Search results for "Hydrograph"
showing 10 items of 47 documents
Genetic architecture of the marbled goby Pomatoschistus marmoratus (Perciformes, Gobiidae) in the Mediterranean Sea
2011
The marbled goby Pomatoschistus marmoratus, a species inhabiting coastal Mediterranean lagoons, has been studied by measuring its mitochondrial DNA variation. This analysis revealed a Mediterranean west vs east split and, subsequently, an eastern differentiation among the Libyan–Tunisian Gulf, the Adriatic Sea and the Aegean Sea. The high cohesion between the samples collected in the vast area of western Mediterranean contrasts with the genetic mosaic of the more sub-structured eastern Mediterranean. This western homogeneity can not yet be fully explained even if a human-mediated migratory flow, due to a maritime traffic, has been posited. The pattern in the eastern basin revealed a genetic…
Relationships between a new slope morphometric index and calanchi erosion in northern Sicily, Italy
2012
The Italian badlands, or “calanchi”, are common landforms in Mediterranean areas including central and southern Italy. Calanchi landforms may be compared to small hydrographic basins. These landforms are characterised by dense, hierarchical and rapidly evolving drainage systems carved into steep clayey slopes and by a sharply alternating pattern of furrows and narrow, generally sharp crests. This work presents a study of morphometric characteristics and a statistical analysis for two sites in northern Sicily (Italy), on outcrops of silty-clay deposits affected by active erosion processes, which give this area a typical calanchi landscape. In particular, factors closely linked to the charact…
Las crecidas en ramblas valencianas mediterráneas
2001
This paper takes into account the characterisation of ephemeral stream hydrology from Mediterranean environments. The heavy floods that these countries suffer are due to firstly, the physical watershed features (steep slopes, scarced vegetation cover and thin soils) and, secondly, to the intense and variable rainfall. Large quantities of precipitation fall in a matter of hours, or even minutes, over very steep catchments, causing catastrophic flash-floods, with very pointed hydrographs and short time lags. Using hydrological daily data from the Rambla de la Viuda basin and five-minute data from both Barranc de Carraixet and Rambla de Poyo basins, we have analysed the rainfall- runoff proces…
Probabilistic Flood Hazard Mapping Using Bivariate Analysis Based on Copulas
2017
This study presents a methodology to extract probabilistic flood hazard maps in an area subject to flood risk, taking into account uncertainties in the definition of design hydrographs. Particularly, the authors present a new method to produce probabilistic inundation and flood hazard maps in which the hydrological input (i.e., synthetic flood design event) to a 2D hydraulic model has been obtained by using a bivariate statistical analysis (copulas) to generate flood peak discharges and volumes. This study also aims to quantify the contribution of boundary conditions’ uncertainty in order to evaluate the effect of this uncertainty source on probabilistic flood hazard mapping. Different comb…
Microplastics in the Center of Mediterranean: Comparison of the Two Calabrian Coasts and Distribution from Coastal Areas to the Open Sea
2021
Plastic is everywhere—increasing evidence suggests that plastic pollution is ubiquitous and persistent in ecosystems worldwide. Microplastic pollution in marine environments is particularly insidious, as small fragmentation can increase interaction with biota and food chain access. Of particular concern is the Mediterranean Sea, which has become a large area of accumulation of plastic debris, including microplastics, whose polymeric composition is still largely unknown. In this study, we analyzed the polymeric composition, particle size distribution, shape, and color of small plastic particles (ranging from 50 to 5000 µm) collected from the sea surface in six stations at the center of the M…
Influence of spatial precipitation sampling on hydrological response at catchment scale
2014
Retrieving precipitation data from raingauge network is a classical and common practice in hydrology and climatology. These data represent the key input in hydrological modeling to reproduce, for example, the characteristics of a flood phenomenon. The accuracy of the model results is strongly dependent on the consistency of the monitoring network in terms of spatial scale, i.e. network density and location of raingauges, and time resolution. In this context, several studies have been carried out to analyze how the rainfall sampling influences the estimation of total runoff volume. The aim of this paper is to use a physically based and distributed-parameter hydrologic model to investigate ho…
Derivation of a Distributed Unit Hydrograph Integrating GIS and Remote Sensing
2007
The paper describes the results of a study based on the integration of remote sensing and geographical information system techniques to evaluate a distributed unit hydrograph model linked to an excess rainfall model for estimating the streamflow response at the outlet of a watershed. Travel time computation, based on the definition of a distributed unit hydrograph, has been performed, implementing a procedure using (1) a cell-to-cell flow path through the landscape determined from a digital elevation model (DEM); and (2) roughness parameters obtained from remote sensing data. This procedure allows the taking into account of the differences, in terms of velocity, between the hillslopes and t…
Coastal erosion in the archaeological area of Selinunte
2010
Coast erosion is a widespread phenomenon and is a considerable issue for the dwellers of coastal areas today. Our study is based on the archaeological area of Selinunte in which we have noticed a process of erosion in progress. In this area we have considered a particular portion of the coast, around 8 km long, since our purpose is the individuation of anthropic elements such as ports, and natural elements, such as rivers. In this area we have set some point of reference using historical and recent cartography in a 1:25.000 scale dating back to 1971, a regional technical paper in a 1: 10.000 scale from 1994, and aerial pictures from 2000 and 2008, all of which we have geo-related starting f…
Continuous Discharge Monitoring Using Non-contact Methods for Velocity Measurements: Uncertainty Analysis
2014
At gauged site, water stage and discharge hydrographs can be related also during unsteady flow conditions, using the one-dimensional diffusive hydraulic model, DORA, and exploiting sporadic surface velocity measurements carried out with a radar sensor, during the rising limb of the flood. Indeed, starting from the measured surface velocity, the application of a simplified entropic velocity distribution model allows obtaining the benchmark discharge for the Manning’s roughness calibration. The aim of this work is twofold. First, to address the uncertainty of the approach. Second, to detect the minimum water level along the rising limb in which the occasional surface velocity measurement shou…
Nouvelles données sur le genre Bragasellus (Crustacea: Isopoda: Asellidae
1996
From now on, the genus Bragasellus Henry & Magniez, 1968 includes 2 oculated and 17 stygobiotic species. As a natural and monophyletic taxonomic unit, we consider it a good genus. Its original area corresponds to the north-west quarter of the Iberian Peninsula. Secondarily, this area has extended eastward, using mainly the alluvial channels of hydrographic systems (Ríos Douro + Ebro and tributaries), finally reaching the underground waters of several Mediterranean rivers. This active expansion is exclusively due to the migration of two stygobiotic sibling species: B. lagari Henry & Magniez, 1973 towards the high basin of the Río Tajo, then downstream to the basins of the Ríos Jucar and Turi…