Search results for " Rivers"

Wasserstand und Eisbedeckung der Düna bei Riga

1887

Atsevišķs novilkums no: "Bericht über die Vorarbeiten für die systematische Entwässerung und Reinigung der Stadt Riga".

Flash-flooding of Ephemeral Streams in the Context of Climate Change

2021

Ephemeral streams, which are more extended than expected, entail a significant flood risk. Historically they have been underestimated due to their intermittent flow and the lack of knowledge on their hydro-geomorphology. Currently, European legislation recognizes their associated risk and supports research into them, adapting the scale and methodology to their characteristics. Based on the compilation of various works carried out in four Valencian catchments (Eastern Spain), this paper approaches the key questions of rainfall-runoff conversion and flood generation in ephemeral streams, taking into account their hydro-geomorphological specificity. Moreover, the consequences which derive from…

Cross sectional flow in a meandering laboratory channel with vegetated bed

2016

As it is known, the outer-bank of a meander wave is considerably vulnerable to the erosion processes. Literature indicates that cross-stream circulation strongly affects the redistribution of the downstream velocity and boundary shear stress in curved channels. In steep outside bends, beside a central-region circulation cell, a counter-rotating circulation cell often forms in the upper part of the outer-bank region. Accurate understanding of the role of these circulation cells on velocity redistribution in bends is important to define protective measures of the outer-bank. Literature also shows that vegetation could modify flow velocity and turbulent structure. This work reports preliminary…

Phytoplankton in the Physical Environment

2010

Evaluating anthropogenic impacts on naturally stressed ecosystems: Revisiting river classifications and biomonitoring metrics along salinity gradients

2019

Naturally stressed ecosystems hold a unique fraction of biodiversity. However, they have been largely ignored in biomonitoring and conservation programmes, such as the EU Water Framework Directive, while global change pressures are threatening their singular values. Here we present a framework to classify and evaluate the ecological quality of naturally stressed rivers along a water salinity gradient. We gathered datasets, including aquatic macroinvertebrate assemblages and environmental information, for 243 river locations across the western Mediterranean to: a) gauge the role of natural stressors (salinity) in driving aquatic community richness and composition; b) make river classificatio…

Rainfall and water yield in Macizo del Caroig, Eastern Iberian Peninsula. Event runoff at plot scale during a rare flash flood at the Barranco de Ben…

2021

[EN] Floods are a consequence of extreme rainfall events. Although surface runoff generation is the origin of discharge, flood research usually focuses on lowlands where the impact is higher. Runoff and sediment delivery at slope and pedon scale receiving much less attention in the effort to understand flood behaviour in time and space. This is especially relevant in areas where, due to climatic and hydrogeological conditions, streams are ephemeral, so-called dry rivers (¿wadis¿, "ramblas" or ¿barrancos¿) that are widespread throughout the Mediterranean. This paper researches the relationship between water delivery at pedon and slope scale with dry river floods in Macizo del Caroig, Eastern…

Contatti culturali, identità e popolamento nel territorio imerese

2016

Il lavoro prende in considerazione il problema dei rapporti tra coloni greci e comunità indigene nel territorio di Himera, sulla base dei risultati della prospezione archeologica condotta per tre decenni nelle valli dei fiumi Imera settentrionale, Torto e S. Leonardo. Vengono esaminati gli elementi di cultura materiale che permettono di definire i modi dell'interazione culturale tra coloni e indigeni, nonché di ricostruire i paesaggi politici, socio-economici e il paesaggio del sacro nelle diverse aree indagate e nei diversi comprensori. La ricerca infatti permette di delineare, oltre alle usuali organizzazioni insediative e agricole della chora politiké e della éremos chora, anche articola…

Geochemical investigation of trace metal pollutants in the Oreto river, Palermo (Italy)

2022

In the past, three main rivers, named Kemonia, Papireto and Oreto, were present in the plain of Palermo, in northwestern Sicily. Today, only the latter one has been preserved from the unregulated urban expansion. Fortunately, over the last ten years, attention and consciousness towardsthe Oreto river and its delicate ecosystem has grown considerably, also thanks to many associations and citizens’ committees involved in protecting, preserving and valorising the precious area. In this context, our study is focused on a hydrogeochemical investigation of its surface water quality. The Oreto river flows for about 20 km within a catchment area of about 130 km2. Over the past three years, numerous…

Efectos de una crecida en un cauce antropizado. La riada del Palancia de octubre de 2000

2011

[EN] In October of 2000, the Palància River underwent a major flood, which substantially modified the morphology of the river channel. These changes took place on a river bed previously modified by public works aimed at cleaning and simplifying the river section. The flood partially restored the braided morphology, reconstructing bars and channels. Moreover, river incision processes increased, particularly downstream the Palància bridges. This process reveals a sedimentary deficit caused by reservoirs; land use changes and gravel mining. The aim of this work is to describe these processes of change and to analyze the morphosedimentary consequences, through the interpretation of aerial photo…

Linking the Molecular Signature of Heteroatomic Dissolved Organic Matter to Watershed Characteristics in World Rivers

2015

Large world rivers are significant sources of dissolved organic matter (DOM) to the oceans. Watershed geomorphology and land use can drive the quality and reactivity of DOM. Determining the molecular composition of riverine DOM is essential for understanding its source, mobility and fate across landscapes. In this study, DOM from the main stem of 10 global rivers covering a wide climatic range and land use features was molecularly characterized via ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). FT-ICR mass spectral data revealed an overall similarity in molecular components among the rivers. However, when focusing specifically on the contributi…