Morphological changes and human impact in the Entella River floodplain (Northern Italy) from the 17th century

Catena 182 (2019) 104122

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Morphological changes and human impact in the Entella River floodplain (Northern Italy) from the 17th century

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Anna Roccatia, Francesco Faccinia,b, , Fabio Luinoa, Jerome V. De Graffc, Laura Turconia a

Istituto di Ricerca per la Protezione Idrogeologica, Consiglio Nazionale delle Ricerche, Strada della Cacce 73, 10135 Turin, Italy Dipartimento di Scienze della Terra, dell'Ambiente e della Vita, Università di Genova, Corso Europa 26, 16132 Genoa, Italy c Department of Earth & Environmental Science, California State University, M/S ST24, Fresno, CA 93740, USA b

A R T I C LE I N FO

A B S T R A C T

Keywords: Channel morphological changes Fluvial dynamics Human impact Liguria

In this article the morphological changes undergone by the Entella River (Northern Italy) over the last four centuries has been investigated. The historical analysis has allowed reconstruction of fluvial evolution and shoreline dynamics and demonstrated their relationship to human disturbance over a very long period compared to most previous studies in Italy and Europe. A set of 12 historical and current maps and aerial photos, ranging from the 17th century to the present, were entered into a Geographic Information System (GIS) in order to calculate four morphological parameters (i.e., channel length, width, sinuosity and centreline shifting) and the distance of the shoreline. Modification of the Entella River over the 360-years period 1656–2016 include: i) a reduction in channel length by 128 m (3%); ii) a mean narrowing of 56 m (46%); iii) a decrease in total sinuosity from 1.10 to 1.05, with a variation in river pattern, from sinuous to straight; iv) a total shifting of the centreline of 30 m. This evolutionary trend is consistent with most of the previous studies on Italian and European rivers. Conversely, the total channel shortening and the recent phase of substantial morphological stability, with a slight increase in channel width and length, seems to be in contrast with the results of other studies. We correlated the channel planform changes and the regression of the shoreline, at least until the latter 20th century, to the reduction in sediment supply produced by the morphological modifications due to human intervention. At the beginning of the 19th century and, later, from the 1950s to the end of the 20th century, channelization, channel diversion, land-use changes and coastal defences accounted for this supply change to the Entella River and its floodplain. Furthermore, our findings reveal that human disturbance has contributed to increased flood risk in the plain, through the progressive reduction in width of the riverbed and the increasing urbanization along its riverbanks. At the same time, channelization seems to have a negative effect not only on the morphological evolution of the river, but also in terms of prevention and flood risk reduction within the floodplain.

1. Introduction Several Mediterranean and Italian rivers and their floodplains have experienced substantial morphological modifications over the past three centuries, due to a combination of natural phenomena, such as large floods, climate conditions changes, sea level fluctuations, and human disturbance, such as channel modification, land-use changes, urbanization, and mining (Perego, 1994; Billi and Rinaldi, 1997; Capelli et al., 1997; Castaldini et al., 1999; Castaldini and Ghinoi, 2008; Surian, 1999, 2003; Aucelli and Rosskopf, 2000; Marchetti, 2002; Surian and Rinaldi, 2003; Rinaldi, 2003; Surian et al., 2009b; Comiti et al., 2011; Ziliani and Surian, 2012; Segura-Beltrán and Sanchis-Ibor, 2013; Clerici

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et al., 2015; Maraga et al., 2015; Meneses et al., 2017). Before the 19th century, human modification included mainly channelization and diversion to provide flood protection and to increase the agricultural capacities of the plains. Since the 19th century, river channel and landuse were greatly modified by an increasing urban development, with substantial planform channel changes, including narrowing, channelization, displacement and covering of the riverbeds (Marchetti, 2002; Caporali et al., 2005; Clerici et al., 2015; Roccati et al., 2018), and variations in the shoreline due to fills, embankments, and the construction of coastline protection structures and tourist ports (Scorpio and Rosskopf, 2016; Brandolini et al., 2017; Donadio et al., 2017). Morphological adjustments in rivers and floodplains and their

Corresponding author. E-mail address: [email protected] (F. Faccini).

https://doi.org/10.1016/j.catena.2019.104122 Received 20 June 2018; Received in revised form 29 April 2019; Accepted 10 June 2019 Available online 17 June 2019 0341-8162/ © 2019 Elsevier B.V. All rights reserved.

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Fig. 1. Entella River basin and the surrounding areas. The red area shows the floodplain analysed. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

to the knowledge framework on morphological changes into the Mediterranean river systems.

correlation with natural and anthropic controlling factors, can be determined by the analysis of morphological parameters, such as channel length, width, depth, braiding, sinuosity, shifting and pattern, as proposed by various researchers (Rinaldi et al., 1997; Gurnell et al., 2009; Ziliani and Surian, 2012; Segura-Beltrán and Sanchis-Ibor, 2013; Clerici et al., 2015). River planform changes can be defined, in qualitative and quantitative terms, by a multi-temporal cartographical comparison, greatly improved using Geographical Information System (GIS) technology (Downward et al., 1994; Gurnell et al., 1994, 2009; Clerici et al., 2015, 2016). The floodplain of the Entella River (Fig. 1), one of the largest urbanized coastal flat areas in the Ligurian region, northern Italy, has undergone substantial morphological changes over the last four centuries due to both natural phenomena, including several large disastrous floods (Sanguineti, 1953, 1958; Casaretto, 2003), and an increasing, extensive human disturbance (Faccini et al., 2015, 2017; Roccati et al., 2018). In this paper, we provide an evaluation of the fluvial evolution of a Mediterranean coastal floodplain, with the aims of: i) reconstructing the main morphological and channel planform changes of the Entella River and the shoreline dynamics over a four-century period (1656–2016) using historical and recent maps and aerial photos improved by the use of GIS (Capelli et al., 1997; Caporali et al., 2005; Clerici et al., 2015); ii) to investigate the correlation between the morphological evolution of the riverbed and the anthropic disturbance; iii) point out the negative implications of the channel adjustments due to human activity on the flood risk of the urbanized plain and iv) provide a further contribution

2. General setting The analysed study area corresponds to the Entella River floodplain (Fig. 1) that extends for 7 km2 from Tigullio Gulf toward the eastern Ligurian hinterland and represents one of the largest flat areas of the Tyrrhenian sector of the Ligurian Apennines. Three watercourses cross through the alluvial plain: the Entella River, the major one, in the central sector, and the Rupinaro and Fravega Torrents, in the western and eastern sectors respectively. The Entella River is one of the main Ligurian watercourses flowing into the Tyrrhenian Sea. Its basin extents for 375 km2 and is formed by three tributaries, i.e. the Lavagna catchment (160 km2), the Sturla catchment (130 km2) and the Graveglia catchment (63 km2). The Entella River begins in Carasco municipality at the confluence of the Lavagna and Graveglia torrents. Shortly before the union of these two watercourses, the Lavagna Torrent receives from the northeast the flow of a third important stream, the Sturla (Fig. 1). The Entella River is a single-thread, meandering channel for about 4 km in the upper part, then straightens for 5 km in the lower part. The mouth is narrow (approximatively 100 m) and westward oriented; a sandbar frequently forms, partially blocking the regular outflow of the river. The Entella River floodplain formed by the combined and cyclical effects of fluvial and marine processes. On one hand, the progressive accretion of the plain, due to the sediment supply, and transport 2

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Fig. 2. Surficial materials map of the Entella floodplain. 1. Gravel, with subordinate sand and little or no fines; 2. sands, with significant fines; 3 sands, with subordinate gravel and little or no fines; 4. very silty sand, gravelly silt and sandy silt; 5. clayey silt and inorganic silty clay, with sand or gravel; 6. man-made deposits, including coarse soil frequently mixed with heterogeneous material (pitch, bricks, etc.); 7. marshes, swamps. Red line indicates the boundary of the Entella River catchment. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

the fluvial deposits in large sectors of the floodplain. Sandy soils characterize the coastal marine deposits, whereas clayey and inorganic soils are representative of some small fluvial and swampy deposits, typical of a low-energy fluvial environment formed by the past overflows and migration of the riverbed in the plain (Lagomaggiore, 1912). Man-made deposits, including fills and embankments (ports, railway

material discharged by the Entella River, together with that supplied by two small neighbouring torrents, Fravega and Rupinaro. On the other hand, the erosion and redistribution of the discharged alluvial material attributable to wave action and current drift effects. Alluvial soils, recent in age, can be classified based on grain-size analysis (Faccini et al., 2012) (Fig. 2). Gravelly and silty soils represent 3

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Table 1 Overview of the historical and recent maps and photos used in the research. A “palmo” (*) was an ancient unit of length measurement used in the Genoa maritime republic until the 19th century; in the metric system, it corresponds to 0.248083 m, as officially defined in the historical conversion table of the Kingdom of Italy (Ministero di Agricoltura, Industria e Commercio, 1877). Map name

Author/authority

Scale

Year

Fig./Tab. reference

Sketch map Historical map Historical map Main map Cadastral and main map Details campaign map Location plan Topographical map Black-and-white aerial photo Technical map High-resolution satellite image

Unknown – State Archive of Genoa Vinzoni M. Vinzoni M. Unknown-collection Italian Military Geographical Institute Napoleonic Cadastre—Italian Military Geographical Institute Savoy Kingdom Army—Italian Military Geographical Institute Tirelli A.A. Italian Military Geographical Institute Italian Military Geographical Institute Liguria Region Google Earth

Palmo* Palmo* Palmo* 1:9450 various 1:9450 1:10,000 1:25,000 1:65,000 1:5000 –

1656 1758 1773 1800 1807–1811 1815–1826 1915 1936 1954 1990–2007 2016

Table 2, 4, 6, 8; Figs. 4, Table 2, 4, 6, 8; Figs. 4, Table 2, 4, 6, 8; Figs. 4, Table 2, 4, 6, 8; Figs. 5, Table 2, 6; Fig. 9 Table 2, 4, 6, 7, 8; Figs. Table 2, 6, 7, 8; Figs. 5, Table 2, 6, 7, 8; Figs. 5, Table 2, 6, 7, 8; Figs. 5, Figs. 1, 2, 3, Table 2, 6, 7, 8; Figs. 5,

5, 5, 5, 6,

6, 6, 6, 7,

7, 7, 7, 8,

9, 9, 9, 9,

10, 11 11 11 11

5, 6, 6, 6,

6, 7, 7, 7,

7, 9, 8, 9,

8, 9, 11 11 9, 11 11

6, 7, 9, 10, 11

centuries (i.e. bridges construction, channelization, straightening, urbanization, etc.), were reconstructed using original contemporary documents contained in the historical archives or reported in more recent works by other authors (Rocca, 1678; Giustiniani, 1854; Lagomaggiore, 1912; Sanguineti, 1953; De Negri, 1971; Del Soldato, 1987; Casaretto, 2003). Analysis of the morphological changes in the Entella River floodplain, in terms of channel and coastline adjustments, was performed by comparing both historical and current topographical and cartographical maps and photos, ranging from 1656 to 2016. In recent years, historical cartography has increasingly become an important resource for the analysis of environmental changes, facilitated by the availability of cartographical material in digital form and the use of GIS (Downward et al., 1994; Gregory and Ell, 2007; Lukas, 2014; Statuto et al., 2017). Historical maps provide unique information at a topographical scale useful for analysing river and coastline modifications. Maps and photos used in the reconstruction and estimation of morphology variations over the last four centuries are listed in Table 1. Maps and photos were integrated in QGIS to compare present and past configuration of the Entella River and its floodplain. Raster scans of the historical paper maps and aerial photos do not contain geographical information (i.e., longitude and latitude values) and they must be georeferenced. To that end, we selected visible landmarks, called Ground Control Points (GPC), and added them on each scanned map. Next, we aligned these control points with their actual geographical location by assigning to each GPC the geographical coordinates associated with the equivalent landmarks on the modern, georeferenced technical map. As landmarks, we used targets reliably identified on the raster dataset, and in the georeferenced map, such as churches, buildings or natural benchmarks. To compute the error for each georeferenced map, we calculated the Root Mean Square Error (RMSEtot), as the square root of the mean squared error (RMSEgpc), the value that describes how consistent the transformation is between the different control points (Table 2). On georeferenced and co-registered maps and photos, we used QGIS for the data digitization of the main channel and floodplain features, i.e. riverbanks and shoreline, at different periods from 1656 to 2016. This digital dataset could be used to derive both qualitative and quantitative morphological changes. A multi-temporal cartographical comparison was carried out to identify the most significant morphological modifications to both the river channel and the shoreline. To calculate the planform channel changes in quantitative terms by QGIS, we measured morphological parameters, in the first instance, at seven points easily identifiable in every map, to which the channel characteristics and changes from date to date could be referred (Fig. 3): i) the present railway line; ii) the modern bridge called “Ponte della Libertà”, iii) the old crossing-point “La Scaffa”; iv) the medieval bridge called “Ponte della Maddalena”, v) the S. Salvatore Ditch, vi) the modern bridge at Caperana and vii) Panesi village. In addition to “Ponte della Maddalena”, we identified two other reference elements, to

and road networks), are found throughout the urban areas. Alluvial fans can be observed at the mouths of lateral valleys, even though many are now entirely obliterated by the urbanization of recent decades. Marine deposits characterize the shoreline, primarily in the form of very small pebbly beaches, in the western sector, and larger sandy beaches, in the eastern sector. Tectonics strongly controlled the morphology and drainage network of the Entella River basin, as well as the coastline. Two sets of main tectonic discontinuities feature this Apennine sector (Fanucci and Nosengo, 1977): the first and more ancient is WNW-ESE oriented, whereas the second and more recent lies in an approximate orthogonal direction NE-SW. Erosive processes contributed to the morphology of the catchment area and to create abundant continental fluvial sediments. The repeated and combined effects of erosive and neo-tectonic processes caused probably the meanders within one of which rose Carasco. According to some authors (Fanucci and Nosengo, 1977), these meanders resulted by a river capture due to the Entella River, NESW oriented, against an old channel including the present watercourses of the Lavagna and Graveglia Torrents, parallel to the coastline, which flowed further eastward into the Ligurian sea. The climate conditions of the Entella River basin are directly related to its terrain features and the orographic configuration of this Apennine sector. The presence of valleys oriented approximately WNW-ESE (Lavagna and lower Graveglia valley) and NNE-SSW (Sturla and upper Graveglia valley), facilitate the movement of air masses and atmospheric disturbances pushed onshore by southerly wind. Additionally, the Apennines are close to and parallel the coastline resulting in their functioning as a barrier causing very low-pressure systems which result in heavy rainfalls, up to very strong thunderstorms (Acquaotta et al., 2018a, 2018b). This barrier effect of the Apennines in this sector is enhanced by the orographic effect from their relief being higher than 1700 m a.s.l. The mean annual rainfall of the Entella River basin is about 1800 mm, with significant areal variability due to the local orographic configuration and morphology of the relief. It ranges from 1130 mm/ year close to the mouth and more the 2200–2300 mm/year at higher altitude, in the upper Lavagna and Sturla valley respectively (Ministero dei Lavori Pubblici, 1934-2003; ARPAL-CMIRL, 2003-2010). The rainfall regime is characterized by a primary peak of precipitation in autumn (October–November) and a secondary maximum in winter (February). Consequently, the Entella river bed is never totally dry. Minimum hydrometric levels are observed in the summer months or during prolonged dry spells, whereas highest flows can be recorded during prolonged or very heavy rainfalls that affect the Entella basin in the autumn and winter months. 3. Methods Anthropic interventions carried out along the river over the last four 4

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(Hickin and Nanson, 1984). At the points of intersection between the regular reference grid and the computed axis, a number of lines orthogonal to the computed centreline were traced. The length of the transect portion between the two channel centrelines defines the channel shifting between the two dates.

Table 2 Errors in georeferencing the historical maps: the first three columns contain errors in georeferencing the raster scans in pixel, calculated using the Root Mean Square Error (RMSE). The last column shows the total errors in meters, including errors in projection map in QGIS (RMSEtot), errors linked to the scale of the maps representation and errors resulting from the manual digitization of the channel and detection of the GPC in each map. Years

RMSEtot in X

RMSEtot in Y

RMSEtot

Total errors

1656 1758 1773 1800 1809 1811 1826 1915 1954

2.2861 × 10−8 3.7046 × 10−8 1.9541 × 10−7 1.6854 × 10−8 8.9178 × 10−7 2.3704 × 10−9 3.5653 × 10−4 4.9937 × 10−7 2.9019 × 10−7

1.3250 × 10−8 1.5006 × 10−8 3.0281 × 10−7 1.5995 × 10−8 4.3145 × 10−7 1.1292 × 10−9 5.8040 × 10−4 1.3026 × 10−6 9.7922 × 10−8

2.6424 × 10−8 3.9969 × 10−8 4.0085 × 10−7 2.4000 × 10−8 9.9051 × 10−7 2.6289 × 10−9 6.8115 × 10−4 1.3945 × 10−6 3.0626 × 10−7

26.4 29.5 30.9 32.2 26.8 27.4 39.3 37.6 83.0

To reconstruct shorelines dynamics over the entire period, we also digitized the coastal line. It is generally known that errors affect the evaluation of the river channel modifications using a multi-temporal comparison of maps or aerial photos (Downward et al., 1994). It is recognized that some differences could be the result of different techniques of map representation and their scale and possible georeferencing errors of features due to less accurate detection techniques compared to the those currently in use. Specifically, measured morphological parameters can be affected by the following sources of error: i) the imprecisions associated with the registration of the different historical map sources to a common geographical base and map projection in QGIS, using a network of control points defined across the map and the aerial photos; ii) the errors linked to the scale adopted for the map representation and the iii); and the errors resulting from the manual detection of the GPC and digitization of channel boundaries in the different map sources. Total errors, in meters, are listed in Table 2. Using original contemporary documents from historical archives or reported in more recent papers by other authors (Rocca, 1678; Sanguineti, 1953; Casaretto, 2003), integrated with data about the latest events from different sources, including newspaper articles, scientific papers, technical and event reports, a catalogue of the flood events that occurred in the Entella River plain in the period 1656–2016 was compiled.

measure the coastline distance variations from date to date using the minimum distance technique: viii) the “San Giovanni Battista” Church, in Chiavari and ix) the “Nostra Signora del Carmine” Church in Lavagna, buildings dating to before the 17th century (Fig. 3). To utilize more general reference points in space and time to compute the morphological changes, a grid of regularly spaced parallel lines at 50 m intervals was digitized along the channel on the more recent map (Fig. 3). Calculation of the planform characteristics by QGIS required manual digitization of the banks as represented by the top of the scarp delimiting the channel at bankfull stage for each different period. The following morphological channel indexes and parameters were computed: i. channel length is the extent of the channel centreline (axis), which is the line equidistant from the two banks. We extracted the centreline of each date from the vector map containing the river banks: starting from the bankfull channel banks, perpendicular lines at 50 m intervals were plotted and their centroid points calculated. The line joining the computed points defines the channel centreline (Shields Jr et al., 2000; Micheli and Larsen, 2011). ii. channel width is the extent of the line, from bank to bank, orthogonal to the channel centreline. At the points of intersection between the regular reference grid and the axis, we traced a number of transects across the channel and orthogonal to the computed centreline: the length of the transect portion between the channel banks defines the channel width (Best, 1988; Finnegan et al., 2005); iii. sinuosity index is generally defined as the ratio of channel length to valley length (Schumm, 1963). We calculated first a total sinuosity, by dividing the computed total length of the channel axis by the extent of the straight-line between its endpoints. However, in order to reduce the degree of subjectivity due to the prior subdivision into rectilinear segments required for parameter evaluation, and the valley pattern of the Entella River, in this study we also calculated sinuosity index using only the channel centreline, as suggested by Clerici et al. (2015, 2016), properly adjusted to the morphological features of the study area: we considered a portion of the channel centreline with a fixed length (1 km), progressively shifted downstream by a constant distance (200 m). Sinuosity index was calculated by dividing the fixed length of the channel axis by the length of the straight-line between its endpoints. We classified sinuosity based on three types of sinuosity according to Surian et al. (2009a): straight (below 1.1), sinuous (between 1.1 and 1.5) and meandering (over 1.5); iv. channel shifting is the difference in position of the channel centreline between two dates. Using a procedure similar to the one described to define the centreline between the two channel banks, we computed the line equidistant from the two channel centrelines referring to dates, which represents axis of the two centrelines

4. Results Historical analysis over the 360-year period 1656–2016 (Fig. 4 and Fig. 9) revealed remarkable channel planform changes and shoreline modifications, compared to the present setting. Eight pairs of dates have been considered and three graphics containing curves for each time window has been constructed, corresponding to mean channel width, mean sinuosity index and mean centreline shifting (from Fig. 5 to Fig. 7); the values of the computed parameters are reported in Table 4 and Table 7. Shoreline variations are shown in Fig. 8, Table 5 and Table 6. Curves and mean values of the morphological parameters for the whole 360-years period from 1656 to 2016 are reported in Table 8. For simplicity, we assemble the eight-time windows considered in three sections: 1656–1800, 1800–1915 and after 1915. 4.1. Period 1656–1800 Visual inspection of the historical maps (Fig. 4, Table 1) reveals a progressive narrowing and eastward migration of the channel compared to the current location, particularly in the its final stretch. The active channel during the 17th century was remarkably larger (Fig. 4A) compared to the present setting, and the left bank shifted and closer to the foot of the hillslope at La Moggia, whereas the mouth was placed in front of the Capoborgo district (see location in Fig. 2). The absence of banks along the channel favoured wide marshlands originated by the larger floods throughout the 18th century (Lagomaggiore, 1912) (see location in Fig. 2), that completely disappeared later, as a result of the early drainage and hydraulic interventions along the river and next to its mouth (Pessagno, 1938; De Negri, 1971). As reported in Table 4, during the time interval 1656–1758 (102 years, the longest time period considered) the channel length increased by 145 m; in contrast, the mean width decreased by 6 m, with the higher reduction values in the upper stretch of the riverbed and at the mouth (Fig. 5). Mean sinuosity was unvaried (1.02). However, sinuosity index values increased in the lower stretch of the river (Fig. 6); 5

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Fig. 3. Buildings (red stars) and grid of parallel lines at 50 m intervals (green lines) used to fixed reference points in space and time, which the channel characteristics and changes from date to date could be referred to. Reference elements: 1, present railway line; 2, the modern bridge called “Ponte della Libertà”; 3. the old crossingpoint “La Scaffa”; 4. the medieval bridge called “Ponte della Maddalena”; 5, the S. Salvatore ditch; 6, the modern bridge at Caperana; 7, Panesi; 8, “S. Giovanni Battista” Church and 9, “Nostra Signora del Carmine” Church. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

further diverted westward from the previous configuration and the mouth was now placed in front of the old Borgolungo district (see location in Fig. 2). The main effect of the progressive deviation was a remarkable change in the channel pattern, from straight to sinuous river (Fig. 4C): the increase in sinuosity is essentially due to an

total sinuosity slightly increased from 1.10 to 1.12 and the river pattern started to change from straight to sinuous (Surian et al., 2009a). The mean shifting of the channel centreline was 9 m, with the maximum displacement of 47 m in the medium and lower stretches (Fig. 7). During the second half of the 18th century (Fig. 4B), the channel 6

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Fig. 4. Historical maps of the Entella River floodplain in the 17th and 18th centuries: (A) “Pianta topografica di Chiavari per il Magistrato della Sanità”, 1656; (B) “Pianta delle Due Riviere della Serenissima Repubblica di Genova divise ne’ i Commissariati di Sanità”, 1758; (C) “Il Dominio della Serenissima Repubblica di Genova in terraferma”, 1773. Red stars: reference elements (see Fig. 3). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) 7

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Fig. 5. Curves of channel width (in m) over the 360-years period from 1656 to 2016. Bottom x-axes show the position of the reference points (i.e., points of intersection between the grid of parallel lines at 50 m intervals and the channel centrelines) and their distances, in meters, from the first reference point at Panesi village.

accentuation of the channel bending in the final riverbed stretch, which also explains the increase in channel length. In the time interval 1758–1773 (the shortest one, 15 years), the channel length further increased up to the maximum length value of 4473 m (Table 4). The mean channel width increased by 37 m, with the higher increment at the mouth (Fig. 5). No changes in mean sinuosity (1.02) have been measured; however, the index values further increased in the lower stretch (Fig. 6). Total sinuosity further increased, and the river may be described as sinuous (Surian et al., 2009a), at least in the lower reach. The shifting of the centreline is on average 28 m and has a maximum displacement of 475 m in the final stretch of the riverbed (Fig. 7). In the same period, a progressive progradation of the shoreline has been observed (Fig. 8): results of cartographical comparison are supported by the distance values (Table 5) between the sea and the “Ponte della Maddalena” bridge and the medieval walls in Chiavari reported in the historical document and published literature (Giustiniani, 1854; Ragazzi and Corallo, 1981; Del Soldato, 1987), and by the distance values measured by QGIS between the shoreline and the reference points reported in Table 6. At the end of the 18th century, a number of rudimentary flood protection works along the river were carried out (Lagomaggiore, 1912; Pessagno, 1938; De Negri, 1971) to protect the plain against the recurrent and flood events (Table 3): i) reclamation of the marshland next to the mouth, ii) channel diversion toward the east and straightening in the final stretch, including the artificial meander cut-off, and iii) a

rudimentary channelization, with fences and levees along the right riverside. The main effect of human activity was a change in the channel pattern from sinuous to straight and the channel displacement toward east of the mouth, as shown in the historical maps dating back to the Napoleonic Age (Fig. 9A) and the first half of the 19th century (Fig. 9B). During the time interval 1773–1800, the channel length considerably decreased by 270 m and the channel width reduced on average by 50% (Table 4), with the higher reduction values at the mouth (Fig. 5). The sinuosity index also decreased from a mean value of 1.02 to 1.01, with a notable reduction in the lower stretch of the riverbed (Fig. 6). Total sinuosity strongly decreased, with a straight pattern. The mean shifting of the channel centreline is 47 m with a maximum displacement of 91 m at the mouth (Fig. 5).

4.2. Period 1800–1915 In the next time interval 1800–1826, the channel length increased by 106 m (Table 4). The mean width was unaltered; however, it is evident from the width curves in Fig. 5 that planimetric changes were not homogeneous along the channel with narrowing in the middle stretch (upstream of the “Ponte della Maddalena” bridge, R55) and at the mouth, and widening in the upper stretch of the river channel (Panesi, R0; San Salvatore Ditch, R30) and downstream of the “Ponte della Maddalena” bridge. The mean sinuosity unchanged from the 8

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Fig. 6. Curves of channel sinuosity over the 360-years period from 1656 to 2016. Bottom x-axes show the position of the reference points (i.e., points of intersection between the grid of parallel lines at 50 m intervals and the channel centrelines) and their distances, in meters, from the first reference point at Panesi village.

segment (San Salvatore ditch, R30) and at the mouth. The construction of the bridge of the Genova-Sestri Levante railway at the mouth, between 1868 and 1870, and of a new bridge on the Via Aurelia, “Ponte della Liberta” bridge, about 250 m upstream of the railway, around 1910 (Fig. 9C), produced a further riverbed channelization due to the construction of new small protection structures both up- and downstream the two bridges, with a marked narrowing particularly at and upstream the “Ponte della Libertà” bridge, as shown by curves in Fig. 5 between R45 and R70. The mean sinuosity index was unvaried (1.01), whereas the total sinuosity slightly increased from 1.04 to 1.08. Along the channel, changes in the sinuosity index were not homogeneous, with an increase in the upper and lower stretches and a decrease in the middle one (Fig. 6). The shifting of the channel centreline on average was 21 m, with a maximum displacement of 207 m at the mouth (Fig. 7). The small increase in channel width and sinuosity at the mouth was related to the hydraulic works carried out at the end of 19th century to divert westward the final stretch of the riverbed. Consequent to remarkable decrease in sediment supply due to the channelization and diversion along the lower stretch of the Entella River, the construction of new bridges, banks and coastal defences at the mouth, starting from the latter 19th century an erosive phase took place, causing a reduction of the beaches along the western sector and a progressive regression of the coastline (Rovereto, 1902, 1939; Issel, 1911; Omodei, 1912; Guarnieri, 1935; Baccino et al., 1937; Conti, 1951; Corradi et al., 2003; Roccati et al., 2018).

previous period (1.01), whereas the total sinuosity further decreased from 1.05 to 1.04. The shifting of the channel centreline on average was 46 m, with a maximum displacement of 91 m upstream of the “Ponte della Maddalena” bridge (Fig. 7). The interventions along the river carried out at the end of the 18th century, further favoured the sedimentation of alluvial deposits and shoreline progradation, due to the continue supply of materials to the plain and the beaches (Corradi et al., 2003; Roccati et al., 2018). This trend is supported by the increase in length of the distances measured between the shoreline and the reference points, up to a maximum value in 1826 (Table 6, Fig. 8). However, the distribution of the alluvial materials along the coastline was asymmetric, as a result of both natural phenomena, e.g. the drift effects induced by the wave action and longshore littoral drifts, and human disturbances, e.g. hydraulic works at the river mouth and along the coast (Rovereto, 1939; Corradi et al., 2003). The resulting asymmetric planimetric morphology of the floodplain and the coastline junction was convex in shape, on the western side, and prominently hollow in shape on the eastern side (Fig. 8). Despite the next evolutionary trends, the asymmetric morphology of the shoreline persisted until the present. In the next time interval 1826–1915, the channel increased in length by 81 m (from 4309 m to 4390 m), as reported in Table 7. Mean width slightly increased; however, it is evident from the width curves in Fig. 5 that the planimetric changes were not homogeneous along the channel, with narrowing in the lower stretch (downstream of the “Ponte della Maddalena” bridge, R55) and widening in the middle 9

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Fig. 7. Curves of channel shifting (in m) over the 360-years period from 1656 to 2016. Bottom x-axes show the position of the reference points (i.e., points of intersection between the grid of parallel lines at 50 m intervals and the channel centrelines) and their distances, in meters, from the first reference point at Panesi village.

and middle stretches of the channel (Fig. 5), with an increase of 20 m at the “Ponte della Maddalena” bridge (between R53 and R54) and 10 m at the confluence with the S. Salvatore ditch (between R30 and R31). Mean (1.01) and total (1.05) sinuosity were almost unvaried, whereas the mean shifting of the centreline was 7.6 m, with a maximum displacement value of 27 m at Caperana (R21) (Fig. 7). During the last time interval 1954–2016, the channel length slightly increased by 47 m (from 4136 m to 4182 m), in contrast with the previous generalized shortening trend (Table 7), due to the construction in the 1970s and in the 1980s of the tourist ports of Chiavari and Lavagna respectively, with new artificial areas, fills and embankments. Between the 1960s and the 1970s two new bridges were built, immediately upstream the railway bridge (“Ponte della Pace” bridge, between R74 and R75) and at Caperana (R30), with a further canalization of the riverbed and the stabilization of the river banks. Therefore, no significant changes in mean width occurred, with the lowest variation value (0.8 m) in all the time windows: the two curves in Fig. 5 overlap almost perfectly. Mean (1.01) and total (1.05) sinuosity were unvaried, and the mean displacement of the centreline was 1.3 m, the lowest value in the examined intervals. Over the 20th century, the regressive trend of the coastline went on (Fig. 8), increased by the sand and gravel quarrying from the beaches and the riverbed to satisfy the increasing demand for building materials due to the urban sprawl (Roccati et al., 2018): the shoreline retreated, up to a minimum value in 1954, as indicated by the values of the

4.3. From 1915 to the present day During the time interval 1915–1936, the channel length decreased of 283 m, which is the highest value in all the time windows (Table 7). The width decreased on average by 20 m; the narrowing affected nearly the entire channel, but with the highest reduction within the uppermiddle stretches of the riverbed and at the mouth (Fig. 5). In particular, the width channel decreased by 30 m at the “Ponte della Maddalena” bridge (between R53 and R54) and 15 m at the confluence with the S. Salvatore ditch (between R30 and R31). The marked narrowing experienced by the middle river stretches, upstream of the “Ponte della Libertà” bridge, in the first half of the 20th century was partially correlated to the early urban development of the floodplain along the western riverside (Roccati et al., 2018), between the mouth and Caperana district. No significant changes in mean sinuosity occurred (1.01), as shown by the two curves in Fig. 6, whereas the total sinuosity decreased from 1.08 to 1.05. The mean centreline shifting was 11 m, with a maximum displacement in the upper part of 38 m (Fig. 7). Because of the progressive worsening of the earlier and rudimentary fences at the mouth, a channel straightening downstream of the railway bridge was carried out and new concrete levees and small bank protection structures were built. In the time interval 1936–1954 the channel length further decreased by 16 m and reached the minimum length value of 4136 m. Mean width slightly increased by 5 m: in particular, widening has affected the lower

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Table 3 Entella River: main flood events occurred in the floodplain from 1656 to the present day. In bold are marked the most dangerous and destructive flood events; in brackets, the number of the casualties occurred. Years XVII century XVIII century XIX century XX century

XXI century

1626 (40), 1647 1701, 1702, 1737 (undefined) 1772, 1794, 1795 1886, 1892 1908, 1910, 1915 1926, 1927, 1930, 1934, 1935, 1948, 1953 (1), 1979, 1982 2000, 2002, 2009 2013 (2), 2014, 2016

Fig. 9. Shoreline dynamics over the 360-years period 1656–2016.

the beaches. However, the construction of coastal defence structures in the last decades, such as groynes, seawalls, submerged breakwaters and the artificial beach nourishment from land sources, has partially reduced the erosion of shores and coastline (Fig. 8), as shown the unvaried or slightly increased values of the distance between the shoreline and the reference points in Table 6. 4.4. Summary of channel changes Table 8 shows the morphological and planform modification of the river over the 360-years period 1656–2016: the length of the channel has decreased, with a total decrease of 129 m, and the reduction in mean width was 56 m overall. In particular, the decrease rate was the highest (51%) from 1773 to 1800, with a decrease of 76 m; a considerable decrease rate (25%) has been observed in the first half of the 20th century, from l915 to1936 (25%), with a decrease of 20 m. Whereas, the mean channel width has increased over the time period 1758–1773, with a growth rate of 33%. Fig. 10 shows the marked narrowing that affected overall the Entella River from 1656 to 2016. Mean sinuosity shows no significant changes (Table 8), with a value typical of a straight river pattern (Surian et al., 2009a): however, Fig. 10 displays a remarkable reduction in the mean sinuosity in the final stretch, according to the shortening and displacement of the channel. The mean shifting of the centreline was 30 m: as shown in Fig. 10 and according to the cartographical analysis, displacement have affected particularly the middle and lower stretches of the channel, with a maximum shifting value of 206 m at the mouth. Coastline changes are shown in Table 8: the general progradation of the shoreline has been going on over the 17th and 18th century, with a maximum increase in the central sector of 110 m, from 1773 to 1800,

Fig. 8. Historical maps of the Entella River floodplain in 19th and 20th centuries: (A) “Parte della Riviera di Levante da Chiavari a oltre Moneglia, 1800; (B) “Stati Sardi di Terraferma, Riviera di Levante”, 1816–1826; (C) “Carta Topografica d'Italia – serie 25, Foglio 94, Tavolette I-NO “Chiavari” e I-NE “Sestri Levante”, 1936. Red stars: reference elements (see Fig. 3). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

distances measured between the coastline and the reference points reported in Table 6. The generalized regressive trend resulted temporary interrupted in the period 1955–1970 due to the material supply resulting from works for roads, motorway E80 and railway networks (Corradi et al., 2003). In the 1970s, the construction of the tourist ports of Chiavari and Lavagna and the associated marina at the mouth of the Entella River has heavily modified the coastline, producing a significant advance of the shoreline and the further increasing of the erosional processes, due to the transport of the fluvial sediments to the deeper seabed and a consequent remarkable reduction in sediment supply to 11

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Table 4 Computed parameters for the dates considered from 1656 and 1826. Channel length, width, sinuosity and shifting refer to the channel reach between the first reference point at Panesi village and the last one at the river mouth (Fig. 3). Dates

1656

Years interval Channel length (m) Length variation (m) Channel width (m) Min Max Mean Mean variation Sinuosity (index) Min Max Mean Total Mean shifting centerline (m) Min Max Mean

1758

1773

102 4311.60

15

27

4457.05 145.45

72.8 347.3 120.1

4473.38

84.4 657.5 150.9

−6.4 1.00 1.06 1.02 1.12

0.5 474.9 27.8

Ponte della Maddalena

Medieval walls

Distance (m)

1210 1250 1810 1939 1530 1656 1790 1810 1830 1846

150 500 1320 1225 297 350 409 445 393 385

S. Giovanni Battista Church

Ponte della Maddalena

N.S. del Carmine Church

1656 1758 1773 1800 1809 1826 1915 1936 1954 2016

434.9 434.9 421.1 460.8 538.9 551.9 498.8 492.9 498.8 526.2

1125.2 1114.3 996.4 1105.9 1164.1 1174.5 1145.9 1074.0 1099.3 1131.1

449.7 427.7 471.4 398.3 477.5 459.1 466.6 400.1 415.5 474.2

34.3 104.6 73.8 −46,2

0.7 1.00 1.02 1.01 1.04 13.3 91.2 46.8

Historical analysis highlights remarkable morphological changes undergone by the floodplain of the Entella River over the 360-years period 1656–2016. The main transformations include channel narrowing, channelization, straightening, displacement and the progressive retreat and recent advance of the shoreline. In the comparison of historical maps, we identify a generalized decrease in channel length, width, sinuosity and shifting from 1656 to 2016 (Fig. 11), but the parameter variations are not homogeneous in the considered time windows. For example, length decreases over the entire period, except for an increase until 1773, which is closely related to the westward migration of the channel with an increase in sinuosity in the final stretch of the channel; lengthening observed in the early and latter 20th century are related to the works carried out along the riverbank, such as channelization and straightening, and the construction of the tourist ports at the mouth. Width shows a rapid increase at the end of the 18th century, a rapid decrease in the early 19th century period, due to the construction of fences and rudimentary levees, and a gradual reduction over the 20th century until the present day, correlated to the construction of concrete levees and banks, required for the building of new bridges and the urban development along the riverbanks. As a consequence of post-war reconstruction and population increase, massive gravel and sand quarrying from the Entella riverbed and the beaches was carried out to satisfy the increased demand for building materials. Due to the early urbanization of the floodplain in the early 19th century, particularly along the right riverside between the mouth and Caperana district, and the generalized rapid urban sprawl since the 1950s, other aggregate sources were no longer available (Roccati et al., 2018). Moreover, land-use changes due to the increase of the built-up areas in the floodplain, including the gradual loss of agricultural land and reforestation in the rural inland sectors of the catchment (Roccati et al., 2018), contribute to produce a remarkable reduction in sediment supply to the river channel and the beaches, and the consequent narrowing of the riverbed and progressive shoreline retreat. Mean and total sinuosity values slightly decrease from 1656 to 2016 (Table 8): however, Fig. 11 displays that sinuosity, closely linked to changes in channel length, increases until 1773, then shows a rapid decrease at the beginning of 19th century consequent to human interventions along the channel. Despite the progressive urbanization, sinuosity shows no changes over the last century (Table 8, Fig. 11): we have correlated this fact to the channelization carried out over the 20th century, particularly in the lower stretch, which has virtually fixed the channel position. Shifting shows a marked increase till 1800 due to the

Table 6 Shoreline variations over a four-century period: minimum distance (m) measured between shoreline and reference elements from 1656 to 2016 (see reference points 4, 8 and 9 in Fig. 3). Date

−2.07

5. Discussion

Table 5 Distance values between the shoreline and “Ponte della Maddalena” and the medieval walls in Chiavari reported in historical papers (Giustiniani, 1854; Ragazzi and Corallo, 1981; Del Soldato, 1987). Years

170

106.68

1.00 1.03 1.01 1.05 0.2 91.2 47.5

1656–1826

4309.53

45.3 134.0 74.5

1.00 1.07 1.02 1.14

0.1 47.5 9.3

26

−76.4

37,2

1826

4202.85 −270.53

16.33 57.1 223.1 113.7

1.00 1.04 1.02 1.10

1800

and the highest growth rate (20%) in the western sector, from 1800 to 1826. Starting from the latter 19th century, the shoreline has retreated, with a maximum decrease of 72 m in the central sector and the highest decrease rate of 14% in the eastern sector, from 1915 to 1936. However, results of the historical analysis show a generalized increase on the whole, ranging from few meters, in the central sector, next to the mouth, up to one hundred meters, in the western sector, due to fills and embankments that have deeply modified the original contour of the coastline.

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Table 7 Computed parameters for the dates considered from 1826 and 2016. Channel length, width, sinuosity and shifting refer to the channel reach between the first reference point at Panesi village and the last one at the river mouth (Fig. 3). Dates Years interval Channel length (m) Length variation (m) Channel width (m) Min Max Mean Mean variation Sinuosity (index) Min Max Mean Total Mean shifting centerline (m) Min Max Mean

1826

1915 89

4309.53

1936 21

18

4390.96

4152.49

1.00 1.03 1.01 1.05

0.3 207.1 20.6

40.8 141.6 63.6 −10,19

0.8 1.00 1.03 1.01 1.05

0.2 38.5 11.4

−126.74

46.76

5.2

1.01 1.03 1.01 1.08

190 4182.79

30.2 122.1 62.8

−19,7

3,5 1.00 1.02 1.01 1.04

29.7 91.2 57.7

1826–2016

62

−16.46

46.8 120.8 77.03

2016

4136.03

−283.47

81.43 34.3 104.6 73.8

1954

0.0 27.9 7.6

1.00 1.03 1.01 1.05 0.0 7.8 1.3

(up to 10 m) and changes in channel patterns, due to human disturbance particularly from the 1950s to the end of the 1990s. Similar trends were identified for several rivers in western (Petit et al., 1996; Liébault and Piégay, 2001, 2002; Surian and Rinaldi, 2003; Uribelarrea et al., 2003; Ollero, 2010; Segura-Beltrán and Sanchis-Ibor, 2013; Sanchis-Ibor et al., 2017), central (Kiss et al., 2008; Zawiejska and Wyzga, 2010; Kiss and Blanka, 2012) and northern Europe (Sear and Archer, 1998; Winterbottom, 2000; Surian and Rinaldi, 2003). Major morphological changes have been observed in the Entella River and its floodplain in the late 19th century and over the 20th century, particularly between the 1950s and 1980s, due to the rapid and massive urban sprawl in both Chiavari and Lavagna as a consequence of post-war population increase and economic growth (Roccati et al., 2018). The timing of the Entella River changes coincides with the time period of accelerated and strong channel variations observed in other Italian and European rivers due to human disturbance, i.e. channelization, gravel mining, construction of dams and weirs, hydraulic and regulation works, reforestation. In contrast with the results of other studies, the most recent evolutionary trend of the Entella River shows a substantial morphological stability with a slight increase in length and width, at least along some channel reaches, over the last decades of the 20th century and the early 21th century: we have correlated this trend to the construction of new banks along the riversides, and to coastal protection structures, fills and embankments next to the river mouth along the coast. The evolutionary trend of the shoreline detected in the floodplain of the Entella River over the last two centuries is comparable to similar trends observed in other coastal sector of the Mediterranean area (Lewin et al., 1995), with a continue progradation of the shoreline until the end of the 19th century, exceptionally pronounced near river mouths, and a progressive regression observed since the latter 19th

river's westward migration, and then a gradual decrease in values, with higher displacements between 1800 and 1826 resulting from the diversion and straightening works carried out in the final stretch of the channel at the end of the 18th century. We have correlated the most remarkable morphological changes of the floodplain to the human disturbance from the early 18th century until the end of the 20th century. The morphological changes assessed in the Entella river are consistent with the channel evolution observed by other authors in many Italian, Mediterranean and European rivers, at least, over the last two centuries. Even though different time windows and parameters can be adopted and considered in the quantitative analysis, narrowing of the active riverbed and changes in sinuosity and river pattern are the most observed planform transformations, as shown in Table 9. Among Italian rivers, Clerici et al. (2015) assessed a mean width decrease by 73% along the Taro River (northern Italy) until the end of the 20th century, with a reduction in braiding but an increase in channel length, sinuosity and shifting. In the Po River tributaries in northern Italy studied by Pellegrini et al. (2008), morphological changes started in the latter 19th century with an acceleration from the 1950s to 1990s, and produced a narrowing up to 80%, channel incision up to 4 m, an increase in channel length and, locally, a variation from multi-thread to single tread patterns. Rinaldi (2003) and Rinaldi et al. (2005) reported a channel narrowing > 50% in 38% of the measured reaches in the Arno River and other alluvial rivers of the Tuscany region (central Italy), incision up to 9 m and a transformation from multi-thread to singlethread sinuous channel, mainly due to human intervention between 1945 and 1980. Many rivers in southern Italy (Biggiero et al., 1994; Capelli et al., 1997; Aucelli and Rosskopf, 2000; Magliulo et al., 2013; Scorpio et al., 2015; Scorpio and Rosskopf, 2016) experienced remarkable width reduction, in some cases > 80%, intense bed incision

Table 8 Statistics on planform channel changes and variations of distance measured between shoreline and the reference points “Ponte della Maddalena” (Ref Point 4), “S. Giovanni Battista” church (Ref. Point 8) and “Nostra Signora del Carmine” (Ref Point 9) from 1656 and 2016. For reference elements location, see Fig. 3.

Length (m) Mean width (m) Mean sinuosity (index) Total sinuosity (index) Mean centerline shifting (m) Distance Ref Point 4 (m) Distance Ref Point 8 (m) Distance Ref Point 9 (m)

1626 1758

1758 1773

1773 1800

1800–1826

1826 1915

1915–1936

1936–1954

1954 2016

1656 2016

145.5 −6.4 0.00 0.02 9.3 −10.9 0.0 22.0

16.3 37.2 0.00 0.02 27.8 −117.9 −13.8 43.7

−270.5 −76.4 −0.01 −0.09 47.5 109.5 39.7 −73.1

106.7 0.7 0.00 −0.01 46.8 68.6 91.1 60.8

81.43 3.5 0.00 0.04 20.6 −28.6 −53.1 7.5

−283.5 −19.7 0.00 −0.03 11.4 −71.9 −5.9 −66.5

−16.5 5.2 0.00 0.00 7.6 25.3 5.9 15.4

46.8 0.8 0.00 0.00 1.3 31.8 27.4 58.7

−128.8 −56.4 −0.01 −0.05 30.2 5.9 91.3 24.5

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Table 9 Recent morphological channel changes due to human activity in Italian and European rivers. River

Type of morphological changes

Rivers of the Piedmont Region

Channel narrowing, width decrease to 80%; changes in channel pattern; incision Channel narrowing, width decrease to 80%; reduction in braiding; changes in channel pattern; incision Channel narrowing, width decrease > 50%; incision Channel narrowing, width decrease to 50%; reduction in braiding; incision Channel narrowing, width decrease to 70%; increase in sinuosity; changes in channel pattern; incision Channel narrowing; incision

Piave, Tagliamento and river in the Northeastern Italy

Arno

Rivers of the Tuscany Region

Taro

Tevere

Time of main morphological changes

Causes

References

up

1950s to 1980s

Gravel mining; channelization

Duotto and Maraga,1994; Surian and Rinaldi, 2003; Pellegrini et al., 2008

up

1930s to 1990s

Gravel mining; channelization; diversion; dams

Early 20th century; 1945–1960 to 1990s

Gravel mining; channelization; reforestation.

Surian, 1999; Surian and Rinaldi, 2003; Surian et al., 2009b; Comiti et al., 2011; Ziliani and Surian, 2012 Rinaldi et al., 1997; Rinaldi, 2003 Surian and Rinaldi, 2003

up

Early 20th century; 1950s to 1990s

Gravel mining; Channelization

Rinaldi et al., 2005 Surian and Rinaldi, 2003

up

Early 20th century; 1950s to 1980s

Gravel mining; channelization

Clerici et al., 2015

From early19th century to present; 1960s to 1990s 1930s–1950s to 1980s

Gravel mining; embankments; dams

Canuti et al., 1992 Surian and Rinaldi, 2003

Gravel mining; channelization; reforestation; dams

Biggiero et al., 1994; Capelli et al., 1997; Aucelli and Rosskopf, 2000; Surian and Rinaldi, 2003; Magliulo et al., 2013; Scorpio et al., 2015; Scorpio and Rosskopf, 2016 Petit et al., 1996 Surian and Rinaldi, 2003

Rivers in Southern Italy

Channel narrowing, width decrease up to 80%; incision; changes in channel pattern

Rhone (France)

Channel narrowing; incision

Rivers in Southeastern France

Channel narrowing; incision

Ebro (Spain)

Channel narrowing; changes in channel pattern; increase in sinuosity Channel narrowing; incision Channel narrowing, decrease width up to 70%; incision Channel narrowing, changes in channel pattern; incision Channel narrowing, width decrease up to 50%; changes in channel pattern; incision Channel narrowing; changes in channel pattern; incision

Rivers of Central Spain Rivers of Eastern Spain Rivers in Southern Poland Rivers in Hungary

Rivers in United Kingdom

Latter 19th century; early 20th century; 1970s to 1980s Early 20th century; 1950s to 1970s 1980s to 1990s

Channelization; gravel mining; dams

1950s to 2000s 1950s to 1960s; 1970s to 1990s 1880s to 1920s; 1950s to 1970s Latter 20th century; 1920s to 1990s

Gravel mining; dams Gravel mining; channelization Gravel mining; channelization; dams Gravel mining; channelization; regulation works

1950s to 1990s

Gravel mining; channelization

Channelization Channelization; dams

Liébault and Piégay, 2001, 2002 Suriand and Rinaldi, 2003 Ollero, 2010 Uribelarrea et al., 2003 Segura-Beltrán and Sanchis-Ibor, 2013; Sanchis-Ibor et al., 2017 Zawiejska and Wyzga, 2010 Kiss et al., 2008; Kiss and Blanka, 2012 Sear and Archer (1998); Winterbottom, 2000; Surian and Rinaldi, 2003

warehouses, industrial sites and shopping centres at inadequate distance or next to the riverbanks, in areas historically flooded over the last centuries, increase the vulnerability and the flood risk of the plain. The most urbanized sectors of the floodplain along the last 5 km of the channel are largely classified as high flood risk in the current Master Plan of the Entella River Basin (Regione Liguria, 2018). In the last two centuries the plain has been flooded more frequently (Table 3) than the previous period. The progressive channelization of large segments of the Entella River including the construction of fences and rudimentary levees at the end of the 18th century and concrete levees and later embankments, groynes and other bank protections over the 19th and 20th centuries did not achieve flood risk reduction.

century, and especially over the 20th century. For example, a remarkable retreat of the shoreline are observed along several coasts in Italy (Di Stefano et al., 2013; Acciarri et al., 2016), Greece (Poulos and Chrosni, 2001), Spain (Jabaloy-Sanchez et al., 2010; Del Rio et al., 2013) and North Africa (Fanos, 1995; Aouiche et al., 2016), linked to the increased human disturbance both along watercourses, including channelization, gravel mining, regulation, construction of dams and weirs, etc., which caused a remarkable reduction in fluvial sediment supply, and the coastline, with the construction of ports and marina, seafront walls, fills and embankments, coastal defence structures, etc., that altered the natural equilibrium between the sources of the beach materials and the littoral drift pattern. An interesting result of the historical analysis is the correlation between channel adjustments and flood risk: according to Roccati et al. (2018), the progressive narrowing of the riverbed and the visible reduction in distance between the riverbanks and the built-up areas due to the land-use changes, especially the heavily urbanization of the floodplain during the 20th century, have contributed to increased flood risk. It is evident that the presence of buildings, roads, craft

6. Conclusion Historical analysis has allowed reconstruction of the channel evolution of the Entella River and its floodplain over the last 360 years, from 1656 to 2016. Using a GIS, we calculated the main morphological parameters to evaluate the planform variations of the channel and the 14

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Fig. 10. Curves showing channel widening, sinuosity and shifting changes between 1656 and 2016. Bottom x-axes show the position of the reference points (i.e., points of intersection between the grid of parallel lines at 50 m intervals and the channel centrelines) and their distances, in meters, from the first reference point at Panesi village. Grey areas show the confidence intervals associated to the channel measurements.

European watercourses, and the progressive regression of the coastline, as assessed along other Mediterranean coastal areas. Unlike many previous works in Italy and Europe, we analysed a very long period (i.e., 1656–2016). This fact allowed finer resolution of

shoreline. Results of the quantitative analysis highlights remarkable modifications with a reduction in length, width, sinuosity and shifting consistent with the channel adjustments observed in many Italian and 15

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Fig. 11. Variations of morphological parameters over the 360-years period 1656–2016: (A) channel length, (B) mean channel width, (C) mean and total sinuosity and (D) mean centreline shifting.

channel adjustments by dividing the period into different phases: a first phase characterized by relevant planform changes for the Entella River took place until the end of the 18th century. During this period, human interventions were minimal and the increase in length, width and sinuosity consequent to the gradual westward migration of the channel, and the progradation of the shoreline seem to be correlated substantially to natural morphological processes, i.e., floods and long-shore drift. In the second phase, from the beginning of the 19th century, the gradual increase of human disturbance caused a continuous narrowing of a riverbed, straightening, a reduction in channel length and sinuosity, and a progressive regression of the shoreline, at least until the end of the 20th century. We observed the most substantial modifications during the 20th century, particularly from the 1950s, corresponding to the rapid urban sprawl of the Entella floodplain and the intensive interventions both on the watercourse (i.e., channelization, diversion, sand and gravel quarrying, hydraulic works and construction of bridges, with their up- and down-stream bank protections) and the coastline (construction of ports and marina with fills, embankments and coastal defences). The main effect of these interventions has been a significant reduction in fluvial sediment supply and the disturbance of the natural equilibrium between the sources of the shore materials and the littoral drift pattern. The recent evolutionary trend of the Entella River shows a substantial stability or a slight increase in length and width, correlated to the construction of artificial areas next to the river mouth (ports and associated costal defences) and works carried out to reduce bank erosion and preserve buildings, roads, agricultural and production sites that stand along the riverbanks against floods. Moreover, we analysed the correlation between channel changes and flood risk. Our findings highlight that human disturbance has contributed to increase the flood risk in the plain, with the progressive reduction in width of the riverbed and the increasing anthropic impact along its riverbanks. At the same time, channelization seems to have a negative effect not only on the morphological evolution of the river, but also on the floodplain in terms of risk reduction.

Acknowledgments The research activity is financed by: ARTEMIDE Project (ARchive ThEMatic Imagin Aerophotograf of Events) (http://www.irpi.cnr.it/en/ project/artemide/), supported by Compagnia di San Paolo Italian National Foundation, and ADAPT Project Interreg (http://interregmaritime.eu/web/adapt), co-funded by the Interreg Italy-France Maritime Program 2014–2020, aims to adapt the Italian and French cities of the Upper Tyrrhenian to the consequences of climate change, with particular reference to the urban flash floods caused by intense meteorological phenomena. References Acciarri, A., Bisci, C., Cantalamessa, G., Di Pancrazio, G., 2016. Anthropogenic influence on recent evolution of shorelines between the Conero Mt. And the Tronto R. Mouth (southern Marche, Central Italy). Catena 147, 545–555. https://doi.org/10.1016/j. catena.2016.08.018. Acquaotta, F., Faccini, F., Fratianni, S., Paliaga, G., Sacchini, A., Vilìmek, V., 2018a. Increased flash flooding in Genoa Metropolitan Area: a combination of climate changes and soil consumption? Meteorog. Atmos. Phys. 1–12. https://doi.org/10. 1007/s00703-018-0623-4. Acquaotta, F., Faccini, F., Fratianni, S., Paliaga, G., Sacchini, A., 2018b. Rainfall intensity in the Genoa Metropolitan Area (Northern Mediterranean): secular variations and consequences. Weather 73 (11), 356–362. https://doi.org/10.1002/wea.3208. Aouiche, I., Daoudi, L., Anthony, E.J., Sedrati, M., Ziane, E., Harti, A., Dussouillez, P., 2016. Anthropogenic effects on shoreface and shoreline changes: input from a multimethod analysis, Agadir Bay. Marocco. Geomorphology 254, 16–31. https://doi.org/ 10.1016/j.geomorph.2015.11.013. ARPAL-CMIRL-Agenzia Regionale per la Protezione dell'Ambiente Ligure - Centro Funzionale Meteo-idrologico di Protezione Civile della Regione Liguria, 2003-2010. Annali Idrologici. In: Genova 2003–2010. Available on line: https://www.arpal.gov. it/homepage/meteo/ pubblicazioni/annali-idrologici.html (accessed on 10 January 2019). Aucelli, P.P.C., Rosskopf, C., 2000. Last century valley floor modification of the Trigno River (Southern Italy): a preliminary report. Geogr. Fis. Din. Quat. 23, 105–115.8. Baccino, L., Sanguineti, G., Ascari, M., 1937. Le Spiagge della Riviera Ligure (Reviewed work by H.C.K.H.). Geogr. J. 96 (6), 438–439. https://doi.org/10.2307/1788311. Best, J.L., 1988. Sediment transport and bed morphology at river channel confluences. Sedimentology 35 (3), 481–498. https://doi.org/10.1111/j.1365-3091.1988. tb00999.x. Biggiero, V., Fiorentino, M., Pianese, D., 1994. Evoluzione dell'alveo del Fiume Volturno. In: XXIV Convegno di Idraulica e Costruzioni Idrauliche Vol. II. Bios, Cosenza (T4233-T4-246).

16

Catena 182 (2019) 104122

A. Roccati, et al.

costituzione geologica, suo valore economico: illustrazioni e cartine dimostrative. Tipografia Artistica Colombo, Chiavari. (45 pp). Gurnell, A., Downward, S.R., Jones, R., 1994. Channel planform on the River Dee meanders, 1876-1992. Regul. River. Res. Manage. 9 (4), 187–294. https://doi.org/ 10.1002/rrr.3450090402. Gurnell, A., Surian, N., Zanoni, L., 2009. Multi-thread river channels: a perspective on changing European alpine river systems. Aquat. Sci. 71, 253–265. https://doi.org/10. 1007/s00027-009-9186-2. Hickin, E-J-., Nanson, G.C., 1984. Lateral migration rates or river bands. J. Hydraul. Eng. 110, 11. doi.org/https://doi.org/10.1061/(ASCE)0733-9429(1984)110:11(1557). Issel, A., 1911. L'evoluzione delle rive marine in Liguria. Boll. R. Soc. Geogr. It. 9–12 (112 pp). Jabaloy-Sanchez, A., Lobo, F.J., Azor, A., Barcenas, P., Fernandez-Sala, L.M., del Rio V.D., Perez-Pena J.V., 2010. Human-driven coastline changes in the Adra River deltaic system, southeast Spain. Geomorphology 119(1–2), 9–22. doi.org/https://doi.org/ 10.1016/j.geomorph.2012.02.004. Kiss, T., Blanka, V., 2012. River channel response to climate- and human-induced hydrological changes: case study on the meandering Hernad River, Hungary. Geomorphology 175-176, 115–125. doi.org/https://doi.org/10.1016/j.geomorph. 2012.07.003. Kiss, T., Fiala, K., Sipos, G., 2008. Alterations of channel parameters in response to river regulation works since 1840 on the Lower Tisza River (Hungary). Geomorphology 98(1–2), 96–110. doi.org/https://doi.org/10.1016/j.geomorph.2007.02.027. Lagomaggiore, C., 1912. Il problema del fiume Entella e della spiaggia di ChiavariLavagna. In: Vita Chiavarese. Tipografia Esposito, Chiavari, Italy (64 pp). Lewin, J., Macklin, M.G., Woodward, J.C., 1995. In: Balkema, A.A. (Ed.), Mediterranean Quaternary River Environments. Brookfield, Rotterdam (308 pp). Liébault, F., Piégay, H., 2001. Assessment of channel changes due to long-term bedload supply decrease, Roubion River, France. Geomorphology 36, 167–186. Liébault, F., Piégay, H., 2002. Causes of 20th century channel narrowing in mountain and piedmont rivers of southeastern France. Earth Surf. Process. Landf. 27(4), 425–444. doi.org/https://doi.org/10.1002/esp.328. Lukas, M.C., 2014. Cartographic reconstruction of historical environmental change. Cartographic Perspectives 78, 5–24. doi.org/10.14714/cp78.1218. Magliulo, P., Valente, A., Cartojan, E., 2013. Recent morphological changes of the middle and lower Calore River (Campania, Southern Italy). Env. Earth Sci. 70 (6), 2785–2805. https://doi.org/10.1007/s12665-013-2337-8. Maraga, F., Turconi, L., Pellegrini, L., Anselmo, V., 2015. Scouring in the Po river basin at the upper plain (Italy), in: Lollino, G., Arattano, M., Rinaldi, M., Giustolisi, O., Marechal, J.C., Grant, G. (Eds.), Engineering Geology for Society and Territory. Springer Cham, Switzerland. vol. Volume 3, 489–493. doi.org/10.07/978-3-31909054-2_100. Marchetti, M., 2002. Environmental changes in the central Po Plain (northern Italy) due to fluvial modifications and anthropogenic activities. Geomorphology 44, 361–373. doi.org/https://doi.org/10.1016/s0169-555x(01)00183-0. Meneses, B.M., Reis, E., Pereira, S., Vale, M.J., Reis, R., 2017. Understanding driving forces and implications associated with the land use and land cover changes in Portugal. Sustainability 9, 351. doi.org/https://doi.org/10.3390/su9030351. Micheli, E.R., Larsen, E.W., 2011. River channel cut off dynamics, Sacramenti River, California, USA. River Res. Appl. 27, 3, 328–344. doi.org/https://doi.org/10.1002/ rra.1360. Ministero dei Lavori Pubblici, 1934-2003. Annali Idrologici. Servizio Idrografico di Roma. Ministero di Agricoltura, Industria e Commercio, 1877. Tavole di ragguaglio dei pesi e delle misure già in uso nelle varie province del Regno col Sistema metrico decimale. Stamperia Reale, Rome, Italy. Ollero, A., 2010. Channel changes and floodplain management in the meandering middle Ebro River, Spain. Geomorphology 117 (3–4), 247–260. doi.org/https://doi.org/10. 1016/j.geomorph.2009.01.015. Omodei, D., 1912. Sulle condizioni della spiaggia di Chiavari e Lavagna, con note dei proff. L. De Marchi e A. Issel. R. Comitato Talassografico Italiano, Venezia, (27 pp). Pellegrini, L., Maraga, F., Turitto, O., Audisio, C., Duci, G., 2008. Evoluzione morfologica di alvei fluviali mobili nel settore occidentale del bacino padano. Il Quaternario 21 (1B), 251–266. Perego, S., 1994. Evoluzione naturale e antropica del medio e basso corso del F. Taro (prov. di Parma). Acta Naturalia de l'Ateneo Parmense 30 (1/4), 5–27. Pessagno, G., 1938. Settecento Chiavarese. Atti Società Economica di Chiavari, anno XVI. 41–42. pp. 58–61. Petit, F., Poinsart, D., Bravard, J.P., 1996. Channel incision, gravel mining and bedload transport in the Rhone river upstream of Lyon, France. Catena 26 (3–4), 209–226. doi.org/https://doi.org/10.1016/0341-8162(95)00047-x. Poulos, S., Chrosni, G., 2001. Coastline changes in relation to longshore sediment transport and human impact, alog the shoreline of Kato Achaia (NW Pelopnnese, Greece). Mediterranean Marine Sciences. 2(1), 5–14. doi.org/10.12681/mms.271. Ragazzi, F., Corallo, C., 1981. Chiavari. Sagep, Genova (179 pp.). Regione Liguria, 2018. Piano Stralcio per l'Assetto Idrogeologico. Ambito 16. Carta del Rischio Idraulico. Available online. http://www.pianidibacino.ambienteinliguria.it/ GE/ambito16/tavole/GE_Amb16_RscIdr_03_rev02.pdf, Accessed date: 19 April 2018 (In Italian). Rinaldi, M., 2003. Recent channel adjustments in alluvial rivers of Tuscany, Central Italy. Earth Surf. Process. Land. 28, 587–608. doi.org/https://doi.org/10.1002/esp.464. Rinaldi, M., Simon, A., Billi, P., 1997. Disturbance and adjustments of the Arno River, Central Italy: II. Quantitative analysis of the last 150 years. In: Wang, S.S.Y., Langendoen, E.J., Shields, F.D. (Eds.), Management of Landscapes Disturbed by Channel Incision, Stabilization, Rehabilitation, Restoration. Center for the Computational Hydroscience and Engineering, University of Mississippi, Oxford, MS, pp. 601–606.

Billi, P., Rinaldi, M., 1997. Human impact on sediment yield and channel dynamics in the Arno River basin (central Italy). In: Walling, D.E., Probst, J.L. (Eds.), Human Impact on Erosion and Sedimentation, Proceedings of Rabat Symposium. IAHS, Publication. 245. pp. 301–311. Brandolini, P., Faccini, F., Paliaga, G., Piana, P., 2017. Urban geomorphology in coastal environment: man-made morphological changes in a seaside tourist resort (Rapallo, Eastern Liguria, Italy). Quest. Geogr. 36. https://doi.org/10.1515/quageo-20170027. Canuti, P., Cencetti, C., Conversini, P., Rinaldi, M., Tacconi, P., 1992. Dinamica fluviale recente di alcuni tratti dei fiumi Arno e Tevere. In: Proceeding of the Conference “Fenomni di Erosione e Alluvionamenti Degli Alvei Fluviali”. University of Ancona, pp. 21–35 14-15 October 1991. Capelli, G., Miccadei, E., Raffi, R., 1997. Fluvial dynamics in the Castel di Sangro plain: morphological changes and human impact from 1875 to 1992. Catena 30, 295–309. https://doi.org/10.1016/s0341-8162(97)00008-8. Caporali, E., Rinaldi, M., Casagli, N., 2005. The Arno River floods. G. Geol. Appl. 1, 177–192. https://doi.org/10.1474/gga.2005-01.0-18.0018. Casaretto, F., 2003. Inondazioni a Chiavari dal 1626 al 1950. Monografia. Biblioteca Società Economica, Chiavari, Italy, pp. 1–8. Castaldini, D., Ghinoi, A., 2008. Recent morphological changes of the River Panaro (Northern Italy). Il Quaternario. Ital. J. Quaternary Sci. 21, 267–278. Castaldini, D., Piacente, S., Malmusi, S., 1999. Evoluzione del F. Secchia in pianura nel XIX e nel XX secolo (Province di Reggio Emilia, Modena e Mantova, Italia Settentrionale). In: Orombelli, G. (Ed.), Studi geografici e geologi in onore di Severino Belloni. Glauco Brigati, Genova, pp. 169–187. Clerici, A., Perego, S., Chelli, A., Tellini, C., 2015. Morphological changes of the floodplain reach of the Taro River (Northern Italy) in the last two centuries. J. Hydrol. 527, 1106–1122. https://doi.org/10.1016/j.jhydrol.2015.05.063. Clerici, A., Perego, S., Chelli, A., 2016. Alcuni script di shell per il calcolo e la visualizzazione delle principali caratteristiche morfometriche di un corso d'acqua. In: Geomatics Workbooks. vol. 13 FOSS4G-It: Parma 2016. Comiti, F., Da Canal, M., Surian, N., Mao, L., Picco, L., Lenzi, M.A., 2011. Channel adjustments and vegetation cover dynamics in a large gravel bed river over the last 200 years. Geomorphology 125, 147–159. https://doi.org/10.1016/j.geomorph.2010.09. 011. Conti, S., 1951. Sulle cause determinanti l'arretramento della spiaggia di Chiavari, Lavagna e Cavi. Ann. Ric. St. Geogr. Istituto di Geografia dell'Università di Genova, Genova, Italy. Corradi, N., Delbono, I., Barsanti, M., Morgigni, M., Ferretti, O., 2003. Caratteri morfologici, sedimentologici ed evoluzione del litorale compreso fra Chiavari e Sestri Levante (Liguria orientale). In: Ferretti, O. (Ed.), Studi per la creazione di strumenti di gestione costiera, Golfo del Tigullio. ENEA, Centro Ricerche Ambiente Marino, La Spezia, pp. 21–39. https://doi.org/10.13140/2.1.2513.1528. www.santateresa.enea. it/wwwste/dincost/dincost2.html, Accessed date: 4 January 2019. De Negri, C., 1971. La foce dell'Entella. Note di geografia storica. Estratto da Miscellanea di Geografia Storica e Storia della Geografia, Genova. pp. 21–32. Del Rio, L., Gracia, F.J., Benavente, J., 2013. Shoreline change patterns in sandy coast. A case study in SW Spain. Geomorphology 196, 252–266. https://doi.org/10.1016/j. geomorph.2017.07.027. Del Soldato, M., 1987. L'evoluzione della piana alluvionale del Rupinaro in epoca protostorica e storica. Studi Genuensi 6, 19–45. Di Stefano, A., De Pietro, R., Monaco, C., Zanini, A., 2013. Anthropogenic influence on coastal evolution: a case history from the Catania Gulf shoreline (Eastern Sicily, Italy). Ocean Coast. Manag. 80, 133–148. https://doi.org/10.1016/j.ocecoaman. 2013.02.013. Donadio, C., Vigliotti, M., Valente, R., Stanislao, C., Ivaldi, R., Ruberti, D., 2017. Anthropic vs. natural shoreline changes along the northern Campania coast, Italy. J. Coast. Conserv. 22, 939. https://doi.org/10.1007/s11852-017-0563-z. Downward, S.R., Gurnell, A.M., Brookes, A., 1994. A methodology for quantifying river channel planform change using GIS. In: Variability in Stream Erosion and Sediment Transport: Proceedings of the Canberra Symposium. 224. IAHS Publ, pp. 449–456. Faccini, F., Robbiano, A., Roccati, A., Angelini, S., 2012. Engineering geological map of the Chiavari city area (Liguria, Italy). Journal of Maps 8 (1), 41–47. https://doi.org/ 10.1080/17445647.2012.668756. Faccini, F., Giostrella, P., Lazzeri, R., Melillo, M., Raso, E., Roccati, A., 2015. The 10th November 2014 flash-flood event in Chiavari city (Eastern Liguria, Italy). Rend. Online Soc. Geol. It. 35, 124–127. https://doi.org/10.3301/ROL.2015.80. Faccini, F., Giostrella, P., Melillo, M., Sacchini, A., Santangelo, M., 2017. Heavy rains triggering flash floods in urban environment: a case from Chiavari (Genoa Metropolitan area, Italy). Ital. J. Eng. Geol. Environ. 51–66. https://doi.org/10. 4408/ijege.2017-01.S-05. Fanos, A.M., 1995. The impact of human activities on the erosion and accretion of the Nile coast. J. Coast. Res. 11 (3), 821–833. Fanucci, F., Nosengo, S., 1977. Rapporti tra neotettonica e fenomeni morfogenetici del versante marittimo dell'Appennino Ligure e del margine continentale. Boll. Soc. Geol. It. 96, 41–51. Finnegan, N.J., Roe, G., Montgomery, D.R., Hallet, B., 2005. Controls on the channel width of rivers: implications for modeling fluvial incision of bedrock. Geology 33, 3, 229–232. doi.org/https://doi.org/10.1130/G21171.1. Giustiniani, A., 1854. In: Canepa, V. (Ed.), Annali della Repubblica di Genova, illustrati con note del Porf. Cav. G.B. SPOTORNO. Stabilimento Tipografico Ligustico, Genova, Italy. Gregory, I.N., Ell, P.S., 2007. Historical GIS: Technologies, Methodologies and Scholarship. Cambridge University Press, Cambridge, UK, 978-0-521-85563-1pp. 227. Guarnieri, G.G., 1935. Il bacino fluviale dell'Entella. Suo aspetto morfologico, sua

17

Catena 182 (2019) 104122

A. Roccati, et al.

1016/j.geomorph.2013.06.021. Shields, F.D. Jr, Simon, A. Steffen, L.J., 2000. Reservoir effects on downstream river channel migration. Environ. Conser., 27, 1, 54–66. doi.org/https://doi.org/10.1017/ s0376892900000072. Statuto, D., Cilli, G., Picuno, P., 2017. Using historical maps within a GIS to analyze two centuries of rural landscape changes in southern Italy. Land 6, 65. doi.org/https:// doi.org/10.3390/land6030065. Surian, N., 1999. Channel changes due to river regulation: the case of the Piave River, Italy. Earth Surf. Process. Landforms 24 (12), 1135–1151. doi.org/https://doi.org/ 10.1002/(sici)1096-9837(199911)24:12%3C1135::aid-esp40%3E3.3.co;2-6. Surian, N., 2003. Impatto antropico sulla dinamica recente del Fiume Piave (Alpi Orientali). In: Biancotti, A., Motta, M. (Eds.), Risposta dei processi geomorfologici alle variazioni ambientali. MIUR, Glauco Brigati, Genova, pp. 425–440. Surian, N., Rinaldi, M., 2003. Morphological response to river engineering and management in alluvial channels in Italy. Geomorphology 50, 307–326. doi.org/https:// doi.org/10.1016/s0169-555x(02)00219-2. Surian, N., Rinaldi, M., Pellegrini, L., 2009a. Linee guida per l'analisi geomorfologica degli alvei fluviali e delle loro tendenze evolutive. Cleup, Padova. Surian, N., Ziliani, L., Comiti, F., Lenzi, M.A., Mao, L., 2009b. Channel adjustments and alteration of sediment fluxes in gravel-bed rivers of North-Eastern Italy: potentials and limitations for channel recovery. River Res. Appl. 25, 551–567. https://doi.org/ 10.1002/rra.1231. Uribelarrea, D., Pérez-Gonzalez, A., Benito, G., 2003. Channel changes in the Jarama and Tagus rivers (centrl Spain) over the past 500 years, Quaternary Sci. Rev. 22 (20), 2209–2221. doi.org/https://doi.org/10.1016/S0277-3791(03)00153-7. Winterbottom, S.J., 2000. Medium and short-term channel planform chenges on the Rivers Tay ant Tummel, Scotland. Geomorphology 34 (3–4), 195–208. https://doi. org/10.1016/s0169-555x (00)00007-6. Zawiejska, J., Wyzga, B., 2010. Twentieth-century channel change on thr Dunajec River, southern Poland: patterns, causes and controls. Geomorphology 117 (3–4), 234–246. doi.org/https://doi.org/10.1016/j.geomorph.2009.01.014. Ziliani, L., Surian, N., 2012. Evolutionary trajectory of channel morphology and controlling factors in a large gravel-bed river. Geomorphology 173–174, 104–117. doi. org/https://doi.org/10.1016/j.geomorph.2012.06.001.

Rinaldi, M., Simonici, C., Sogni, D., 2005. Variazioni morfologiche recenti di due alvei ghiaiosi appenninici: il fiume Trebbia e il fiume Vara. Graogr. Fis. Dinam. Quat. (Suppl. VII), 313–319. Rocca, G., 1678. Delle Memorie di Chiavari. Manoscritto conservato presso Società Economica di Chiavari. pp. 123. Roccati, A., Luino, F., Turconi, L., Piana, P., Watkins, C., Faccini, F., 2018. Historical geomorphological research of a Ligurian coastal floodplain (Italy) and its value for management of flood risk and environmental sustainability. Sustainability 10, 3727. doi.org/10.3390/su10103727. Rovereto, G., 1902. Geomorfologia delle coste. Atti Soc. Lig. Sc. Lett 13/14. Rovereto, G., 1939. Liguria geologica. Mem. Soc. Geol. It. 2 (Roma, 734 pp). Sanchis-Ibor, C., Segura-Beltrán, F., Almonacid-Caballer, J., 2017. Channel forms recovery in an ephemera river after gravel mining (Palancia River, Eastern Spain). Catena 15 8357–370. doi.org/https://doi.org/10.1016/j.catena.2017.07.012. Sanguineti, G., 1953. Le alluvioni nel Chiavarese e riassunto meteorologico per l'anno 1953. Tipografia Esposito, Chiavari, Italy, pp. 1–12. Sanguineti, G., 1958. Osservatorio del Seminario di Chiavari. Atti della Società Economica di Chiavari, anno XXVI. Tipografia Esposito, Chiavari, Italy. Schumm, S.A., 1963. Sinuosity of alluvial rivers in the Great Plains. Geol. Soc. Am. Bull. 74, 1089–1100. Scorpio, V., Rosskopf, C.M., 2016. Channel adjustments in a Mediterranean river over the last 150 years in the context of anthropic and natural controls. Geomorphology 275, 90–104. doi.org/https://doi.org/10.1016/j.geomorph.2016.09.017. Scorpio, V., Aucelli, P.P.C., Giano, S.I., Robustelli, G., Rosskopf, C.M., Schiattarella, M., 2015. River channel adjustments in Southern Italy over the past 150 years and implications for channel recovery. Geomorphology 251, 77–90. doi.org/https://doi. org/10.1016/j.geomorph.2015.07.008. Sear, D.A., Archer, D., 1998. Effects of gravel extraction on stability of gravel-bed rivers: The Wooler Water, Northumberland, UK. In: Klimgeman, P.C., Beschta, R.L., Komar, P.D., Bradley, J.B. (Eds.), Gravel-Bed Rivers in the Environment. Water Resources Publications, Highlands Ranch, CO, pp. 415–432. Segura-Beltrán, F., Sanchis-Ibor, C., 2013. Assessment of channel changes in a Mediterranean ephemeral stream since the early twentieth century. The Rambla de Cervera, eastern Spain. Geomorphology 201, 199–214. doi.org/https://doi.org/10.

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