Search results for " flow"

2017

Abstract. The aim of this study is to present a framework that provides new ways to characterize the spatio-temporal variability of lateral exchanges for water flow and solute transport in a karst conduit network during flood events, treating both the diffusive wave equation and the advection–diffusion equation with the same mathematical approach, assuming uniform lateral flow and solute transport. A solution to the inverse problem for the advection–diffusion equations is then applied to data from two successive gauging stations to simulate flows and solute exchange dynamics after recharge. The study site is the karst conduit network of the Fourbanne aquifer in the French Jura Mountains, wh…

Growth of Arundo donax L. and Cyperus alternifolius L. in a horizontal subsurface flow constructed wetland using pre-treated urban wastewater - a cas…

2013

Constructed wetland systems for wastewater treatment represent an excellent opportunity for the recovery of water resources in those areas subject to prolonged periods of water shortage. This paper presents a study of the efficiency of a pilot horizontal subsurface flow system using pre-treated urban wastewater from a small town in the West of Sicily. The pilot system had a total surface area of 100 m2 with two units. Unit A was planted with Arundo donax L. and unit B with Cyperus alternifolius L. The HLR was 10 cm d-1. The main objectives of research were to evaluate the growth and biomass yield of two macrophytes and determine the removal efficiency of physical-chemical and microbiologica…

Environmental Variables and Planktonic Communities in Two Ponds of El Hondo Wetland (SE Spain)

2001

The annual cycle of physical and chemical variables and plankton dynamics was studied in two shallow ponds (East and West Ponds) of the El Hondo wetland, an ecosystem of international importance. Water conductivity increased up to 31-49 mS cm -1 as water level decreased due to high evaporation and minimal water inputs. Initially considered mesohaline, the waters were reclassified as polyhaline during the hot season. EP was subject to successive desiccation-flooding cycles, and flooding of the dried sediment caused the release of high concentrations of nitrogen and phosphorus compounds, which quickly depleted. The algal species composition was typical of eutrophic ecosystems, and the chlorop…

A multi-gene approach reveals a complex evolutionary history in the Cyanistes species group

2011

Quaternary climatic oscillations have been considered decisive in shaping much of the phylogeographic structure around the Mediterranean Basin. Within this paradigm, peripheral islands are usually considered as the endpoints of the colonization processes. Here, we use nuclear and mitochondrial markers to investigate the phylogeography of the blue tit complex (blue tit Cyanistes caeruleus, Canary blue tit C. teneriffae and azure tit C. cyanus), and assess the role of the Canary Islands for the geographic structuring of genetic variation. The Canary blue tit exhibits strong genetic differentiation within the Canary Islands and, in combination with other related continental species, provides a…

A full‐scale study of Darcy‐Weisbach friction factor for channels vegetated by riparian species

2021

In this article, an open channel flow resistance equation, deduced applying dimensional analysis and incomplete self-similarity condition for the flow velocity distribution, was tested using measurements carried out in a full-scale channel equipped with three types of riparian plants (Salix alba L., Salix caprea L. and Alnus glutinosa L.). In the experimental channel, having banks lined with boulders, the vegetation branches were anchored in a concrete bottom. For each species, the measurements were carried out with plants having different amounts of leaves, different plant density and plant area index. The relationship between the scale factor Γ of the velocity profile and the Froude numbe…

Microstructure, porosity and mineralogy around fractures in Olkiluoto bedrock

2012

3D distributions of minerals and porosities were determined for rock-core samples that included water-conducting fractures. The analysis of these samples was performed using conventional petrography methods, C-14-PMMA porosity analysis and X-ray tomography. It seems that the properties of rock around a water-conducting fracture depend on so many uncorrelated factors that no clear pattern emerged even for rock samples with a given type of fracture. We can conclude, however, that the present combination of methods can be used to infer novel structural information about alteration zones adjacent to fracture surfaces.

El problema del acortamiento de curvas asociado a una densidad

2016

A lo largo de la presente Tesis, se estudia el flujo por la curvatura media asociado a una densidad (FCMpsi) de una hipersuperficie, en una variedad riemanniana con densidad. Los principales resultados se obtienen para el caso particular en el que la dimensión de la variedad ambiente es dos y las subvariedades son curvas. A dicho problema, se le llamará problema del acortamiento de curvas asociado a una densidad (PACpsi). En el capítulo uno, se presentan los conceptos básicos para desarrollar y comprender el trabajo de la Tesis. Se da la definición del problema a abordar, se introducen las herramientas necesarias para su estudio y se calculan las fórmulas de variación de las cantidades geom…

La laguna opaca. Gestión y gobernanza del agua en l’Albufera de València (España)

2019

International audience; The Albufera de Valencia is a complex anthropogenic waterscape, constructed by different social groups over centuries. Today water management in the protected wetland remains opaque, much like the water in the eutrophic lagoon. Four major organiza-tions manage this natural heritage, which remains torn between nature conservation and rice growing, in a jigsaw of overlap-ping jurisdictions and crisscrossed visions. Water management in this socioecological-system is complex and contested, and takes place within a changing scenario due to recent variations in the water quality and quantity budgets. This paper analyses this changing socio-ecological system based on interv…

Flow kinematic characteristics in the scour hole downstream of a grade-control structure

2010

Up-wind difference approximation and singularity formation for a slow erosion model

2020

We consider a model for a granular flow in the slow erosion limit introduced in [31]. We propose an up-wind numerical scheme for this problem and show that the approximate solutions generated by the scheme converge to the unique entropy solution. Numerical examples are also presented showing the reliability of the scheme. We study also the finite time singularity formation for the model with the singularity tracking method, and we characterize the singularities as shocks in the solution.