A multi-temporal inventory for constraining earthflow source-to-sink pathways in the Sillaro River basin, Northern Apennines

2020 ◽  
Author(s):  
Sharon Pittau ◽  
Matteo Berti ◽  
Giovanna Daniele ◽  
Marco Pizziolo ◽  
Francesco Brardinoni
Keyword(s):  
River Basin ◽  
Rainfall Variability ◽  
Land Use Changes ◽  
Relevant Information ◽  
Quantitative Information ◽  
Northern Apennines ◽  
Sediment Supply ◽  
Sediment Delivery ◽  
Source To Sink ◽  
Multi Temporal

<p>In mountain environments, landslide sediment supply is one of the main factors that can affect fluvial morphodynamics. In settings underlain by clay-rich lithologies, where earthflows are the dominant agents of hillslope sediment transfer, limited quantitative information is available on the contribution of these processes to the sediment budget. This is a critical aspect both for addressing basic scientific questions on landscape evolution, as well for tackling more applied issues on river sediment management.</p><p>This study focuses on the mountain portion of the Sillaro River basin (138 km<sup>2</sup>), a fluvial system underlain by argillites and siltstones of the Ligurian domain, Northern Apennines (Italy). Here, earthflows are the most common landslide type. Through the compilation of a multi-temporal earthflow inventory (1954-2019), we aim to: (i) characterize earthflow source-to-sink sedimentary pathways, with special reference to sediment delivery to ephemeral and perennial streams; (ii) explore possible litho-topographic controls on earthflow size, frequency and recurrence; (iii) examine historical trend of earthflow activity in relation to rainfall variability and land use changes. Finally, the high and extended temporal resolution of the inventory, will offer the opportunity to test how relevant information could complement the existing inventory of the Emilia-Romagna region, for evaluating earthflow hazard and risk potential.</p><p>Data collection entailed inspection of 12 sequential aerial photo sets (1954, 1969, 1976, 1988, 1996, 2000, 2006, 2008, 2011, 2014, 2016, and 2018), through which earthflows were classified and mapped in GIS environment. This remotely-based activities were complemented by confirmatory field visits on a subset of most recent events. Overall, we have mapped a total of 506 earthflows, which collectively extend over an area of 4.1 km<sup>2</sup>.</p><p>Preliminary results show that earthflow size (i.e., total disturbed area) ranges from 400 m<sup>2</sup> to 98000 m<sup>2</sup>, with frequencies peaking around 10000 m<sup>2</sup>. In terms of source-to-sink pathways, we find that earthflows chiefly tend to deliver sediment to ephemeral gully channels (61%) and perennial tributaries (25%). Whereas, 5% of the events remain on the slopes, and another 5% are buffered by roads and similar anthropogenic barriers. Only a very limited proportion of earthflows (4%) makes it directly to the Sillaro River main stem.</p><p>This work, as part of the projects BEDFLOW and BEFLOW PLUS, is partially funded by Fondazione Cassa di Risparmio in Bologna.</p>

A prototype, high-resolution multi-temporal landslide inventory for the Sillaro River basin, Northern Apennines

2021 ◽  
Author(s):  
Sharon Pittau ◽  
Giovanna Daniele ◽  
Marco Pizziolo ◽  
Francesco Brardinoni
Keyword(s):  
High Resolution ◽  
River Basin ◽  
Google Earth ◽  
Northern Apennines ◽  
Landslide Inventory ◽  
Specific Information ◽  
Disturbed Area ◽  
Multi Temporal ◽  
Emilia Romagna Region ◽  
Sediment Transfer

<p>In mountain environments, landslides are dominant geomorphic processes of sediment transfer and as such, they play a fundamental role in landscape evolution and sediment management at the watershed scale. While monitoring of landslide dynamics at the scale of the single slope failure provides precious site-specific information, an appraisal of landslide-driven sediment dynamics at more representative spatial scales is rarely pursued. In this context, the compilation of multi-temporal, high-resolution landslide inventory represents a challenging but critical task.</p><p>In the Emilia-Romagna region (Italy), landslides cover about the 24% of the hilly and mountain areas within the Northern Apennines. Here, the most common types of landslides are earth slides and earthflows that mainly involve the terrain of clay Ligurian Units and usually are the re-activations of preexisting mass movements. Since the mid ’80, the Geological Survey of Emilia-Romagna Region (RER) has started compiling and updating a region-wide landslide inventory, which includes all movement types, as well as both active (n = 44,377) and dormant (n = 36,608) landforms. The inventory update is customarily performed in selected areas, mainly where landslides have created damages or pose risk to infrastructures, or where ad hoc land planning is needed. In this context, a systematic multi-temporal approach that could provide robust information on landslide occurrence and recurrence is missing.</p><p>To address this gap, in this contribution we propose a multi-temporal inventory prototype, which includes a set of attributes aimed at characterizing landslide sediment transfer across decades. The prototype is developed in the mountain portion of the Sillaro River basin (139 km<sup>2</sup>). The basin is chiefly underlain by argillites of the Ligurian domain, where earth slide and earthflow activity is pervasive.</p><p>The compilation of the multi-temporal landslide inventory is conducted through visual inspection of 10 sequential aerial photo sets (1954, 1969, 1976, 1985-88, 1996, 2000, 2006, 2008, 2011, and 2014), as well as Google Earth satellite imagery (2016 and 2018). In particular, each landslide polygon encloses the total disturbed area, which includes initiation, transport and deposition zones. Polygon planimetric changes are then recorded across sequential photosets. In this way, it is possible to record recurring landslide movements.</p><p>Landslide planimetric geometry includes length, width, and area. Landslide attributes include movement type, photo year of occurrence, morphologic position at initiation (source), and sediment delivery target (sink). Subsequently, for each landslide we subdivide total disturbed area into initiation-transport and deposition polygons. For recurring landslides, we note whether the movement involved: (i) the whole landslide body or only part of it; (ii) headscarp migration; and (iii) advance of the landslide terminus. Finally, we note whether the landslide deposition zone displayed headward incision by means of gully development and/or revegetation.</p><p>This work, as part of the projects BEDFLOW and BEFLOW PLUS, is partially funded by Fondazione Cassa di Risparmio in Bologna.</p>

scholarly journals The influence of changes in flow regime caused by dam closure on channel planform evolution: insights from flume experiments

2021 ◽  
Vol 80 (4) ◽  
Author(s):  
Marcin Słowik ◽  
Kinga Kiss ◽  
Szabolcs Czigány ◽  
Alexandra Gradwohl-Valkay ◽  
József Dezső ◽  
...  
Keyword(s):  
Flow Regime ◽  
Sediment Load ◽  
Land Use Changes ◽  
Sediment Supply ◽  
River Channels ◽  
Flume Experiments ◽  
Sediment Delivery ◽  
Green River ◽  
Single Thread ◽  
Channel Planform

AbstractConstructions of dams influence river courses by cutting off sediment delivery and altering flow regime. We conducted flume experiments to study how sediment starvation, flow deficit and occurrence of series of floods with sediment load influence the evolution of channel planform. Results indicated that reduced flow caused a transition from a braided to incised single-thread planform with remains of inactive channels. The planform resembled rivers suffering from flow reduction caused by dams and constructions of irrigation canals (e.g., Central Platte River, USA). Simulation of series of floods with no sediment delivery caused the formation of an anabranching planform with incised main channel, alluvial islands, and side channels active at high flows. This evolution corresponds to river courses altered by sediment starvation and series of floods (e.g., the lower Drava River, Hungary). Floods with delivery of fines created a single-thread, incised channel with terraces along banks. Such channels are formed by rivers closed by dams, and compensating sediment deficit by sediment load from tributaries and/or floodplains (e.g., the Green River, USA). The flume tests demonstrated how flow and sediment deficit influence river channels and that the potential for restoration strongly depends on possibilities for the activation of sediment supply. However, restoration of pre-dam conditions is often impossible owing to other hydro technical works and land use changes. The highest restoration potential refers to the rivers compensating sediment delivery blocked by dams with tributary and floodplain resources.

scholarly journals Amplified Impact of Climate Change on Fine-Sediment Delivery to a Subsiding Coast, Humboldt Bay, California

2021 ◽  
Author(s):  
Jennifer A. Curtis ◽  
Lorraine E. Flint ◽  
Michelle A. Stern ◽  
Jack Lewis ◽  
Randy D. Klein
Keyword(s):  
Climate Change ◽  
Climate Change Impacts ◽  
Baseline Period ◽  
Climate Impacts ◽  
Sediment Supply ◽  
Balance Model ◽  
Climate Projections ◽  
Sediment Delivery ◽  
Beneficial Reuse ◽  
Coastal Margin

AbstractIn Humboldt Bay, tectonic subsidence exacerbates sea-level rise (SLR). To build surface elevations and to keep pace with SLR, the sediment demand created by subsidence and SLR must be balanced by an adequate sediment supply. This study used an ensemble of plausible future scenarios to predict potential climate change impacts on suspended-sediment discharge (Qss) from fluvial sources. Streamflow was simulated using a deterministic water-balance model, and Qss was computed using statistical sediment-transport models. Changes relative to a baseline period (1981–2010) were used to assess climate impacts. For local basins that discharge directly to the bay, the ensemble means projected increases in Qss of 27% for the mid-century (2040–2069) and 58% for the end-of-century (2070–2099). For the Eel River, a regional sediment source that discharges sediment-laden plumes to the coastal margin, the ensemble means projected increases in Qss of 53% for the mid-century and 99% for the end-of-century. Climate projections of increased precipitation and streamflow produced amplified increases in the regional sediment supply that may partially or wholly mitigate sediment demand caused by the combined effects of subsidence and SLR. This finding has important implications for coastal resiliency. Coastal regions with an increasing sediment supply may be more resilient to SLR. In a broader context, an increasing sediment supply from fluvial sources has global relevance for communities threatened by SLR that are increasingly building resiliency to SLR using sediment-based solutions that include regional sediment management, beneficial reuse strategies, and marsh restoration.

scholarly journals Soil loss risk and habitat quality in streams of a meso-scale river basin

2007 ◽  
Vol 64 (4) ◽  
pp. 336-343 ◽  
Author(s):  
Alexandre Marco da Silva ◽  
Lilian Casatti ◽  
Clayton Alcarde Alvares ◽  
Aline Maria Leite ◽  
Luiz Antonio Martinelli ◽  
...  
Keyword(s):  
River Basin ◽  
Habitat Quality ◽  
Urban Areas ◽  
Riparian Vegetation ◽  
Soil Loss ◽  
Buffer Strips ◽  
Physical Damage ◽  
High Chemical ◽  
Sediment Delivery ◽  
Chemical Purity

Soil loss expectation and possible relationships among soil erosion, riparian vegetation and water quality were studied in the São José dos Dourados River basin, State of São Paulo, Brazil. Through Geographic Information System (GIS) resources and technology, Soil Loss Expectation (SLE) data obtained using the Universal Soil Loss Equation (USLE) model were analyzed. For the whole catchment area and for the 30 m buffer strips of the streams of 22 randomly selected catchments, the predominant land use and habitat quality were studied. Owing mainly to the high soil erodibility, the river basin is highly susceptible to erosive processes. Habitat quality analyses revealed that the superficial water from the catchments is not chemically impacted but suffers physical damage. A high chemical purity is observed since there are no urban areas along the catchments. The water is physically poor because of high rates of sediment delivery and the almost nonexistence of riparian vegetation.

scholarly journals Modeling Land Use Changes and their Impacts on Non-Point Source Pollution in a Southeast China Coastal Watershed

2018 ◽  
Vol 15 (8) ◽  
pp. 1593 ◽  
Author(s):  
Xin Zhang ◽  
Lin Zhou ◽  
Yuqi Liu
Keyword(s):  
Land Use ◽  
Point Source ◽  
River Basin ◽  
Landscape Metrics ◽  
Land Use Changes ◽  
Landscape Patterns ◽  
Cultivated Land ◽  
Point Source Pollution ◽  
Coastal Watershed ◽  
Non Point Source Pollution

Changes in landscape patterns in a river basin play a crucial role in the change on load of non-point source pollution. The spatial distribution of various land use types affects the transmission of non-point source pollutants on the basis of source-sink theory in landscape ecology. Jiulong River basin in southeast of China was selected as the study area in this paper. Aiming to analyze the correlation between changing landscape patterns and load of non-point source pollution in this area, traditional landscape metrics and the improved location-weighted landscape contrast index based on the minimum hydrological response unit (HRULCI) were applied in this study, in combination with remote sensing and geographic information system (GIS) technique. The results of the landscape metrics showed the enhanced fragmentation extent and the decreasing polymerization degree of the overall landscape in the watershed. High values of HRULCI were concentrated in cultivated land, while low HRULCI values mostly appeared in forestland, indicating that cultivated land substantially enhanced non-point source pollution, while forestland inhibited the pollution process.

scholarly journals Water erosion vulnerability and sediment delivery rate in upper Iguaçu river basin – Paraná

RBRH ◽  
2016 ◽  
Vol 21 (4) ◽  
pp. 728-741 ◽  
Author(s):  
Matheus Fonseca Durães ◽  
José Alexandre Pinto Coelho Filho ◽  
Vinícius Augusto de Oliveira
Keyword(s):  
Land Use ◽  
River Basin ◽  
Water Erosion ◽  
Sustainable Land Use ◽  
Delivery Rate ◽  
Sediment Delivery ◽  
Solid Discharge ◽  
Risk Areas ◽  
Gis Environment ◽  
Iguaçu River

ABSTRACT Soil erosion is one of the most striking environmental degradation processes, which its mapping and assessment is an important tool for management activities and natural resource management in river basins, allowing managers to implement policies and sustainable land use occupation. This work aimed to apply the Revised Universal Soil Loss Equation (RUSLE) in a GIS environment in the upper Iguaçu river basin, located at Paraná State, in order to assess the vulnerability to water erosion as well as the concentration of dissolved solids in suspension to estimate the solid discharge and sediment delivery rate, allowing the identification of more susceptible areas to water erosion. The results showed that over 23.52% of the upper Iguaçu river basin presented soil losses below 2.5 t ha–1 yr–1, meaning current low potential for erosion. Regarding the solid discharge, the basin has values ranging from low to very high, also leading to high values for sediment delivery rate. The identification of risk areas associated with accelerated erosion, carried out in this study provide important information for measures associated with the management, conservation and planning of land use in the basin, which is highly relevant for predicting development of various scenarios for the state Paraná for its hydroelectric potential.

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