysed using data from six historical maps, hand-auger drillings in paleochannels and hydrometric data from 10 gauging stations.

Abstract: In the twentieth century Polish Carpathian rivers were considerably modified by channelization and gravel mining, with significant detrimental effects to their ecological integrity, vertical stability of the streambeds and flood hazard to downstream river reaches. Restoration of the rivers is thus necessary to improve their ecological status and re-establish geomorphic dynamic equilibrium conditions. Various approaches to defining hydromorphological reference conditions, proposed to date in river restoration literature, have serious deficiencies. In particular, environmental changes that took place in the catchments of Carpathian rivers during the twentieth century invalidate the historical state of the rivers as reference for their restoration. This is illustrated by a change from bar-braided to island-braided channel pattern that occurred in the past century in unmanaged sections of the Czarny Dunajec in response to a reduction in flow and sediment dynamics of the river. We indicate that reference conditions should be defined as those which exist or would exist under present environmental conditions in the catchment but without human influence on the channel, riparian zone and floodplain of the river which is to be restored. This assumption was tested through the evaluation of hydromorphological river quality of the Czarny Dunajec according to the European Standard EN-14614. The evaluation confirmed a high-status hydromorphological quality in an unmanaged channel section, which can thus be used as a reference for restoration of impacted river sections. Copyright © 2012 John Wiley & Sons, Ltd.

TL;DR: In this paper, the authors examined the response of a gravel-bed stream following narrowing and straightening of its channel and found that the change from a slow and relatively steady degradation in the lower reaches to separate degradation events in the higher reaches is attributed to the differential rate of headcut retreat and to the control exerted by mid-channel bars upon the rate of river-energy dissipation.