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David D. Bosch Alisa W. Coffin Joseph Sheridan Oliva Pisani Dinku M. Endale Tim C. Strickland 《水文研究》2021,35(8):e14334
The US Department of Agriculture-Agricultural Research Service Southeast Watershed Research Laboratory (SEWRL) initiated a hydrologic research program on the Little River Experimental Watershed (LREW) in 1967. Long-term (52 years) streamflow data are available for nine sites, including rainfall-runoff relationships and hydrograph characteristics regularly used in research on interactive effects of climate, vegetation, soils, and land-use in low-gradient streams of the US EPA Level III Southeastern Plains ecoregion. A summary of prior research on the LREW illustrates the impact of the watershed on building a regional understanding of hydrology and water quality. Climatic and streamflow data were used to make comparisons of scale across the nine nested LREW watersheds (LRB, LRF, LRI, LRJ, LRK, LRO, LRN, LRM, and LRO3) and two regional watersheds (Alapaha and Little River at Adel). Annual rainfall for the largest LREW, LRB, was 1200 mm while average annual streamflow was 320 mm. Annual rainfall, streamflow, and the ratio between annual streamflow and rainfall (Sratio) were similar (α = 0.05) across LREWs LRB, LRF, LRI, LRJ, LRK, and LRO. While annual rainfall within the 275 ha LRO3 was found to be similar to LRO and LRM (α = 0.05), annual streamflow and Sratio were significantly different (α = 0.05). Comparisons of annual rainfall, streamflow, and Sratio between LRB and the regional watersheds indicated no differences (α = 0.05). Based upon this analysis, most regional watersheds shared similar hydrologic characteristics. LRO3 was an exception, where increases in row crops and decreases in forest coverage resulted in increased streamflow. LREW data have been instrumental in building considerable scientific understanding of flow and transport processes for these stream systems. Continued operation of the LREW hydrologic network will support hydrologic research as well as environmental quality and riparian research programs that address emerging and high priority natural resource and environmental issues. 相似文献
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J. Espinha Marques J. Samper B. Pisani D. Alvares J. M. Carvalho H. I. Chaminé J. M. Marques G. T. Vieira C. Mora F. Sodré Borges 《Environmental Earth Sciences》2011,62(6):1219-1234
High-mountain basins provide a source of valuable water resources. This paper presents hydrological models for the evaluation
of water resources in the high-mountain Zêzere river basin in Serra da Estrela, Central Portugal. Models are solved with VISUAL BALAN v2.0, a code which performs daily water balances in the root zone,
the unsaturated zone and the aquifer and requires a small number of parameters. A lumped hydrological model fails to fit measured
stream flows. Its limitations are overcome by considering the dependence of the temperature and precipitation data with elevation
and the spatial variability in hydrogeomorphological variables with nine sub-basins of uniform parameters. Model parameters
are calibrated by fitting stream flow measurements in the Zêzere river. Computed stream flows are highly sensitive to soil
thickness, whereas computed groundwater recharge is most sensitive to the interflow and percolation recession coefficients.
Interflow is the main component of total runoff, ranging from 41 to 55% of annual precipitation. High interflows are favored
by the steep relief of the basin, by the presence of a high permeability soil overlying the fractured low permeability granitic
bedrock and by the extensive subhorizontal fracturing at shallow depths. Mean annual groundwater recharge ranges from 11 to
15% of annual precipitation. It has a significant uncertainty due to uncertainties in soil parameters. This methodology proves
to be useful to handle the research difficulties regarding a complex mountain basin in a context of data scarcity. 相似文献
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-quartz and stishovite have been studied using a periodic ab-initio Hartree-Fock method in order to characterize the chemical nature of the Si-O bond and the way in which it changes with the coordination number of Si. Structural properties, including unit cell volume and c/a ratio have been optimized in order to evaluate the reliability of the method and the effect of the basis set. Density of states and electron charge density maps have been taken into account to investigate the electronic properties of the two systems and the rôle played by different orbitals. We also present comparisons with experimental X-ray emission data. The importance of d orbitals is stressed by our calculations, and a possible interpretation of the Si-O bond proposed. Quartz is found to be more covalent than stishovite. 相似文献
5.
Simona Scollo Antonella Boselli Mauro Coltelli Giuseppe Leto Gianluca Pisani Nicola Spinelli Xuan Wang 《Bulletin of Volcanology》2012,74(10):2383-2395
In this paper, we use data obtained from LiDAR measurements during an ash emission event on 15 November 2010 at Mt. Etna, in Italy, in order to evaluate the spatial distribution of volcanic ash in the atmosphere. A scanning LiDAR system, located at 7?km distance from the summit craters, was directed toward the volcanic vents and moved in azimuth and elevation to analyse different volcanic plume sections. During the measurements, ash emission from the North East Crater and high degassing from the Bocca Nuova Crater were clearly visible. From our analysis we were able to: (1) evaluate the region affected by the volcanic plume presence; (2) distinguish volcanic plumes containing spherical aerosols from those having non-spherical ones; and (3) estimate the frequency of volcanic ash emissions. Moreover, the spatial distribution of ash mass concentration was evaluated with an uncertainty of about 50?%. We found that, even during ash emission episodes characterised by low intensity like the 15 November 2010 event, the region in proximity of the summit craters should be avoided by air traffic operations, the ash concentration being greater than 4?×?10?3?g/m3. The use of a scanning permanent LiDAR station may usefully monitor the volcanic activity and help to drastically reduce the risks to aviation operations during the frequent Etna eruptions. 相似文献
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S. Bardelli A. Pisani M. Ramella E. Zucca & G. Zamorani 《Monthly notices of the Royal Astronomical Society》1998,300(2):589-598
The 'algorithm driven by the density estimate for the identification of clusters' ( DEDICA ) is applied to the A3558 cluster complex in order to find substructures. This complex, located at the centre of the Shapley Concentration supercluster, is a chain formed by the ACO clusters A3556, A3558 and A3562 and the two poor clusters SC 1327-312 and SC 1329-313. We find a large number of clumps, indicating that strong dynamical processes are active. In particular, it is necessary to use a fully three-dimensional sample (i.e. using the galaxy velocity as third coordinate) in order also to recover the clumps superimposed along the line of sight. Even though a large number of detected substructures was already found in a previous analysis, this method is more efficient and faster when compared with a wide battery of tests, and permits the direct estimate of the detection significance. Almost all subclusters previously detected by the wavelet analyses found in the literature are recognized by DEDICA . On the basis of the substructure analysis, we also briefly discuss the origin of the A3558 complex by comparing two hypotheses: (i) the structure is a cluster–cluster collision seen just after the first core–core encounter; or (ii) this complex is the result of a series of incoherent group–group and cluster–group mergings, focused in that region by the presence of the surrounding supercluster. We studied the fraction of blue galaxies in the detected substructures and found that the bluest groups reside between A3562 and A3558, i.e. in the expected position for the scenario of cluster–cluster collision. 相似文献
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Naves Acacia Samper Javier Pisani Bruno Mon Alba Dafonte Jorge Montenegro Luis García-Tomillo Aitor 《Hydrogeology Journal》2021,29(8):2655-2669
Groundwater availability, management and protection are great challenges for the sustainability of groundwater resources in the scattered rural areas of the Atlantic regions of Europe where groundwater is the only option for water supply. This report presents a hydrogeological study of the coastal granitic area of Oia in northwestern Spain, which has unique geomorphological and hydrogeological features with steep slopes favoring the erosion of the weathered granite. The hydrogeological conceptual model of the study area includes: (1) the regolith layer, which is present only in the flat summit of the mountains; (2) the slope debris and the colluvial deposits, which are present in the intermediate and lowest parts of the hillside; (3) the marine terrace; and (4) the underlying fractured granite. Groundwater recharge from rainfall infiltration varies spatially due to variations in terrain slope, geology and land use. The mean annual recharge estimated with a hydrological water balance model ranges from 75 mm in the steepest zone to 135 mm in the lowest flat areas. Groundwater flows mostly through the regolith and the detrital formations, which have the largest hydraulic conductivities. Groundwater discharges in seepage areas, springs, along the main creeks and into the sea. The conceptual hydrogeological model has been implemented in a groundwater flow model, which later has been used to select the best pumping scenario. Model results show that the future water needs for domestic and tourist water supply can be safely provided with eight pumping wells with a maximum pumping rate of 700 m3/day.
相似文献10.
Antonella Boselli Mario Armenante Loredana D’Avino Massimo D’Isidoro Gianluca Pisani Nicola Spinelli Xuan Wang 《Boundary-Layer Meteorology》2009,132(1):151-165
The evolution of the planetary boundary layer and the influence of local circulation phenomena over Naples (southern Italy,
40.838° N, 14.183° E, 118 m above sea level) have been studied by systematic lidar measurements of aerosol optical properties
and vertical distributions carried out from May 2000 to August 2003, in the course of the EARLINET project. In particular,
our data show the development of aerosol layers typically located in the range between 1,000 and 2,300 m, with variable thickness.
The optical properties of the observed layers have been determined. In order to analyse the evolution of the planetary boundary
layer, detailed observations of complete diurnal cycles have also been performed. The analysis of lidar measurements of vertical
profiles of wind speed and wind direction and air mass back-trajectories allowed us to characterize the sea-breeze circulation
influence on both the planetary boundary-layer evolution and the observed aerosol vertical distribution. 相似文献