Search results for "DRAINAGE"
showing 10 items of 381 documents
Flow hydraulic characteristics determining the occurrence of either smooth or abrupt sewer pressurization
2014
Laboratory experiments showed that pipe pressurization consequent on a drastic reduction in the downstream discharge can occur either by a gradual rising of the free-surface (“smooth” pressurization) or by propagation of a front filling the whole cross-section (“abrupt” pressurization). This study examines the free-surface flow characteristics that determine smooth or abrupt pressurization pattern through a theoretical approach using dimensionless variables. A critical flow rate value, which separates the pressurization patterns, exists for any given pipe diameter. For flow rates higher than this specific value, only abrupt pressurization occurs. For lower flow rates, either smooth or abrup…
Comment on ?Measuring the flow resistance of submerged grass? by C. A. M. E. Wilson and M. S. Horritt,Hydrological Processes 16: 2589-2598
2005
In this short note, the experimental data of Wilson and Horritt (2002. Hydrological Processes16: 2589–2598), jointly with the measurements by Kouwen et al. (1969. Journal of Irrigation and Drainage Division, ASCE95: 329–342) and by Raffaelli et al. (2002 In Proceedings XXVIII Convegno di Idraulica e Costruzioni Idrauliche, Cosenza, Italy; 223–230), are firstly used to test Kouwen's approach. All experimental data are then used to calibrate a flow resistance equation that was theoretically deduced by dimensional analysis and self-similarity theory. Copyright © 2005 John Wiley & Sons, Ltd.
Flood frequency analysis for an urban watershed: comparison between several statistical methodologies simulating synthetic rainfall events
2016
To obtain the flooding frequency distribution for an urban watershed, different methods based on simulations of synthetic rainfall events were compared with an empirical analysis of the flooding data and with the results of long-term simulations. A copula-based multivariate statistical analysis of the main hydrological variables was proposed to generate synthetic hyetographs. Two different approaches were adopted to assess a temporal pattern to the synthetic rainfall: one analyses all available historical rainfall patterns, and another adopts the cluster analysis in three different variants to reduce the computational effort of the analysis. To test the methodology reliability, the analysis…
Macrobotanical evidence (wood charcoal and seeds) from the Middle Palaeolithic site of El Salt, Eastern Iberia: Palaeoenvironmental data and plant re…
2018
Despite the current growing number of studies that focus on macrobotanical remains from Middle Palaeolithiccontexts, plant use among hunter-gatherer societies remains unknown in many regions of Europe. Large-scaleflotation of archaeological sediments has made it possible to recover a large amount of plant remains (fruits,seeds and wood) from units VIII, IX, Xa and Xb at El Salt, Eastern Iberia (49.2–52.3 ka BP). The combination ofanthracological and carpological analyses has provided a more accurate picture of the Middle Palaeolithiclandscape in the Serpis valley, as well as significant information about other possible uses of plants, not only asfuel, but for woodworking or food, for instan…
Gadoxetate disodium-enhanced magnetic resonance cholangiography for the noninvasive detection of an active bile duct leak after laparoscopic cholecys…
2010
Abstract We report a case of an endoscopically confirmed biliary leak of the common hepatic duct after laparoscopic cholecystectomy that was prospectively diagnosed on gadoxetate disodium-enhanced magnetic resonance cholangiography. Whereas dynamic contrast-enhanced magnetic resonance images during the early vascular phases helped to rule out the causes of possible complications such as seroma, hematoma, or abdominal abscess, delayed hepatobiliary phase imaging was crucial for unequivocal diagnosis and location of the biliary leak. The diagnosis prompted therapeutic endoscopic retrograde cholangiography whereby a polytetrafluoroethylene-covered nitinol stent graft was successfully placed to…
Genetic diversity of two perch Perca fluviatilis populations of the Latgale region
2015
Molecular markers based on retrotransposons possibility of integration into genomes of many organisms are commonly used for genetic analysis of different species. The aim of this study was to test possibility of use those markers in perch and detect genetic diversity of populations of two lakes of the Latgale region of Latvia: Cirišs and Sventes. The distance between the lakes is nearly 60 km, they belong to the same Daugava river basin but are different from ecological point of view. Forty two blood samples of <em>Perca fluviatilis </em>were collected altogether. Extracted DNA was analyzed using inter-PBS amplification technique with specifically selected retrotransposon-based …
Spatial prediction of soil erosion susceptibility using a fuzzy analytical network process: Application of the fuzzy decision making trial and evalua…
2018
Soil erosion is a worldwide threat that results in soil degradation, agriculture abandonment, and crop yield reduction. There is a need to find methods to survey soil erosion rates in order to improve and develop sustainable land planning. The present study utilizes new approaches based on the fuzzy set both in designing the problem (through the fuzzy decision making trial and evaluation laboratory) and in prioritizing the effective factors to mitigate soil erosion (using a fuzzy analytical network process, FANP). This study is first to apply these methods to soil erosion. A set of geo‐environmental factors influencing soil erosion was characterized to evaluate the potential risk of soil er…
Assessing physical surrogates for biodiversity: Do tributary and stream type classifications reflect macroinvertebrate assemblage diversity in runnin…
2006
Landscape classifications are increasingly being used in conservation planning and biodiversity management, although there is a dearth of studies actually showing concordant patterns between such classifications and biodiversity. We studied the utility of tributary and stream type classifications in accounting for the variability of invertebrate biodiversity in a boreal drainage system. We found that only weak, although significant, differences existed between the studied three tributaries and four stream types in macroinvertebrate assemblage structure, species distributions, and taxonomic richness. Further, the classification strengths, calculated as mean within-group-similarity minus mean…
Pesticide monitoring in the basin of Llobregat River (Catalonia, Spain) and comparison with historical data.
2014
Through an extensive sampling in the Llobregat River basin, the presence of 50 currently used pesticides in water, sediment, and biota was assessed. Pesticides were detected primarily in water (up to 56% of the analytes), whereas their presence in sediments was more intermittent, and in biota was scarce. Those at high concentrations in water were the benzimidazoles (carbendazim in 22% of the samples up to 697ngL-1), the organophosphorus (malathion in 54% of the samples up to 320ngL-1), and the ureas (diuron in 54% of the samples up to 159ngL-1). However, this pattern differed in sediments and biota, which were contaminated primarily with organophosphorus (higher Kow) (chlorpyrifos 93% of se…
Boron and lithium behaviour in river waters under semiarid climatic conditions
2022
Boron (B) and Lithium (Li) concentrations were studied in the Platani river, one of the most important catchments of South-Central Sicily which is under semiarid climatic conditions for roughly eight months to a year. In this area, evaporites result in potential B and Li sources for surface waters. Results from river waters have measured ionic strength values between 0.1 and 4.54 M. B and Li distributions in these waters were studied in colloidal (CF, extracted by ultrafiltration from the 0.45 μm filtrate) and total dissolved (TDF) fractions and in fractions extracted from corresponding riverbed sediments, according to changes of the B/Li ratio. In river waters, CF and TDF showed very simil…