Snow water equivalent estimation in the Mallero basin using snow gauge data and MODIS images and fieldwork validation     

Davide Bavera  Carlo De Michele 《水文研究》2009,23(14):1961-1972

Snow accumulation and ablation rule the temporal dynamics of water availability in mountain areas and cold regions. In these environments, the evaluation of the snow water amount is a key issue. The spatial distribution of snow water equivalent (SWE) over a mountain basin at the end of the snow accumulation season is estimated using a minimal statistical model (SWE‐SEM). This uses systematic observations such as ground measurements collected at snow gauges and snow‐covered area (SCA) data retrieved by remote sensors, here MODIS. Firstly, SWE‐SEM calculates local SWE estimates at snow gauges, then the spatial distribution of SWE over a certain area using an interpolation method; linear regressions of the first two order moments of SWE with altitude. The interpolation has been made by both confining and unconfining the spatial domain by SCA. SWE‐SEM is applied to the Mallero basin (northern Italy) for calculating the snow water equivalent at the end of the winter season for 6 years (2001–2007). For 2007, SWE‐SEM estimates are validated through fieldwork measurements collected during an ‘ad hoc’ campaign on March 31, 2007. Snow‐surveyed measurements are used to check SCA, snow density and SWE estimates. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Debris flow burial of ancient wall system in the Upper Po River valley     

William C. Mahaney  Pierre Tricart  Rene W. Barendregt  Christopher Carcaillet  Davide Rabufetti  Volli Kalm 《Geology Today》2010,26(6):209-215

The regrouping area, where Hannibal is thought to have reformed his army after forging a path through a massive rockfall in the Cottian Alps, has been reshaped by a blanket of sediment deposited from debris flows following heavy rain in spring, 2008. Analysis of precipitation data for the period mid‐May to mid‐June, 2008, shows that 722 mm of rain fell at 2150 m, falling off to half that amount at 3325 m on the flanks of Mon Viso. Following exhaustive analysis of environmental factors connected with the invasion of Italy at the start of the Second Punic War (218 bc ), identification of the regrouping area for the Carthaginian Army centred on the presence of an ancient stone wall system which possibly dates from Hannibalic times. Lichen cover, lichen diameters, weathering characteristics, degree to which boulders had sunk into the resident soil, and presence of ancient hearths all combined to make this area a choice locale for reconstructive geoarchaeology. Large scale mass wasting off a prominent bedrock bar adjacent to the wall system in the Upper Po River Valley resulted in burial of most of the prominent wall structures which will complicate any exploration geoarchaeology attempts in future.  相似文献   

MTD distribution on a ‘passive’ continental margin: The Espírito Santo Basin (SE Brazil) during the Palaeogene     

Davide Gamboa  Tiago Alves  Joe Cartwright  Pedro Terrinha 《Marine and Petroleum Geology》2010

Mass-wasting on the Brazilian margin during the Mid-Eocene/Oligocene resulted in the accumulation of recurrent Mass Transport Deposits (MTDs) offshore Espírito Santo, SE Brazil. In this paper, we use three-dimensional seismic data to characterize a succession with stacked MTDs (Abrolhos Formation), and to assess the distribution of undeformed stratigraphic packages (i.e. turbidites) with reservoir potential separating the interpreted MTDs. High-amplitude strata in less deformed areas of MTDs reflect their internal heterogeneity, as well as possible regions with a higher sand content. Separating MTDs, turbiditic intervals reach 100 ms Two-Way Travel Time (TWTT), with thicker areas coincident with the flanks of growing diapirs and areas of the basin where mass-wasting is less apparent. Turbiditic strata laterally grade into, or are eroded by MTDs, with transitional strata between MTDs and turbidites being also influenced by the presence of diapirs. MTDs show average thickness values ranging from 58 to 82 ms TWTT and constitute over 50% of Eocene-Oligocene strata along the basin slope. Low average accumulations of 58 ms TWTT in areas of high confinement imposed by diapirs suggest sediment accumulation upslope, and/or bypass into downslope areas. This character was induced by the high sediment input into the basin associated with coastal erosion and growth of the Abrolhos volcanic plateau. Our results suggest that significant amounts of sediment derive from the northwest, and were accumulated in the middle-slope region. Interpretations of (palaeo)-slope profiles led to the establishment of a model of margin progradation by deposition of MTDs, contrasting with the retrogressive erosional margins commonly associated with these settings.  相似文献   

Photochemincal processes involving nitrite in surface water samples     

Claudio Minero  Serge Chiron  Gianpaolo Falletti  Valter Maurino  Ezio Pelizzetti  Roberto Ajassa  Maria Eugenia Carlotti  Davide Vione 《Aquatic Sciences - Research Across Boundaries》2007,69(1):71-85

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The relative importance of ejections and sweeps to momentum transfer in the atmospheric boundary layer     

Gabriel Katul  Davide Poggi  Daniela Cava  John Finnigan 《Boundary-Layer Meteorology》2006,120(3):367-375

Using an incomplete third-order cumulant expansion method (ICEM) and standard second-order closure principles, we show that the imbalance in the stress contribution of sweeps and ejections to momentum transfer (ΔS _o ) can be predicted from measured profiles of the Reynolds stress and the longitudinal velocity standard deviation for different boundary-layer regions. The ICEM approximation is independently verified using flume data, atmospheric surface layer measurements above grass and ice-sheet surfaces, and within the canopy sublayer of maturing Loblolly pine and alpine hardwood forests. The model skill for discriminating whether sweeps or ejections dominate momentum transfer (e.g. the sign of ΔS _o ) agrees well with wind-tunnel measurements in the outer and surface layers, and flume measurements within the canopy sublayer for both sparse and dense vegetation. The broader impact of this work is that the “genesis” of the imbalance in ΔS _o is primarily governed by how boundary conditions impact first and second moments.  相似文献   

Fluidization and injection in the deep-water sandstones of the Eocene Alba Formation (UK North Sea)   总被引：4，自引：0，他引：4  

Davide Duranti  Andrew Hurst 《Sedimentology》2004,51(3):503-529

The Nauchlan Member of the Late Eocene Alba Formation (UK North Sea) consists of a deep‐water channel fill that was extensively modified by post‐depositional sand remobilization and injection. Sandstone textures, facies associations and the geometry of the channel fill were affected. A suite of sand‐rich facies was produced by large‐scale fluidization and injection within the channel fill and above it. These facies, termed here unstratified facies, are characterized by the absence of stratification surfaces and by discordant relationships with bedding in the adjacent succession. They reflect variable degrees of disruption of the primary sedimentary structures caused by escaping pore fluid, the velocity of which is estimated at least in the order of 0·1 ms^?1. Adjacent mudstones were severely disrupted by hydraulic fracturing, and fragments of fractured mudstone were incorporated into the fluidized sand. Average porosity was decreased in the sandstones affected by fluidization. Two main phases of sand injection are inferred to occur at different burial depths. A shallow burial phase (below 100 m) produced thin dykes with ptygmatic folds. The second phase occurred at the boundary between Eocene and Oligocene (≈ 300 m burial depth) and resulted in large‐scale tabular wing‐like dykes that project from the edges of the channel fill. The significant pore‐fluid overpressure, which was required to hydraulically fracture the thick mudstone seal and to fluidize the large volume of sand, was likely to be built up by static liquefaction of the source sand and was possibly enhanced by hydrocarbon gas influx.  相似文献   

Application of newly developed ensemble machine learning models for daily suspended sediment load prediction and related uncertainty analysis     

Ahmad Sharafati  Seyed Babak Haji Seyed Asadollah  Davide Motta 《水文科学杂志》2020,65(12):2022-2042

ABSTRACT

Ensemble machine learning models have been widely used in hydro-systems modeling as robust prediction tools that combine multiple decision trees. In this study, three newly developed ensemble machine learning models, namely gradient boost regression (GBR), AdaBoost regression (ABR) and random forest regression (RFR) are proposed for prediction of suspended sediment load (SSL), and their prediction performance and related uncertainty are assessed. The SSL of the Mississippi River, which is one of the major world rivers and is significantly affected by sedimentation, is predicted based on daily values of river discharge (Q) and suspended sediment concentration (SSC). Based on performance metrics and visualization, the RFR model shows a slight lead in prediction performance. The uncertainty analysis also indicates that the input variable combination has more impact on the obtained predictions than the model structure selection.  相似文献   

Soil C and N response to changes in winter precipitation in a subalpine forest ecosystem,NW Italy   总被引：1，自引：0，他引：1       下载免费PDF全文

Davide Viglietti  Michele Freppaz  Gianluca Filippa  Ermanno Zanini 《水文研究》2014,28(21):5309-5321

Among the potential effects of climate change on subalpine forest ecosystems during the winter season, the shift in snowline towards higher altitudes and the increase in frequency of rain events on the snowpack are of particular interest. Here, we present the results of a 2‐year field experiment conducted in a forest stand (Larix decidua) in NW Italy at 2020 m a.s.l. From 2009 to 2011, we monitored soil physical characteristics (temperature and moisture), and soil and soil solution chemistry, in particular carbon (C) and nitrogen (N) forms and their change in time, as affected by simulated late snowpack accumulation and rain on snow events. Late snowpack accumulation determined a stronger effect on soil thermal and moisture regimes than rain on snow events. Also soil chemistry was significantly affected by late snowfall simulation. Although microbial biomass C and N were not reduced by soil freezing, soil contents of the more labile dissolved organic carbon and inorganic N increased when the soil was affected by mild/hard freezing. Variations in the soil solution were shifted with respect to those observed in soil, with an increase in N‐NO₃^? concentrations occurring during spring and summer. This study highlights the potential N loss in subalpine soils under changing environmental conditions driven by a changing climate. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Catchment-scale storm velocity: quantification,scale dependence and effect on flood response     

Efthymios I. Nikolopoulos  Marco Borga  Davide Zoccatelli  Emmanouil N. Anagnostou 《水文科学杂志》2014,59(7):1363-1376

Abstract

The concept of “catchment-scale storm velocity” quantifies the rate of storm motion up and down the basin accounting for the interaction between the rainfall space–time variability and the structure of the drainage network. It provides an assessment of the impact of storm motion on flood shape. We evaluate the catchment-scale storm velocity for the 29 August 2003 extreme storm that occurred on the 700 km²-wide Fella River basin in the eastern Italian Alps. The storm was characterized by the high rate of motion of convective cells across the basin. Analysis is carried out for a set of basins that range in area from 8 to 623 km² to: (a) determine velocity magnitudes for different sub-basins; (b) examine the relationship of velocity with basin scale and (c) assess the impact of storm motion on simulated flood response. Two spatially distributed hydrological models of varying degree of complexity in the representation of the runoff generation processes are used to evaluate the effects of the storm velocity on flood modelling and investigate model dependencies of the results. It is shown that catchment-scale storm velocity has a non-linear dependence on basin scale and generally exhibits rather moderate values, in spite of the strong kinematic characteristics of individual storm elements. Consistently with these observations and for both models, hydrological simulations show that storm motion has an almost negligible effect on the flood response modelling.

Editor Z.W. Kundzewicz; Guest editor R.J. Moore

Citation Nikolopoulos, E.I., Borga, M., Zoccatelli, D., and Anagnostou, E.N., 2014. Catchment-scale storm velocity: quantification, scale dependence and effect on flood response. Hydrological Sciences Journal, 59 (7), 1363–1376. http://dx.doi.org/10.1080/02626667.2014.923889  相似文献   

Soil water dynamics at a midlatitude test site: Field measurements and box modeling approaches     

Mara Baudena  Ivan Bevilacqua  Davide Canone  Stefano Ferraris  Maurizio Previati  Antonello Provenzale 《Journal of Hydrology》2012

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