Search results for "feature"
showing 10 items of 4091 documents
Water quality modelling for ephemeral rivers: Model development and parameter assessment
2010
Summary River water quality models can be valuable tools for the assessment and management of receiving water body quality. However, such water quality models require accurate model calibration in order to specify model parameters. Reliable model calibration requires an extensive array of water quality data that are generally rare and resource-intensive, both economically and in terms of human resources, to collect. In the case of small rivers, such data are scarce due to the fact that these rivers are generally considered too insignificant, from a practical and economic viewpoint, to justify the investment of such considerable time and resources. As a consequence, the literature contains v…
Uncertainty assessment of an integrated urban drainage model
2009
Over the last few years, the use of mathematical models has gained importance in urban drainage system management; indeed, such models enable the combined analysis of different components that constitute a drainage system; the sewer system, wastewater treatment plant and the receiving water body. The effectiveness of an integrated approach has been widely demonstrated in the past and is presented in the EU Water Framework Directive, which also introduces a new point of view regarding the water quality management of the whole system, requiring a global analysis at the river basin scale for pollutant sources. However, integrated urban drainage models introduce several uncertain factors that a…
Fuel load and flight ranges of blackcaps Sylvia atricapilla in northern Iberia during autumn and spring migrations
2009
Abstract Fuel accumulation, mainly as fatty acids, is one of the main characteristics of migratory birds. Studying to what extent each population or species manages fuel load and how it varies along routes of migration or between seasons (autumn and spring migrations) is crucial to our understanding of bird migration strategies. Our aim here was to analyse whether migratory blackcaps Sylvia atricapilla passing through northern Iberia differ in their mean fuel loads, rate of fuel accumulation and ‘potential’ flight ranges between migration seasons. Blackcaps were mist netted for 4 h-periods beginning at dawn from 16 September to 15 November 2003 - 2005, and from 1 March to 30 April 2004 - 20…
Geochemical and hydrogeological characterization of thermal springs in Western Sicily, Italy
1998
Abstract Thermal and cold waters from Castellammare–Alcamo (Western Sicily-Italy) were collected between May 1994 and May 1995 and studied for their chemical and isotopic composition. During the same period, mean monthly samples of meteoric water were also collected and measured for their isotopic composition. The main purpose of this study was the characterization of the acquifers and, if possible, of their recharge areas. According to the results obtained, the acquifers were divided into three main groups: (a) selenitic waters, (b) cold carbonatic waters, and (c) deep thermal waters resulting from the mixing of the other two types. Besides a mixing process between carbonatic and selenitic…
Characterisation of submarine groundwater discharge offshore south-eastern Sicily
2005
A complex approach in characterisation of submarine groundwater discharge (SGD) off south-eastern Sicily comprising applications of radioactive and non-radioactive tracers, direct seepage measurements, geophysical surveys and a numerical modelling is presented. SGD fluxes in the Donnalucata boat basin were estimated by direct seepage measurements to be from 4 to 12Ls(-1), which are comparable with the total SGD flux in the basin of 17Ls(-1) obtained from radon measurements. The integrated SGD flux over the Donnalucata coast estimated on the basis of Ra isotopes was around 60m(3)s(-1) per km of the coast. Spatial variations of SGD were observed in the Donnalucata boat basin, the average (222…
Geochemical monitoring of groundwaters (1998-2001) at Vesuvius volcano (Italy)
2004
This work presents the results of hydrogeochemical studies carried out at Vesuvius during the period May 1998-December 2001, mostly focusing on compositional time variations observed during this time. Based on their chemistry, groundwater samples are distinguished into two groups, 1 and 2, representative of water circulation in the southern and northern sectors of the volcano, respectively. Waters from group 1 are typically more acidic, warmer, and more saline than those of group 2. They also have higher CO2 and CH4 contents, attributed to enhanced input of deep-rising volatiles and prolonged water-rock interactions. Time-series highlight the fairly constant chemical composition of the enti…
The impact of road and railway embankments on runoff and soil erosion in eastern Spain
2015
Abstract. Road and railway infrastructure increased in the Mediterranean region during the last three decades. This included the building of embankments, which are assumed to be a~large source of sediments and runoff. However, little is known about soil erosion rates, the factors that control them, and the processes that contribute to detachment, transport and deposition of sediments from road and railway embankments. The objective of this study was therefore to assess the impacts of road and railway embankments as a source of sediment and water, and compare them to other land use types (citrus plantations and shrublands) representative of the Cànyoles watershed to evaluate the importance o…
Geochemical insight into differences in the physical structures and dynamics of two adjacent maar lakes at Mt. Vulture volcano (southern Italy)
2013
[1] We report on the first geochemical investigation of the Monticchio maar lakes (Mt. Vulture volcano, southern Italy) covering an annual cycle that aimed at understanding the characteristic features of the physical structures and dynamics of the two lakes. We provide the first detailed description of the lakes based on high-resolution conductivity-temperature-depth (CTD) profiles, chemical and isotopic (H and O) compositions of the water, and the amounts of dissolved gases (e.g., He, Ar, CH4, and CO2). The combined data set reveals that the two lakes, which are separated by less than 200 m, exhibit different dynamics: one is a meromictic lake, where the waters are rich in biogenic and man…
Volcanic steam output directly measured in fumaroles: the observed variations at Vulcano Island, Italy, between 1983 and 1987
1992
The mass of steam emitted by the fumaroles of the crater of Vulcano (Aeolian Islands, Italy) was evaluated by using a direct measuring method. Measurements were effected with this method between 1983 and 1987 in nine field campaigns, the results of which are given in this paper. The steam flux measurements were performed by an instrument expressly designed for steam condensation. The estimates of the thermal energy transported daily by the steam gave values of up to 10E12 J. The sharp variations in the total mass outputs recorded in 1984 and 1985 are here interpreted as being a consequence of the probable accumulation of fluid pressure at depth, during the evolution of volcanic activity. Th…
The influence of aspect and vegetation on seasonal changes in erosion under rainfall simulation on a clay soil in Spain
1998
The seasonal and spatial variability of soil erosion under contrasting slope aspects in southeastern Spain was studied by performing and interpreting 84 rainfall simulation experiments conducted at an intensity of 55 mm h−1 during 1 h. The vegetated soils on the north-facing slope and the upper afforested parts had negligible sediment yield, runoff and erosion, while the bare soils on the south-facing slope had very high runoff rates. Runoff sediment concentration decreased over time during simulated rainfall events on the vegetated areas while it increased on the bare ones. Solute release decreased over time on both surface types. Seasonally, runoff sediment concentration was highest in a…