1,721,047 research outputs found
Characterizing governance and benefits of payments for watershed services in Europe
Full text linkGlobally, Payments for Watershed Services (PWS) make-up the largest ecosystem service market (Bennett et al., 2014b). Driven by the negative impacts of climate change and economic development for water quantity and quality provision, hydrological services are assuming a leading priority among forest and agriculture-based ecosystems. Indeed, afforestation and sustainable agriculture tend to be among the most rewarded management practices under contracts aiming to achieve additionality in upstream water storage, water quality protection and flood risk mitigation. Although conventionally PES is seen as a market-based tool, most existing PWS in Europe fundamentally depend on public bodies that act as intermediaries. European PWS are thus best described as “PES-like” schemes implemented by public entities, often acting in a rather complex institutional framework (Vatn, 2010). Accordingly, the research to date has tended to focus mainly on analyzing case studies from developing countries and US rather than Europe (Schomers and Matzdorf, 2013).
Through a snowball approach and networking, the study provided the first most comprehensive inventory of PWS case studies in Europe. We then used the 76 case studies for a comparative analysis aimed to characterize institutional, economic and governance mechanisms associated with PWS in Europe. Besides, we conducted a more detailed institutional analysis of four selected case studies in Italy and England.
The results show how co-investment approaches, public procurement and collaborative partnerships are substituting the theoretical idea of market transactions and commoditization of ecosystem services.
Long-term durability of private driven PWS depends on the ability of integrating different sources of funding, starting from existing subsides, private investments and service beneficiaries funds. We found evidence that innovative governance models based on partnership may increase PWS success by developing schemes with a clear benefits related to social, carbon and biodiversity. Ensuring PWS related co-benefits is important in order to engage and have a positive actors’ interaction, thus increase capacity and scale through partnerships and cross-cutting institutions. Collaborative approaches provide better territorial coverage, technical and financial capacity that has showed to be a key factor for PWS success.
Regarding public schemes, PWS based on public budget allocation are often undermined by political instability that could affect the allocation of resources depending on availability and political decisions. To avoid instability public PWS should be coupled with regulations that set financial instruments such as water charges or funds that systematically raise financial sources to run the scheme. Considered schemes based on water charges are run on long-term and seemed to have bigger scale and impactsI Pagamenti per i Servizi Ecosistemici nel settore idrico (PWS, dall’inglese Payments for Watershed Services) costituiscono il mercato dei servizi ecosistemici più grande al mondo (Bennett et al., 2014b). I servizi idrologici stanno via via assumendo un ruolo di primo piano nella gestione degli ecosistemi agricoli e forestali, in modo particolare per contrastare gli effetti del cambiamento climatico e dello sviluppo economico sulla qualità e quantità della risorsa idrica.
Infatti, il rimboschimento e le pratiche di agricoltura sostenibile tendono ad essere tra le pratiche di gestione più premiate nell'ambito di contratti di pagamento volti a tutelare la qualità della risorsa idrica e mitigare i rischio idrogeologico.
Anche se convenzionalmente i PES sono definiti come strumenti di mercato, la maggior parte dei PWS esistenti in Europa dipendono fondamentalmente da enti pubblici che agiscono come intermediari per conto dei cittadini contribuenti. I PWS europei dunque vengono così meglio descritti come sistemi "quasi-PES" attuati da soggetti pubblici, spesso agendo in un quadro istituzionale piuttosto complesso (Vatn, 2010). Di conseguenza, fino ad oggi gli studi si sono concentrati principalmente su esempi provenienti dai Paesi in via di sviluppo e dagli Stati Uniti piuttosto che in Europa (Schomers and Matzdorf, 2013).
Attraverso un approccio snowball e networking europeo, lo studio ha fornito l’inventario più completo di PWS in Europa. Successivamente, attraverso un'analisi comparativa di 76 casi di studio, sono stati caratterizzati i meccanismi istituzionali, economici e di governance associati ai PWS in Europa. Inoltre, per raffinare la comparazione tra casi europei, è stata condotta un’analisi istituzionale più dettagliata di quattro casi di studio in Italia e in Inghilterra.
I risultati mostrano come gli approcci di co-investimento, gli acquisti pubblici e le partnership stanno sostituendo l'idea teorica di transazioni di mercato e commoditization dei servizi ecosistemici.
Il successo dei PWS privati è spesso determinato dalla capacità di integrare diverse fonti di finanziamento, a partire dai sussidi esistenti, investimenti privati e fondi beneficiari dei servizi. I modelli di governance innovativi basati sul partenariato orizzontale (locale-territoriale) e verticale (rispetto alle istituzioni nazionali e internazionali) possono aumentare il loro successo legando gli schemi di pagamento alla valorizzazione dei co-benefits legati alla biodiversità, allo stoccaggio di carbonio e agli obbiettivi di sviluppo socio-economico. Garantire i co-benefits è importante al fine di coinvolgere gli stakeholders e creare interazioni positive, aumentando la scala territoriale d’azione e la capacità tecnica e finanziaria, attraverso il partenariato e il networking. Gli approcci collaborativi forniscono dunque una migliore copertura del territorio, capacità tecnica e finanziaria, che hanno dimostrato essere fattori chiave per il successo PWS.
Per quanto riguarda gli schemi pubblici, quelli che basono il sistema di finanziamento dei PWS sulla semplice allocazione di bilancio annuale, sono spesso messi in difficoltà dall’instabilità politica che influenza la disponibilità delle risorse in base alle decisioni e preferenze politiche. Per evitare l'instabilità e l’incertezza, gli schemi pubblici dovrebbero essere accompagnati da regolamenti che stabiliscono strumenti finanziari, quali tasse di scopo o fondi speciali di accantonamento, che aumentano sistematicamente le risorse finanziarie per alimentare lo schema di pagamento. I PWS che implementano la “tassa di scopo” sulla bolletta idrica e altri che creano fondi di accantonamento appositi dimostrano maggiore longevità, dimensioni e capacità di raggiungere gli obbiettivi prefissati in termini idrogeologic
The impact of debris flow on mitigation structures: a novel depth-averaged and three-dimensional coupled model for the flow dynamic simulation.
Full text linkNumerical analysis of debris-flow interaction with open barriers
Full text linkDebris flows are fast gravity-driven flows consisting of multiple interacting phases. Due to their rapid movement and destructive power, structural mitigation measures have become essential in order to prevent extensive damage to property and life. Among these structures, rigid barriers constitute an efficient system of mitigation, which induces sediment deposition in case of an event. The optimal design of these structures requires the impact force estimation, which has recently become a crucial issue. Because of this, numerous experimental and numerical investigations have been carried out in recent years concerning debris flow and their impact energy on rigid closed barriers. However, there is a lack of information in the framework of rigid open barriers, especially for what concerns the influence of the outlet geometry. In this regard, many studies have examined the jamming of a single-outlet silo, where the mass discharges in the direction of gravity, but the jamming of particles on an inclined slope has not been sufficiently investigated yet. The present numerical study investigates the formation of arching behind an open barrier that partially arrests the flow of particles on an inclined channel. The nature of jamming, and the impact energy on the barrier are examined using DEM simulations for a fixed discharged mass, using different outlet sizes and inclines. The applied model is an improvement of the LBM-DEM code developed by Leonardi et al.. Static friction is implemented with the spring-dashpot linear model and a directional constant torque model is included in order to describe rolling resistance due to elastic deformation and the effect of non-spherical particle shape. The resulting force and momentum at the flow base are analysed in detail together with the kinetic energy and the distribution of particles in the slit. The dynamic impact of the solid component alone is analysed in order to rationalize the design of open barriers. Indeed numerical examples show that a single outlet could jam with a probability that decreases with the slope and the outlet size, but two adjacent outlets do not necessarily jam in the same configuration
Compra Pública Responsabile de Produtos Forestales (Papel y Madera)
No full textGreen public procurement, gestione forestale responsabile, politiche di acquist
Analysis of the load exerted by debris flows on filter barriers: Comparison between numerical results and field measurements
Full text linkThe hazard posed by debris flows onto mountainous settlements often requires structural countermeasures, such as barriers, to be installed. There is a worldwide trend in employing barriers that are partially impervious to the flow, trapping the coarsest sediment, and reducing the erosive power of the flow early on. However, many design choices with respect to effectiveness and structural integrity are not trivial, because there is a poor knowledge of the flow-structure interaction mechanism. In this work, we report results from a monitoring campaign on a barrier installed within an experimental site. At the site, the structural response of the barrier is recorded any time an event occurs. However, the results exhibit features that do not fully reconcile with the load model prescribed by the available guidelines. To gather insight, we propose a numerical study based on the use of the Discrete Elements Method for the flow simulation and the Finite Element Method for the structural response of the barrier. The compatibility between site measurements and numerical output validates the use of the DEM-FEM model. It also highlights certain key details on the load pattern on the barrier that are not yet included in existing guidelines
Numerical analysis of brittle materials fractured by sharp indenters
No full textIndentation can be used to determine the fracture properties of materials. A detailed investigationis here presented on the reliability of finite element simulations of sharp indentations on cracked specimens. Elastic analyses of the stress and deformation fields arising from Vickers, Berkovich and cube-corner indenters generated the stress intensity factor along the edge of penny-shaped or elliptical cracks. Various materials with a range of properties were analysed and the results compared with published experimental data. Additional measurements from tests on soda-lime glass provided further opportunities for experimental validation of numerical predictions. The variation of the stress intensity factor indicated trends for crack growth patterns, which were consistent with experimental observations. Particular attention was given to the evaluation of the geometry-dependent parameter appearing in the relation yielding the fracture toughness of cracked indented materials. The numerical predictions of this parameter were remarkably consistent with experimental data and results from other approximate methods
Efficient coupling between a turbulent flow and mobile bed by means of the level-set method and immersed boundaries
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