Search results for "stream"
showing 10 items of 682 documents
Role of hydrological and hydromorphological factors in ecological quality of medium-sized lowland streams
2010
The development of biological communities is an important research issue regarding biological quality elements. However, it is still uncertain how different organism groups and their metrics are affected by different environmental factors. A study of high-quality sites of medium-sized lowland streams typical for Latvia (ecoregion Baltic province) was carried out with an emphasis on hydrological and hydromorphological characteristics. The investigations were carried out within the STAR project using the project designated standard methods. We found that the level of saprobity according to benthic macroinvertebrates was mainly linked with substrate type and stream depth. The trophic diatom in…
Impacts of Climate on the Flux of Dissolved Organic Carbon from Catchments
2010
Recent increases in dissolved organic carbon (DOC) concentrations in surface waters across both Europe and North America have focused attention on the factors controlling the export of DOC compounds from catchments. Waters containing high concentrations of DOC generally have a characteristic brown colour and are associated with the presence of highly organic soils. Catchments dominated by these soils typically export between 10 and 300 kg DOC ha−1 year−1 (Billett et al., 2004; Laudon et al., 2004; Jonsson et al., 2006). A portion of this DOC is mineralised in streams and lakes to CO2, while the remainder is transported to the sea (Jonsson et al., 2006). Organic matter accumulates in soils w…
EHSM: a conceptual ecohydrological model for daily streamflow simulation
2013
A parsimonious conceptual lumped model is here presented with the aim of simulating daily streamflow in semi-arid areas. The model, processing daily rainfall and reference evapotranspiration at basin scale, reproduces surface and subsurface runoff, soil moisture dynamics, and actual evapotranspiration fluxes. The key elements of this numerical model are the soil bucket, where rainfall, evapotranspiration, and leakage drive soil moisture dynamics, and two linear reservoirs working in parallel with different characteristic response times. The surface reservoir, able to simulate the fast response of the basin, is fed by rain falling on impervious area and by runoff generated with excess of sat…
A GIS-Based Model for the analysis of an urban flash flood and its hydro-geomorphic response. The Valencia event of 1957
2016
Summary Flash floods are recurrent events around the Mediterranean region. Extreme episodes activate hydro-geomorphic high-intensity processes with low frequency. In urban environments, the complexity becomes higher due to the existence of very quick-response runoff. However, immediate recovery works remove the urban marks. After a short time both the significance and magnitude of the hydro-geomorphic event become completely unrecognizable. Nevertheless, these episodes generate extensive documentation which is testimony of the processes in almost real time. It is necessary to exploit this source typology in order to draw flood sketches when events far in time may lack a sufficiently rich da…
ASSESSMENT OF RIVER FLOW WITH SIGNIFICANT LATERAL INFLOW THROUGH REVERSE ROUTING MODELING
2017
The discharge hydrograph estimation in rivers based on reverse routing modeling and using only water level data at two gauged sections is here extended to the most general case of significant lateral flow contribution, without needing to deploy rainfall-runoff procedures. The proposed methodology solves the Saint-Venant equations in diffusive form also involving the lateral contribution using an ‘head driven’ modeling approach where lateral inflow is assumed to be function of the water level at the tributary junction. The procedure allows to assess the discharge hydrograph at ends of a selected river reach with significant lateral inflow, starting from the stage recorded there and without n…
Regional flow duration curves for ungauged sites in Sicily
2011
Abstract. Flow duration curves are simple and powerful tools to deal with many hydrological and environmental problems related to water quality assessment, water-use assessment and water allocation. Unfortunately the scarcity of streamflow data enables the use of these instruments only for gauged basins. A regional model is developed here for estimating flow duration curves at ungauged basins in Sicily, Italy. Due to the complex ephemeral behaviour of the examined region, this study distinguishes dry periods, when flows are zero, from wet periods using a three parameters power law to describe the frequency distribution of flows. A large dataset of streamflows has been analysed and the param…
Comparing long term sediment records to current biological quality element data – Implications for bioassessment and management of a eutrophic lake
2012
Defining reference conditions for lakes situated in areas of human settlement and agriculture is rarely straightforward, and is especially difficult within easily eroding and nutrient rich watersheds. We used diatoms, cyanobaterial akinetes, remains of green algae and chironomid head capsules from sediment samples of Lake Kirmanjarvi, Finland, to assess its deviation from the initial ecological status. These site-specific records of change were compared to current type-specific ecological status assessment. All paleolimnological data indicated deviation from natural conditions and mirrored the current, monitoring-based assessment of “moderate” ecological lake status. However, the sediment d…
Universidad Politécnica Radiotelevisión. Creación y primera etapa (2000-2008)
2012
En el artículo se trata la historia de los canales UPVRadio y Universidad Politécnica Televisión desde el año 2000 a 2008, incluyendo el proceso de estudio, diseño y puesta en marcha de ambos y una descripción de los objetivos, el modelo de gestión, la plantilla, los canales de emisión, la programación, la audiencia y las fuentes de financiación alternativa en el régimen permanente. Se comenta también la infraestructura de soporte de ambos canales, con apartados para las dependencias de la cadena, el equipamiento de la radio y el de la televisión. The article narrates the story of UPVRadio and Universidad Politecnica Television University from 2000 to 2008, including the process of study, d…
Hydrogeomorphological analysis and modelling for a comprehensive understanding of flash-flood damage processes: the 9 October 2018 event in northeast…
2020
31 Pags.- 12 Figs.- 5 Tabls. © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License.
Mise en évidence d’une dynamique de fleuves de glace durant la glaciation ordovicienne par l’enregistrement géomorphologique
2007
On Contemporary Ice streams the most important factor controlling polar ice-sheet sheet stability and ice flowing occurs in ice streams. On Pleistocene Ice Sheet, Ice stream can be located using several geomorphologic criteria predict from known characteristic of contemporary ice streams, these criteria defining the conceptual Ice Stream land system model. But nowadays, during fossil glaciations, ice streams characterization is still poorly documented and only few studies illustrate fast ice velocity. In this work, we characterize geomorphological markers of ice stream activity in order to define the Ordovician ice stream glacial landsystem. The study area is located in Sahara from Niger to…