Search results for "forest"
showing 10 items of 3780 documents
Testing flow resistance equation for rill flow
2018
At first, in this paper a flow resistance equation for rill flow, deduced applying dimensional analysis and self-similarity theory, is presented. The incomplete self-similarity hypothesis is used for establishing the flow velocity distribution whose integration gives the theoretical expression of the Darcy-Weisbach friction factor. Then the deduced theoretical resistance equation, which is calibrated by some measurements of flow velocity, water depth, cross section area, wetted perimeter and bed slope carried out in 106 reaches of some rills modelled on an experimental plot, is tested using the literature data by Abrahams et al. (1996), Strohmeier et al. (2014) and Peng et al. (2015) for ri…
Effects of Boulder Arrangement on Flow Resistance Due to Macro-Scale Bed Roughness
2023
Flow resistance in gravel-bed channels is not only affected by the shape and size of the roughness elements, but also by their arrangement on the channel bed surface (position to flow streamlines, spacing between elements, and their protrusion from the channel bed). Many investigations proved that open channel flow resistance can be obtained by integrating the power velocity profile. For a macro-scale roughness condition, this study aims to investigate the effect of different boulder arrangements on flow resistance. First, for each arrangement, the equation relating Γ function of the power velocity profile, the Froude number, and the channel slope was calibrated using available measur…
Experimental investigation of flow characteristics in vegetated channels
2006
Beneficiation, desilication and selective precipitation techniques for phosphorus refining from biomass derived fly ash
2018
The supply of affordable phosphorus (P), a biocritical element, is at great risk due to the utilization of limited natural phosphate minerals at an unprecedented scale. The need of phosphorus recovery to sustain the anthropogenic P-cycle was recog- nized and fly ash, a waste product from the combustion of renewable biofuels, was selected as the secondary resource. Increasing supply of fly ash in the future due to growing use of forest biofuels in energy production also contributes to its suitability for P-recovery. Fly ash comprises of silicates, oxides, carbonates, phosphates and hydroxides of the elements that potentially represent the entire periodic table. This only augments the complexity…
Indice de réflexion latérale du saumon Atlantique (Salmo salar), de la truite de mer (Salmo trutta), du corégone (Coregonus lavaretus) et du brochet …
2000
L'indice de reflexion acoustique laterale (TS) de 19 saumons Atlantique (Salmo salar), 16 truites de mer (Salmo trutta), 10 coregones (Coregonus lavaretus) et 7 brochets (Esox lucius) a ete mesure en utilisant un sondeur de 200 kHz, afin d'etudier la relation entre l'indice TS et la taille, le poids et la surface du poisson. Les effets de l'angle d'incidence sur l'indice TS ont aussi ete etudies. Des modeles lineaires entre TS et le logarithme de l'indice de taille du poisson ont ete ajustes et ont montre que la meilleure prevision provient de l'indice de longueur. Classiquement, l'erreur standard de l'estimation etait de 1,2 a 2,9 dB. Les resultats des mesures de TS sur des poissons de lon…
Biomass Assessment of Agricultural Crops Using Multi-temporal Dual-Polarimetric TerraSAR-X Data
2019
The biomass of three agricultural crops, winter wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), and canola (Brassica napus L.), was studied using multi-temporal dual-polarimetric TerraSAR-X data. The radar backscattering coefficient sigma nought of the two polarization channels HH and VV was extracted from the satellite images. Subsequently, combinations of HH and VV polarizations were calculated (e.g. HH/VV, HH + VV, HH × VV) to establish relationships between SAR data and the fresh and dry biomass of each crop type using multiple stepwise regression. Additionally, the semi-empirical water cloud model (WCM) was used to account for the effect of crop biomass on radar backscatter …
Caracterización Eco-geográfica de melloco (Ullucus tuberosus C.) En la Región Alto Andina del Ecuador
2018
Ecogeographic characterization of Melloco (Ullucus tuberosus C.) in the high Andean region of Ecuador
 Resumen
 El estudio se llevó a cabo en la región alto Andina del Ecuador, utilizando la colección nacional de Melloco (Ullucus tuberosus C.), perteneciente al Banco Nacional de Germoplasma del INIAP. El objetivo fue evaluar las características de los sitios de colecta, identificar rangos climáticos y ecosistemas favorables o marginales para el cultivo. Para la caracterización se utilizó información geo-referencial de puntos de colecta y 13 variables climáticas, geofísicas y edáficas. Se generó un Mapa de Caracterización Eco-geográfica del Terreno Específico (mapa ELC) aplicando l…
Evaluating the Effectiveness of Forest Crop to Mitigate Erosion Using a Sediment Delivery Distributed Model
1998
In this paper sediment yield data, measured from 1978 to 1997 in a small experimental Calabrian basin reafforested with Eucalyptus trees (Eucalyptus occidentalis Engl.), and RUSLE (Revised Universal Soil Loss Equation) coupled with a sediment delivery distributed model are used to evaluate the antierosive effects of this forest cover. At first, the soil loss measureinents carried out in two experimental plots, located in the basin, are used to evaluate the crop and management factor C of RUSLE far Eucalyptus coppice. The reliability of the selected C factor value is verified by comparing, at an event scale, the measured and the calculated sediment yield values at the basin outlet. Then, a M…
The Italian endemic forest plants: an annotated inventory and synthesis of knowledge
2023
Background and aims – Forests are among the most threatened ecosystems worldwide, and endemic plants are often a vulnerable component of the flora of a given territory. So far, however, understory forest endemics of southern Europe have received little attention and are poorly known for several aspects. Material and methods – We developed the first list of native vascular plants that are restricted to Italian forests. Available information on taxonomy, regional distribution, ecology, biology, functional traits, and conservation status was collected for each taxon, allowing to identify major knowledge gaps and calculate baseline statistics. Key results – The list includes 134 taxa, most of w…