Morphological changes of the floodplain reach of the Taro River (Northern Italy) in the last two centuries

Short-Term GIS Analysis for the Assessment of the Recent Active-Channel Planform Adjustments in a Widening, Highly Altered River: The Scrivia River, Italy

“…Numerous studies have documented this new and recent phase of channel widening along several Italian rivers just from the 1990s onwards [21,24,25,29,30,42,43]. However, the triggering factors of this phase are still quite debated; moreover, a high uncertainty regarding its diffusion and the combination between active-channel widening and channel incision, aggradation or bed stability still exists.…”

“…However, aiming to precisely define the ongoing morphological dynamics, the most suited time span to consider for analyzing the riverbed adjustments ranges from the present-day to approximately 10-25 years ago [11,22,23].Previous studies concerning the morphological evolution of Italian rivers outlined their main morphological tendencies over the last two centuries, that is substantially before the occurrence of the most intense and widespread anthropic interventions on fluvial systems. As reported by several authors [18,[24][25][26][27][28], three evolutionary phases can be recognized: (i) the first one, from the last decades of the 19th century to the 1950s, is generally characterized by gentle narrowing and incision albeit, in some cases, no large-scale dominant processes are recognizable up to the beginning of the 20th century [18]; (ii) the second one, from the 1950s to the 1990s, presents the most relevant channel adjustments related to fast, severe and generalized narrowing and incision processes, coupled with a reduction in braiding degree and with an increase of sinuosity; (iii) the third one, from the 1990s onwards, shows a reversal trend since it is characterized by active-channel widening and by an overall slight aggradation or bed-level stability; however, this latter phase is documented only along some rivers [25,29,30].The causes behind the 20th century channel changes are now widely documented [18,21] and have been recognized in the reduction of the sediment budget due to in-channel quarrying activity [19,31], occupation of areas of fluvial pertinence [21,32], channelization [19,33,34], land-use changes at catchment scale [16,30,[35][36][37][38] and building of cross works such as weirs and dams [39][40][41]. On the contrary, the triggering factors of the most recent phase are still quite debated in the scientific literature…”

“…Previous studies concerning the morphological evolution of Italian rivers outlined their main morphological tendencies over the last two centuries, that is substantially before the occurrence of the most intense and widespread anthropic interventions on fluvial systems. As reported by several authors [18,[24][25][26][27][28], three evolutionary phases can be recognized: (i) the first one, from the last decades of the 19th century to the 1950s, is generally characterized by gentle narrowing and incision albeit, in some cases, no large-scale dominant processes are recognizable up to the beginning of the 20th century [18]; (ii) the second one, from the 1950s to the 1990s, presents the most relevant channel adjustments related to fast, severe and generalized narrowing and incision processes, coupled with a reduction in braiding degree and with an increase of sinuosity; (iii) the third one, from the 1990s onwards, shows a reversal trend since it is characterized by active-channel widening and by an overall slight aggradation or bed-level stability; however, this latter phase is documented only along some rivers [25,29,30].…”

“…The causes behind the 20th century channel changes are now widely documented [18,21] and have been recognized in the reduction of the sediment budget due to in-channel quarrying activity [19,31], occupation of areas of fluvial pertinence [21,32], channelization [19,33,34], land-use changes at catchment scale [16,30,[35][36][37][38] and building of cross works such as weirs and dams [39][40][41]. On the contrary, the triggering factors of the most recent phase are still quite debated in the scientific literature [29,30] and according to previous research could be related to: (i) the end of the in-channel sediment mining for commercial purposes, which is dated back around the late 1980s-early 1990s [20,42,43], (ii) changes in the riverbed geometry resulting in an increase of unit stream power [44], and/or (iii) the occurrence of large flood events [21,24,25,29,30].…”

Biomorphodynamics of alternate bars in a channelized, regulated river: An integrated historical and modelling analysis

“…Liébault and Piégay, 2002), planform (e.g. Abate et al, 2015;Clerici et al, 2015;David et al, 2016;Magliulo et al, 2016), channel and floodplain geomorphic features (e.g. Adami et al, 2016) and vegetation cover (e.g.…”