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Glaciated and recently (post-Little Ice Age) deglaciated areas are very dynamic environments, undergoing continuous changes, in particular as a consequence of climatic fluctuations and cryosphere changes. The intense geomorphic activity that takes place here conditions natural hazard, sediment transport and tourist fruition. A geo-morphological mapping with applicative purposes has to take into account the peculiarities and the dynamism of these specific areas. We here propose a methodological approach based on the interpretation of a multitemporal set of aerial photos (from 1983 to 2012), in a GIS environment, with application to the sectors modeled by Little Ice Age glaciers in the upper Orco Valley (NW Italy). The result is a geo-morphological map focused on the elements that are most relevant for application purposes, complemented by a map of the spatio-temporal distribution of the natural instability processes identified in the study area for the reference period, aimed to highlight the recent dynamism of the geomorphological elements in the map. [ABSTRACT FROM AUTHOR]

In this paper, we present the results of a detailed geomorphological and sedimentological study of a coastal sector of southern Italy, the Pineta della foce del Garigliano SCI (i.e. Site of Community Importance), which is largely affected by shoreline retreat and the degradation of dune habitat. The analysis of shoreline evolution demonstrates that severe erosion processes have occurred over the last 50 years. They caused the complete dismantling of the foredune, whereas the anomalous and advanced position of the secondary dune promoted a progressive loss of vegetation habitat of high environmental value such as juniper (Juniperus oxycedrusssp.macrocarpa). Morpho-sedimentary data and hydrodynamic models suggest that the main climate events promoted a net longshore transport toward the South. Our analyses confirm that erosion processes are linked to natural factors but several negative human practices have contributed to the acceleration of shoreline retreat and degradation of the dune habitat. In addition to its scientific value, the map and data here presented represent an important tool for beach management purposes. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, transport pathways for coarse sediments were studied on an artificial pebble beach located at Marina di Pisa (Tuscany, Italy). Radio frequency identification (RFID) technology was used to trace the pebbles. The RFID technique is an inexpensive and reliable methodology that is used to address sediment displacement along the coastline. The use of low-frequency radio signals (125kHz) enabled the detection of the marked pebbles within a range of 40cm on the underwater and subaerial portions of the beach. About one hundred pebbles were sampled on the beach and paired with passive transponders. The tracers were released along a series of cross-shore transects (March 2009). The pebbles were injected on the fair-weather berm, on the swash zone, and on the step crest along each transect. The recovery campaign was carried out in May 2009. Fifty-three pebbles were detected; this number is rather high given the intensity of the three storms that hit the coast during the period of the experiment and the significant reworking that this beach is subjected to even under fair-weather conditions. The analysis of the tracer pathways highlighted twofold convergent longshore movement on the beach. The trajectories indicated that the longshore movement dominated the cross-shore movement, but there was no prevailing transport direction. To explore the morphology of the sea bottom fronting the beach, a topographic survey was carried out using an echo sounder. The survey showed the presence of two distinct shoals 20m off the coastline that are responsible for the resulting coarse sediment transport. These results confirm that even mild sea bottom irregularities may significantly affect sediment transport dynamics along a beach, suggesting that accurate planning for defense schemes such as artificial coarse replenishment must begin with an in-depth knowledge of the morphology of the sea floor. Such information may increase the durability and/or the efficiency of the intervention. [Copyright &y& Elsevier]

Abstract: Occupation of the coast has significantly increased in recent decades, mostly due to a greater demand for recreation and tourism. Today, erosion threatens many human-made structures and activities, requiring an integrated approach for the understanding of coastal dynamics and identification of alternatives to associated problems. This study investigates a 64km-long coastal physiographic unit in the northern microtidal littoral of Tuscany (Italy). Vertical aerial photographs and direct field surveys were used to retrieve changes in shoreline position over 1938–1997 and 1997–2005 time intervals. Significant beach accretion was observed during the first period updrift of Carrara (84m) and Viareggio (280m) harbours and at Marina di Pietrasanta (100m), whereas severe erosion occurred downcoast of Carrara harbour (−130m, at Marina dei Ronchi) and on the northern side of Arno river mouth (−400m). Similar trends were observed between 1997 and 2005; beach slope between the 1997 shoreline position and the closure depth correlated well with the distribution of erosion/accretion patterns from the 1938–1997 period (slopes were lower in eroded areas than at sites under accretion). Longshore distribution of erosion/accretion patterns was controlled by coastal compartmentalisation. Three of the main littoral cells were mostly formed by natural limits (i.e., Punta Bianca promontory, Marina di Pietrasanta, the Arno river mouth and the port of Livorno). Several sub-cells were created within these cells due to the introduction of human-made structures (such as Carrara and Viareggio harbours), which formed artificial fixed limits that allowed the transport of sediments (exclusively fines) in one direction only. Results will help improve the understanding of coastal processes and manage littoral sediment transport in a sustainable manner. This will reduce the need for structural interventions, such as breakwaters and groynes, which in the past decades prevented coastal retreat at local scale but shifted erosion downdrift, leading to degradation of the investigated area and requiring continuous maintenance. [Copyright &y& Elsevier]

Abstract: Large gravel-bed braided rivers show a highly dynamic evolution, where even moderate flow pulses can produce significant morphological adjustment. An estimation of network variations is needed by river authorities as well as by ecologists for better managing river ecosystems. However, few field investigations have been performed to measure the effect of unsteady discharges in braided rivers. In this paper we report on the morphological changes induced by six different floods in a 1-km-long reach of the Tagliamento River, Italy. Topographic surveys were performed after each significant flood, and an automatic digital camera continuously monitored the planimetric configuration. Repeated measurements of cross section profiles allowed the quantification of the transported sediments volume and, in particular, provided a basis to estimate the percentage of the floodplain subject to morphological evolution. Data analysis showed a good relationship between peak flow level, active width, and mean bed level changes. Similarly, lateral channel shifting is likely to increase for larger floods. Monitoring of a range of discharges up to bankfull conditions revealed a fundamental difference between flow pulses (events on the average occurring one or more times per year) and flood pulses (with a return period larger than two years). The morphological evolution in the former case is mainly limited to a few active branches and is locally driven by bank erosion at the bend apex. On the other hand, larger floods induce a complete reworking of the network configuration, where bifurcations and confluences play a crucial role. Single morphological units (like branches, nodes, bars) are no longer recognizable after this type of event. Braided rivers are therefore characterized by the occurrence of two different spatial and temporal scales that force the ecosystem dynamics. [Copyright &y& Elsevier]

Abstract: This study investigates sediment mobility in a large gravel-bed river (Tagliamento River, northeastern Italy). Field data were used to identify the morphological effectiveness of a range of flows (floods with recurrence interval <1 to 3.5 year) and for a detailed analysis of the partial transport condition. The analyses were carried out on three cross sections where a number of areas representative of different morphological units (main and secondary channels, low and high bars, islands) were painted. Grain size of the painted area was measured using a photographic method. Monitoring of bed mobility during the study period supplied new photographs of the painted areas, measurements of size and travel distance of the mobilized particles, and estimate of flow depth after each flood event. Our analyses have shown that with dimensionless shear stress around 0.073 (17 N m− 2), the morphological effect over the painted areas was primarily partial transport; while with stresses >0.1 (25 N m− 2), the bed experienced full mobility, i.e., all the painted particles were transported or totally buried. Full sediment mobility was observed on lower morphological units (i.e., main and secondary channels) under floods with very high frequency (RI <1 y), whereas on the low bars full mobility occurred under floods with a recurrence interval slightly >1 year. Instead, fine deposition and partial transport conditions were observed on the higher bars even after the largest of the monitored floods (RI =3.5 y). The analysis of the partial transport condition relies on more than 3500 measurements of particle travel distance (travel distances range from a few centimetres up to 22 m). The transported particles were generally finer than the painted sediments, and the analysis of the sediment transport ratio revealed that partial transport occurred under equal-mobility conditions for particles finer than 32 mm and under size-selective mobility for coarser fractions. This appears to be corroborated (for D <32 mm) by the insensitiveness of particle transport distance to particle sizes, even if the exponent (≈1) of the relationship between the dimensionless shear stress and the maximum transported diameter would suggest that all fractions are transported under equal-mobility conditions. [Copyright &y& Elsevier]

Abstract: Among the causes of deep-seated gravitational slope deformations (DGSD), the most important is relief energy, which is closely related to the intensity of the active tectonic deformations, either at the regional scale or at the scale of a single active fault. We analyzed some examples of DGSD from the Eastern border of the Fucino basin, in the Central Apennines, where extensional tectonics has been active since the late Pliocene. Photogeological and field geomorphological analysis was performed to identify landforms typically associated with DGSD, such as counterslope scarps, double crests, trenches, and bulging slopes. These features are located on a mountain range at less than 1 km from the causative fault of the 1915 Avezzano earthquake. We used the SBAS Differential SAR Interferometry technique to measure the slow movements of the surface, and calculated differential vertical and horizontal ground velocities of 2–4 mm yr−1 during the period spanning from 1992 to 2001. The quantitative information on the kinematics of the deformation provided some inferences on the different processes responsible for the evolution of the observed DGSD. The displacement time series shows non-linear deformation trends at some locations, possibly correlated with a strong meteorological event. We speculate that DGSD in this area are normally subject to slow deformation, and that sudden slip along sliding surfaces (observed in excavations) may sporadically be triggered off by extreme meteorological or seismic events. Evidence of catastrophic collapse of previous DGSD along the same mountain slope reinforce this hypothesis. [Copyright &y& Elsevier]

Summary: Coarse sediment transport processes in steep headwater streams may vary between bedload and debris flows events, depending on basin geomorphology and sediment supply. This paper compares two small catchments (drainage area 4–5km2) located in the Eastern Italian Alps where the dominant sediment transport processes differ substantially, i.e., debris flows in the Moscardo Torrent and bedload events in the Rio Cordon. The two basins were selected because they provided the unique opportunity to analyze long-term data of debris flow and bedload volumes, respectively. The two basins are compared in terms of peak discharge, event duration, and magnitude–frequency characteristics of transported sediment volumes. Additional bedload data from two more Alpine experimental basins are also considered. The results show that, for comparable recurrence intervals, debris flow volumes are 2–3 orders of magnitude larger than bedload volumes. This contrasting sediment transfer activity can be attributed to different basin and channel morphologies, which are analyzed in terms of sediment supply conditions, longitudinal profiles and slope–area curves. [Copyright &y& Elsevier]

In the present work on-going research is discussed whose primary goal is to test some statistical methods to estimate the average yearly area-specific sediment yield (SSY). Using geomorphological and climatic parameters various multiple regression formulae have been set up based on SSY observed data from 16 catchments of Sicily. Three distinct techniques were adopted to select the parameters to be used in the equations: simple correlation, stepwise regression analysis and a supervised geomorphological–statistical correlation. The comparison of the results showed the effectiveness of the stepwise analysis, which led to a regression equation with a coefficient of determination ( r 2) of 0.87. Nevertheless, even this methodology showed some elements of uncertainty that have caused, in some cases, appreciable differences between observed and predicted values (mean percentage error equal to 26%). These differences are likely either due to the hydraulic regime of most of Sicilian watercourses (typical of semi-arid regions) or to hidden factors (e.g., topography, human impact and concentrated erosion), which can greatly affect the processes of sediment production and transport. The study has pointed out the need to take into account a larger number of observations and to perform the analysis of relations between suitable variables and SSY at a more detailed time resolution. [ABSTRACT FROM AUTHOR]

Studying fluvial dynamics and environments, GIS-based analyses are of fundamental importance to evaluate the network geometry and possible anomalies, and can be particularly useful to estimate modifications in processes and erosion rates. The aim of this paper is to estimate short-term erosion rates attributable to fluvial processes in two sample catchment sub-basins of the Marecchia river valley, by conducting quantitative morphometric analyses in order to calculate various descriptive parameters of the hierarchisation of the river networks and the mean turbid transport of streams (Tu). Sediment yield transported by streams can in fact partially express the amount of erosional processes acting within the drainage basin. The study area includes two sub-basins of the Marecchia valley (Senatello river, 49 km2 and Mazzocco river, 47 km2), chosen because of their similar extent and of the different location in the major catchment basin. Starting from geomorphological maps of the two river basins, the Tu parameter has been calculated and converted in short-term rate (average value 0.21 mm/year). Moreover, the comparison of these short-term mean data with the uplift rates calculated on a regional scale (0.41 ± 0.26 mm/year) in the Marecchia valley confirms that the northern Apennines may represent a non-steady state system. [ABSTRACT FROM AUTHOR]