Hillslope degradation in representative Italian areas: Just soil erosion risk or opportunity for development?

Abstract

In recent years, much research have dealt with the impact of human and climate change on the morpho-evolution of Mediterranean catchments characterized by high ecological and cultural value. In this paper, we speculated how humans can influence hillslope degradation by reviewing the relationships between denudation processes and land use changes in some representative areas located in different Italian regions (i.e., Liguria, Tuscany, Basilicata, and Sicily). The selected study cases are characterized by different climatic and geological features, land use, and land management and can be considered indicative of the hillslope degradation issues that affected the Apennines during the last century. We compared and discussed the main outcomes from previous studies, with the aim of identifying the main drivers leading to hillslope degradation and to shed light on the role of human action. We revealed that hillslope degradation can be mainly related to deforestation for land reclamation, cropland abandonment, and the increase of hazardous rainfall. Moreover, we focused on how human impact can have both positive and negative feedbacks. In some cases (e.g., badlands), the land levelling has produced an initial inhibition of land degradation, whereas after intensive agricultural practices, accelerated soil depletion has occurred, favouring erosion processes. Analogously, terracing controlled erosion as long as the entire terrace system was maintained, but abandoned terraced slopes can increase the magnitude of geo-hydrological phenomena in response to high-intensity rainfall.On-the-other-hand, both rural landscape and related erosional landforms can be appreciated as elements of landscape diversity and contribute to tourism development.

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

“…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…”

“…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].…”

Land Use, Internal Mobility and External Immigration in Italy

“…Rural areas in Italy are characterized by a strong presence of mountain landscape. 16 On the Apennine Mountains, moreover, towns are often at the top of high hills: the reasons are both geographical and historical; the Country has like a backbone the Apennines, which are not far from the sea. In Italy almost 60% of the national territory should be considered mountain or hilly rural areas but just a little more of 20% of the population live in this large part of the Country.…”

“…It is possible therefore to realize a sharp difference between mountain areas in Alps and in the Apennines and different patterns of governance of rural development have been enacted; governance of integration of immigrants also has not been uniform, but it can contribute to give inner and mountain areas a more balanced demographic and economic asset. 16 There is a fundamental difference between inner and mountain area as rightly pointed by G. Dematteris, "La Montagna nella Strategia per le aree interne 2014-2020," in Agriregioni Europa, n. 9, 2013. Specific policies for mountain areas inside the broader strategy for inner areas should be taken in account.…”

“…It must be considered, anyway, that in Italy the mountain and hilly areas represent most of the inner areas. For a broad overview of the characteristics of Italian soils, see also Morari (2016) and for the impact of land use changes on hillslope degradation see Brandolini et al (2018). 17 A report on mountain areas with statistical data is issued by the Foundation on Mountains.…”