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2 pages, 154 KiB

Open AccessEditorial

Editorial for Quantitative Geomorphology Special Issue

by Dario Gioia

Geosciences 2018, 8(12), 475; https://doi.org/10.3390/geosciences8120475 - 12 Dec 2018

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Abstract

In recent years, DEM- and GIS-supported analysis of landscape has become an important research field in many geomorphological applications, which aim to model surface processes in a variety of geomorphic environments and at different spatial and temporal scales. [...] Full article

(This article belongs to the Special Issue Quantitative Geomorphology)

Research

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20 pages, 16459 KiB

Open AccessArticle

Origin of Knickpoints in an Alpine Context Subject to Different Perturbing Factors, Stura Valley, Maritime Alps (North-Western Italy)

by Monica Marrucci, Gerold Zeilinger, Adriano Ribolini and Wolfgang Schwanghart

Geosciences 2018, 8(12), 443; https://doi.org/10.3390/geosciences8120443 - 28 Nov 2018

Cited by 16 | Viewed by 6646

Abstract

Natural catchments are likely to show the existence of knickpoints in their river networks. The origin and genesis of the knickpoints can be manifold, considering that the present morphology is the result of the interactions of different factors such as tectonic movements, quaternary [...] Read more.

Natural catchments are likely to show the existence of knickpoints in their river networks. The origin and genesis of the knickpoints can be manifold, considering that the present morphology is the result of the interactions of different factors such as tectonic movements, quaternary glaciations, river captures, variable lithology, and base-level changes. We analyzed the longitudinal profiles of the river channels in the Stura di Demonte Valley (Maritime Alps) to identify the knickpoints of such an alpine setting and to characterize their origins. The distribution and the geometry of stream profiles were used to identify the possible causes of the changes in stream gradients and to define zones with genetically linked knickpoints. Knickpoints are key geomorphological features for reconstructing the evolution of fluvial dissected basins, when the different perturbing factors affecting the ideally graded fluvial system have been detected. This study shows that even in a regionally small area, perturbations of river profiles are caused by multiple factors. Thus, attributing (automatically)-extracted knickpoints solely to one factor, can potentially lead to incomplete interpretations of catchment evolution. Full article

(This article belongs to the Special Issue Quantitative Geomorphology)

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17 pages, 7821 KiB

Open AccessArticle

Landslide Disasters Triggered by Extreme Rainfall Events: The Case of Montescaglioso (Basilicata, Southern Italy)

by Maurizio Lazzari and Marco Piccarreta

Geosciences 2018, 8(10), 377; https://doi.org/10.3390/geosciences8100377 - 15 Oct 2018

Cited by 44 | Viewed by 4777

Abstract

We present the results of the study of a large and rapid landslide disaster event, which occurred in Montescaglioso, southern Italy, on 3 December 2013. The studied landslide developed following extreme rainfalls in a zone characterized by a stabilized paleo-landslide body and anthropized [...] Read more.

We present the results of the study of a large and rapid landslide disaster event, which occurred in Montescaglioso, southern Italy, on 3 December 2013. The studied landslide developed following extreme rainfalls in a zone characterized by a stabilized paleo-landslide body and anthropized in time, filling some streams of the original hydrographic network. The morpho-topographic setting characterizing the slope before the new landslide, has showed, in fact, a substantial stability confirmed also by the application of SINMAP (Stability Index MAPping) analysis. Nevertheless, heavy rains and floods caused a powerful and spectacular landslide event because of the anthropic removal of the old drainage network, which has caused the heaviness of the slope located upstream of the 20 collapsed buildings and along the ill-drained quick-road, built transversely to the slope. Full article

(This article belongs to the Special Issue Quantitative Geomorphology)

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19 pages, 8406 KiB

Open AccessArticle

A Study on Variation in Channel Width and Braiding Intensity of the Brahmaputra River in Assam, India

by Jogendra Nath Sarma and Shukla Acharjee

Geosciences 2018, 8(9), 343; https://doi.org/10.3390/geosciences8090343 - 11 Sep 2018

Cited by 29 | Viewed by 10616

Abstract

The Brahmaputra River flows through Assam, India, for about 670 km along an alluvial valley as a wide braided river. The width of the river varies with time along its course. The braiding intensity of this river is estimated using the braiding index [...] Read more.

The Brahmaputra River flows through Assam, India, for about 670 km along an alluvial valley as a wide braided river. The width of the river varies with time along its course. The braiding intensity of this river is estimated using the braiding index (BI) of Brice (1964), which also changes with space and time along the course of the river. Temporal changes of both width and BI have been studied using topographic maps of 1912–1928 and 1963–1975, and dry season satellite data of 1996, 2000, 2007 and 2009. The mean widths of the Brahmaputra River channel in Assam during 1912–1928, 1963–1975, 1996, 2000, 2007 and 2009 were 5949 m, 7455 m, 7505 m, 8008 m, 8308 m and 9012 m, respectively, confirming an overall increase in width with time. Both the width and variation of width are lowest in four short narrower segments of the river. Three of these segments represent hard points comprising gneissic rock, and one segment is on alluvium comprising cohesive clay. The increase in width is correlated to enormous sediment load produced by the great Assam earthquake of 1950 and large-scale deforestation in the Himalayas. The mean BIs for the Brahmaputra for 1963–1975, 1996, 2000, 2007 and 2009 were 8.59, 8.43, 6.67, 6.58 and 7.70, respectively, indicating in general a decreasing trend up to 2007. The BI showed low variation at the four narrow segments where there is also a minimum variation of the channel width. The BI has increased significantly in the upstream part of the river. Very high fluctuation of discharge (17,000

m^{3} / s^{- 1}

in 24 h) and high sediment loads of the Brahmaputra (daily mean sediment discharge of 2.0 million tonnes during monsoon), erodible alluvial banks and high width/depth ratios are the main causes of development of braiding. The interrelationship between channel width and BI of the Brahmaputra shows a positive correlation, indicating an increase in BI with increasing channel width. Full article

(This article belongs to the Special Issue Quantitative Geomorphology)

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19 pages, 9701 KiB

Open AccessArticle

Right-Angle Pattern of Minor Fluvial Networks from the Ionian Terraced Belt, Southern Italy: Passive Structural Control or Foreland Bending?

by Dario Gioia, Marcello Schiattarella and Salvatore Ivo Giano

Geosciences 2018, 8(9), 331; https://doi.org/10.3390/geosciences8090331 - 3 Sep 2018

Cited by 22 | Viewed by 3611

Abstract

Morphometric analyses of both the topography and drainage network have been carried out in a large sector of the Ionian coastal belt of southern Italy in order to unravel the possible control of Late Quaternary thrust front activity on the evolution of the [...] Read more.

Morphometric analyses of both the topography and drainage network have been carried out in a large sector of the Ionian coastal belt of southern Italy in order to unravel the possible control of Late Quaternary thrust front activity on the evolution of the fluvial net. The study area extends in the southernmost sector of the Bradano Foredeep and is featured by several orders of uplifted marine terraces, ranging in age from Middle Pleistocene to Late Quaternary. The flight of the marine terraces is deeply cut by a trellis-type and regularly spaced minor fluvial network. Morphotectonic investigations based on field survey, photo-aerial interpretation, topographic attributes, morphometric indices, and analysis of longitudinal river profiles suggest a strong control on the drainage network arrangement by a pervasive orthogonal fracture system, produced and preserved into the brittle caprock of the terraces, made by conglomerate. Since a similar pervasive and orthogonal fracture pattern is typically generated by gentle folding of rocks, the development of the Ionian hydrographic networks could be attributed to a general—maybe still active—bending of the foredeep area due to the eastward propagation of blind thrusting of the Apennines orogenic chain. Full article

(This article belongs to the Special Issue Quantitative Geomorphology)

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19 pages, 5099 KiB

Open AccessArticle

Objective Regolith-Landform Mapping in a Regolith Dominated Terrain to Inform Mineral Exploration

by Alicia S. Caruso, Kenneth D. Clarke, Caroline J. Tiddy, Steven Delean and Megan M. Lewis

Geosciences 2018, 8(9), 318; https://doi.org/10.3390/geosciences8090318 - 24 Aug 2018

Cited by 13 | Viewed by 8007

Abstract

An objective method for generating statistically sound objective regolith-landform maps using widely accessible digital topographic and geophysical data without requiring specific regional knowledge is demonstrated and has application as a first pass tool for mineral exploration in regolith dominated terrains. This method differs [...] Read more.

An objective method for generating statistically sound objective regolith-landform maps using widely accessible digital topographic and geophysical data without requiring specific regional knowledge is demonstrated and has application as a first pass tool for mineral exploration in regolith dominated terrains. This method differs from traditional regolith-landform mapping methods in that it is not subject to interpretation and bias of the mapper. This study was undertaken in a location where mineral exploration has occurred for over 20 years and traditional regolith mapping had recently been completed using a standardized subjective methodology. An unsupervised classification was performed using a Digital Elevation Model, Topographic Position Index, and airborne gamma-ray radiometrics as data inputs resulting in 30 classes that were clustered to eight groups representing regolith types. The association between objective and traditional mapping classes was tested using the ‘Mapcurves’ algorithm to determine the ‘Goodness-of-Fit’, resulting in a mean score of 26.4% between methods. This Goodness-of-Fit indicates that this objective map may be used for initial mineral exploration in regolith dominated terrains. Full article

(This article belongs to the Special Issue Quantitative Geomorphology)

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13 pages, 3711 KiB

Open AccessFeature PaperArticle

Generation of Persistent Scatterers in Non-Urban Areas: The Role of Microwave Scattering Parameters

by Giovanni Nico, Sérgio C. Oliveira, Joao Catalão and José Luis Zêzere

Geosciences 2018, 8(7), 269; https://doi.org/10.3390/geosciences8070269 - 23 Jul 2018

Cited by 4 | Viewed by 3090

Abstract

In this work, we study the capability of the ground surface to generate Persistent Scatterers (PS) based on the lithology, slope and aspect angles. These properties affect the scattering behavior of the Synthetic Aperture Radar (SAR) signal, the interferometric phase stability and, as [...] Read more.

In this work, we study the capability of the ground surface to generate Persistent Scatterers (PS) based on the lithology, slope and aspect angles. These properties affect the scattering behavior of the Synthetic Aperture Radar (SAR) signal, the interferometric phase stability and, as a consequence, the PS generation. Two-time series of interferometric SAR data acquired by two different SAR sensors in the C-band are processed to generate independent PS datasets. The region north of Lisbon, Portugal, characterized by sparse vegetation and lithology diversity, is chosen as study area. The PS frequency distribution is obtained in terms of lithology, slope and aspect angles. This relationship could be useful to estimate the expected PS density in landslide-prone areas, being lithology, slope and aspect angles important landslide predisposing factors. Full article

(This article belongs to the Special Issue Quantitative Geomorphology)

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19 pages, 2776 KiB

Open AccessArticle

Investigating the Sediment Yield Predictability in Some Italian Rivers by Means of Hydro-Geomorphometric Variables

by Sergio Grauso, Francesco Pasanisi, Carlo Tebano, Marcello Grillini and Alessandro Peloso

Geosciences 2018, 8(7), 249; https://doi.org/10.3390/geosciences8070249 - 5 Jul 2018

Cited by 10 | Viewed by 3618

Abstract

In the present work, preliminary results are reported from an ongoing research study aimed at developing an improved prediction model to estimate the sediment yield in Italian ungauged river basins. The statistical correlations between a set of hydro-geomorphometric parameters and suspended sediment yield [...] Read more.

In the present work, preliminary results are reported from an ongoing research study aimed at developing an improved prediction model to estimate the sediment yield in Italian ungauged river basins. The statistical correlations between a set of hydro-geomorphometric parameters and suspended sediment yield (SSY) data from 30 Italian rivers were investigated. The main question is whether such variables are helpful to explain the behavior of fluvial systems in the sediment delivery process. To this aim, a broad set of variables, simply derived from digital cartographic sources and available data records, was utilized in order to take into account all the possible features and processes having some influence on sediment production and conveyance. A stepwise regression analysis pointed out that, among all possibilities, the catchment elevation range (H_r), the density of stream hierarchical anomaly (D_a), and the stream channel slope ratio (ΔS_s) are significantly linked to the SSY. The derived linear regression model equation was proven to be satisfactory (r²-adjusted = 0.72; F-significance = 5.7 × 10⁻⁸; ME = 0.61), however, the percentage standard error (40%) implies that the model is still affected by some uncertainties. These can be justified, on one hand, by the wide variance and, on the other hand, by the quality of the observed SSY data. Reducing these uncertainties will be the effort in the follow-up of the research. Full article

(This article belongs to the Special Issue Quantitative Geomorphology)

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19 pages, 9869 KiB

Open AccessArticle

Beach Erosion in the Gulf of Castellammare di Stabia in Response to the Trapping of Longshore Drifting Sediments of the Gulf of Napoli (Southern Italy)

by Micla Pennetta

Geosciences 2018, 8(7), 235; https://doi.org/10.3390/geosciences8070235 - 27 Jun 2018

Cited by 11 | Viewed by 5582

Abstract

The results of this study have allowed verification that longshore sediment transport along the coast of Napoli Gulf (southern Italy) takes place from Northwest to Southeast. The current analysis describes the results of an integrated sedimentological and geomorphological study of the Neapolitan coastal [...] Read more.

The results of this study have allowed verification that longshore sediment transport along the coast of Napoli Gulf (southern Italy) takes place from Northwest to Southeast. The current analysis describes the results of an integrated sedimentological and geomorphological study of the Neapolitan coastal area. A sedimentological and morphosedimentary study was carried out by bathymetric survey and sampling of bottom sediments. The analysis of modal isodensity curves shows that all the sediments are moved from NW to SE by longshore currents parallel to the coastline. The morphological evolution of the Castellammare di Stabia Gulf coastal area, based on historical coastline changes, starts from 1865, when the sandy littoral was wide and in its natural state. Since the construction of the Torre Annunziata harbor in 1871, sediments transported by a NW-SE longshore drift have become trapped, inducing the genesis of a new wide triangular-shaped beach on the updrift side (NW) of the harbor breakwall. This process induced a significant shoreline retreat of the south-east sector of the littoral. Widespread beach erosion of the coastal physiographic unit of Castellammare di Stabia Gulf (delimited by two ports) is more developed in the southern portion. This study highlights a slight rotation of the shoreline toward the East and a general trend of regression, with typical overall accentuation of shoreline concavity, and significant widening of the triangular-shaped beaches at the end of the falcate. This reduced sediment input removed from the sedimentary budget a large amount of deposits, which are hardly restorable due to the scarce supply of sediment load by the Sarno river and its tributaries. In addition to this new and important derived morphologic feature, other recent human interventions have contributed to further modifications of morphologic characteristics of emerged and submerged beach. The intense use of the territory caused modifications on both the fluvial course and river mouth with direct and indirect effects on the shoreline and the drainage network of the Sarno River. Full article

(This article belongs to the Special Issue Quantitative Geomorphology)

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