Cascading processes of the Vaia storm in the italian Rio Cordon mountain catchment

<p>Mountain basins can be affected by Large Infrequent Disturbances (LIDs) that have the power of changing their forest cover and morphological settings, and supplying high amounts of sediments to river networks. The resulting cascading processes are often underestimated although their understanding would improve river management strategies. The recent improvements in the field of sediment transport monitoring and analysis allow to gather a deeper understanding of these long-lasting and complex chains of processes, especially in mountain streams. This contribution aims at investigating the suspended sediment transport exhibited by two recent (summer-autumn 2020) over-bankfull (> 2.3 m<sup>3</sup>/s) flood events occurred in the Rio Cordon, an alpine basin (5 km<sup>2</sup>) strongly altered by the Vaia storm (October 2018). This LID blew down 139 trees along the main active channel that were removed by local forest operations after the event, leaving exposed banks and increasing the availability of fine sediment. Two water quality sondes were placed upstream and downstream the windthrow affected area (WAA) to monitor the Suspended Sediment Load (SSL) and quantify the contribution of the WAA in supplying sediments. Water discharge and suspended sediment transport were continuously measured by the two instrumentations, while water samples and direct discharge measurements (salt dilution method) were taken to derive rating curves and calibrate the turbidity meters. Results show that the early September 2020 event (Q<sub>max</sub>=2.67 m<sup>3</sup>/s) produced a SSL = 39.27 t and a SSL increase of +5% between the downstream and upstream cross-section. To this, it was also registered a +44% variation of SS maximum concentration (SSC g/l) which can be ascribed to the contribution of the WWA. The event of October 2020 (Q<sub>max</sub>=3.05 m<sup>3</sup>/s) instead, registered a SSL of 179.22 t and a SSL and SSC<sub>max</sub> variation of +334% and +81%, respectively. The preliminary results suggest that the SS is not related to the water discharge but for this reason, further analysis and data collection will be made, also considering rainfall data. However, the ongoing monitoring of this area represents a suitable and promising approach for understanding the cascading processes on the SS dynamics in a mountain basin affected by a LID.</p>

Beyond Sugar and Ethanol Production: Value Generation Opportunities Through Sugarcane Residues

Sugarcane is the most produced agricultural commodity in tropical and subtropical regions, where it is primarily used for the production of sugar and ethanol. The latter is mostly used to produce alcoholic beverages as well as low carbon biofuel. Despite well-established production chains, their respective residues and by-products present unexploited potentials for further product portfolio diversification. These fully or partially untapped product streams are a) sugarcane trash or straw that usually remain on the fields after mechanized harvest, b) ashes derived from bagasse combustion in cogeneration plants, c) filter cake from clarification of the sugarcane juice, d) vinasse which is the liquid residue after distillation of ethanol, and e) biogenic CO2 emitted during bagasse combustion and ethanol fermentation. The development of innovative cascading processes using these residual biomass fractions could significantly reduce final disposal costs, improve the energy output, reduce greenhouse gas emissions, and extend the product portfolio of sugarcane mills. This study reviews not only the state-of-the-art sugarcane biorefinery concepts, but also proposes innovative ways for further valorizing residual biomass. This study is therefore structured in four main areas, namely: i) Cascading use of organic residues for carboxylates, bioplastic, and bio-fertilizer production, ii) recovery of unexploited organic residues via anaerobic digestion to produce biogas, iii) valorization of biogenic CO2 sources, and iv) recovery of silicon from bagasse ashes.

Assessment Principles for Glacier and Permafrost Hazards in Mountain Regions

Glacier and permafrost hazards encompass various flood and mass movement processes that are directly conditioned or triggered by contemporary changes in the alpine cryosphere, threatening lives and livelihoods in most mountain regions of the world. These processes are characterized by a range of spatial and temporal dimensions, from small-volume icefalls and rockfalls that present a frequent but localized danger, to less frequent but larger-magnitude avalanches of ice and/or rock and related process chains that can travel large distances and thereby threaten people and infrastructure located far downstream. Glacial lake outburst floods (GLOFs) have proven particularly devastating, accounting for the most far-reaching disasters in high mountain regions globally. GAPHAZ, the Standing Group on Glacier and Permafrost Hazards of the International Association of Cryospheric Sciences (IACS), and the International Permafrost Association (IPA) recently published a technical guidance document on the assessment of glacier and permafrost hazards in mountain regions, drawing on internationally accepted best practices of integrated hazard assessment, reflecting the scientific state of the art. Here, the main aspects of this guidance document are summarized and reflected in the context of the historic development, current state, and future challenges related to the assessment of glacier- and permafrost-related hazard assessments. In a comprehensive assessment of glacier and permafrost hazards, two core components (or outcomes) are typically included: 1. Susceptibility and stability assessment: Identifying where from, and how likely an event could be, based on analyses of wide-ranging triggering and conditioning factors driven by interlinking atmospheric, cryospheric, geological, geomorphological, and hydrological processes. 2. Hazard mapping: Identifying the potential impact on downslope and downstream areas through a combination of process modeling and field mapping, providing the scientific basis for decision-making and planning. Glacier and permafrost hazards gained prominence around the mid-20th century, especially following a series of major disasters in the Peruvian Andes (Huaraz, 1941, and the Huascarán events of 1962 and 1970), Alaska (Lituya Bay, 1958), and the Swiss Alps (Mattmark, 1965). At the time of these events, related hazard assessments were reactionary and event-focused, aiming to understand the causes of the disasters and assess the ongoing threat to communities. These disasters, and others that followed (e.g., Kolka–Karmadon, 2002), established the fundamental need to consider complex geosystems and cascading processes with their cumulative downstream impacts as one of the distinguishing principles of integrative glacier and permafrost hazard assessment. Nowadays, the widespread and free availability of satellite imagery enables a pre-emptive approach to hazard assessment, beginning with regional-scale first-order susceptibility, hazard assessment, and modeling that provide a first indication of possible unstable slopes or dangerous lakes and related cascading processes. Detailed field investigations and scenario-based hazard mapping can then be appropriately targeted to high-priority areas. In view of the rapidly changing mountain environment, leading beyond historical precedence, there is a clear need for future-oriented scenarios to be integrated into the hazard assessment, considering, for example, the threat from new lakes that are projected to emerge in a continuously deglaciating landscape. In particular, low-probability events with extreme magnitudes are a challenge for authorities to plan for, but such events can be appropriately considered as worst-case scenarios in a comprehensive, forward-looking, multi-scenario hazard assessment.

Exploring the Space of Possibilities in Cascading Disasters with Catastrophe Dynamics

Some of the most devastating natural events on Earth, such as earthquakes and tropical cyclones, are prone to trigger other natural events, critical infrastructure failures, and socioeconomic disruptions. Man-made disasters may have similar effects, although to a lesser degree. We investigate the space of possible interactions between 19 types of loss-generating events, first by encoding possible one-to-one interactions into an adjacency matrix A, and second by calculating the interaction matrix M of emergent chains-of-events. We first present the impact of 24 topologies of A on M to illustrate the non-trivial patterns of cascading processes, in terms of the space of possibilities covered and of interaction amplification by feedback loops. We then encode A from 29 historical cases of cascading disasters and compute the matching matrix M. We observe, subject to data incompleteness, emergent cascading behaviors in the technological and socioeconomic systems, across all possible triggers (natural or man-made); disease is also a systematic emergent phenomenon. We find interactions being mostly amplified via two events: network failure and business interruption, the two events with the highest in-degree and betweenness centralities. This analysis demonstrates how cascading disasters grow in and cross over natural, technological, and socioeconomic systems.

Landslides and other damage to buildings and infrastructures following the April–May 2015 earthquake sequence, Solukhumbu District, Eastern Nepal

The study focuses on the eastern margin of the zone affected by the April–May 2015 earthquakes, i.e. the Dudh Koshi River section between the Khari Khola and Monjo (Solukhumbu District). Visits before and after the earthquake sequence allowed us to assess the geomorphic changes caused by the earthquakes and the subsequent monsoon. These changes are characterized by land sliding (rock falls, rockslides, landslides, gullies and debris flows), and cascading processes, which supplied coarse debris into rivers (bed load).The impact of the earthquakes on buildings, trails and existing infrastructures (canals, hydropower plants) was also investigated. While the age and construction quality of buildings are of some import, other parameters such as the nature and depth of colluvial deposits appear to be significant factors likely to amplify the effects of ground shaking, as observed on large block fields south-west of the Khari Khola catchment, which might be inherited from former undated seismic events.