1,720,961 research outputs found
Monitoring suspended sediment transport in two moutainous river basins: the Carapelle and the Celone (Apulia, Italy)
No full textSediment load quantification is an important task in river basin management, as it provides the order of magnitude of soil loss. Yearly sediment loads were quantified in two river basins of the Apulia region, the Carapelle (506 km(2)) and the Celone river basin (72 km(2)). For the Carapelle river basin, streamflow and suspended sediment concentrations (SSC) were monitored from 2007 to 2011 with an infrared optical probe and suspended sediment load at the yearly basis was quantified by integration of instantaneous flux. For the Celone river, continuous measurements of streamflow and discrete measurements of SSC taken, from 2010 to 2011, in all hydrological conditions (high, normal and low flow) were used to develop sediment rating curves. In particular, different sediment rating curves were developed for the entire dataset and three subsets of data identified based on the hydrological conditions and loads were computed with and without a backtransformation correction factor. At the Celone river gauge, annual specific sediment load ranged from 2.4 t ha(-1) yr(-1) to 6.06 t ha-1 yr(-1). At the Carapelle river gauge, the annual specific sediment load ranged from 0.9 t ha(-1) yr(-1) to 7.45 t ha(-1) yr(-1). The results of the present study show that the hydrological regime is the key factor in sediment transport in the Celone and Carapelle basins and that the duration of the sampled period, and its characteristics (wet or dry) may have a great impact on sediment loads
Characterizing flow regime and its alterations in an intermittent river: the Canale d’Aiedda case study
No full textAnthropogenic activities, such as waste water treatment plants dis-
charges (WWTPs), impact the natural river regime. The assessment of the “im-
pacted” and “un-impacted” hydrological conditions is of paramount importance
for the river management. Methodologies for characterizing flow regime and its
alterations are based on streamflow data recorded over a long period. Data re-
quirements may be a limitation in regions where the recorded data are not avail-
able or poor (i.e. short time series, presence of gaps). Hydrological models,
such as the Soil and Water Assessment Tool (SWAT), may be used to generate
long-term time series of daily or monthly streamflow.
In this work, an approach to characterize the flow regime of an intermittent riv-
er and to assess its alterations using the SWAT model is defined. The aims are:
(i) adapt SWAT for simulating daily streamflow in the Canale d’Aiedda river
(Italy), (ii) characterize its flow regime, and (iii) assess the hydrological regime
alterations due to WWTPs.
The flow regime was characterized by using several hydrological indicators,
based on the long-term time series of modeled daily streamflow. Hydrological
regime classification of the river reaches receiving wastewaters from WWTPs
shifted from intermittent to perennial. The components of the low flow (1-, 3-,
7-, 30-, and 90-day minimum flow, zero-days) and the monthly flow recorded
in summer were severely altered. The concept of “zero-flow threshold”, defined
on field observations was introduced to improve the model results. This study
provides a contribution to the significant topic of the management of intermit-
tent rivers under the Mediterranean climate
Suspended sediment load estimation using sediment rating curves in two intermittent rivers
No full textThe determination of suspended sediment (SS) load is essential for understanding
soil erosion magnitude. This study quantifies SS loads in two mountainous river
basins in Apulia (S-E, Italy): the Carapelle (506 km2) and the Celone (72 km2).
Continuous and discrete sampling strategies were used to monitor streamflow (Q)
and SS concentrations (SSC) across diverse hydrological conditions. Sediment
rating curves were developed to rectify lacks in daily observed SSC time series.
For the Carapelle River, continuous SSC and Q monitoring was conducted from
2007 to 2011 using an optical probe and an ultrasonic stage recorder. In the Celone
River, a comprehensive dataset of continuous Q measurements and discrete
SSC measurements was collected from 2010 to 2011. Sediment rating curves
were tailored for three subsets of data representing high, normal, and low flow
conditions, while addressing missing SSC data. Annual specific sediment load
ranged from 2.4 to 6.06 t ha-1 yr-1 for the Celone River and 0.9 to 7.45 t ha-1 yr-1
for the Carapelle River. Over 80% of the SS load was transported during highflow
conditions, while less than 1% occurred during low-flow conditions. The
findings highlight the importance of the hydrological regime in regulating sediment
transport in hilly Mediterranean rivers and show that the length and characteristics
of the sample period can significantly impact the accurate estimation
of sediment load
Evaluating flow regime alterations due to point sources in intermittent rivers: A modelling approach
Full text linkHydrological regime alterations may strongly influence river morphology, water quality, and river ecosystem. The present paper aimed to define an integrated modelling framework for analysing the hydrological regime alterations induced by point sources (PSs) discharges in data-limited regions through two case studies: the Canale d'Aiedda (Italy) and Nil wadi (Algeria). Long time series of daily streamflow in un-impacted and impacted (PSs discharges) conditions were generated by applying the Soil and Water Assessment Tool model and the hydrological regime was characterised by using several hydrological indicators. Flow regime alterations due to PSs were assessed with the range of variability approach. Results showed that the PSs induced alterations of some flow regime components (magnitude, duration, and timing). Hydrological regime classification of the river reaches receiving wastewaters from PSs shifted from intermittent to perennial. All the components of the low flow (1-, 3-, 7-, 30-, and 90-day minimum flow, zero-days) and the monthly flow recorded in summer were severely altered. Minor hydrological alterations were assessed for high flow components (1-, 3-, 7-, 30-, and 90-day maximum flow) and mean monthly flow in the wet period. The tuning of minimum flow was found to shift later in the year. This study may support river ecologists in the ecological status evaluation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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