1,721,185 research outputs found
VALUTAZIONE DEGLI IMPATTI DEL CAMBIAMENTO CLIMATICO SULLA PERFORMANCE DELL’INVASO DI RIDRACOLI
No full textClimate change represents one of the most discussed challenges at the centre of the scientific, political and socio‐cultural debate today. In Italy, in recent years, the perception of the increase in temperatures and variation in precipitation, both in frequency and intensity, foreshadow a risk scenario feared by the stakeholders in the water services, as any period of prolonged water scarcity could put water supply
systems out of service.
The tools implemented in this work, developed in collaboration with Romagna Acque ‐ Società delle Fonti S.p.A., are capable of assessing the availability of the water resource over the future period, according to 7 different chains of climate models and two different climate change scenarios. The first one is considered
more optimistic as it results from the implementation of controlling policies to reduce greenhouse gases emission rates (RCP4.5), whereas the second one represents the no‐policy baseline approach (RCP8.5). Thus, scenario‐based modelling allows us to estimate the impact of future climatic variations
on the water supply system of Romagna, in Italy. Moreover, a theoretical‐statistical analysis is first conducted in order to improve climate models’ outputs, which otherwise cannot be used at local‐scale applications, due to the presence of non‐negligible biases in the original signals. The technique adopted, known as Quantile Mapping, considering only the gap between the frequency distributions of climatic
variables, observed and simulated, on the same historical reference period, allowed to obtain the same corrected climatic forcings in the future period. These series have constituted the necessary input, together with evaporation, of an accurate modelling chain, consisting of a rainfall‐runoff model that continuously feeds the management model of the Ridracoli reservoir. In this way, it was possible to obtain an estimate
of the future surface runoff at the dam closure section and in correspondence with the weirs placed on the rivers connected to the Ridracoli reservoir and consequently a sufficiently reliable and realistic forecast of future drinking water supply, up to the year 2100, for both climatic scenarios considered.
The study presented illustrates an analysis path that can be extended to other regulation reservoirs located in the Euro‐Mediterranean area, configuring itself as a useful approach for the definition of the tools required in a decision support system. In fact, with such tools, water system managers are capable of evaluating the effects of possible adaptation strategies to the expected climate scenarios, with the final
aim of limiting as much as possible periods of future deficits in the water supply systems
Assessing the uncertainty of rainfall-runoff simulations through a meta-Gaussian approach
No full textGeostatistical prediction of flow-duration curves
Full text linkWe present in this study an adaptation of Topological kriging (or Top-kriging), which makes the geostatistical procedure capable of predicting flow-duration curves (FDCs) in ungauged catchments. Previous applications of Top-kriging mainly focused on the prediction of point streamflow indices (e.g. flood quantiles, low-flow indices, etc.). In this study Top-kriging is used to predict FDCs in ungauged sites as a weighted average of standardised empirical FDCs through the traditional linear-weighting scheme of kriging methods. Our study focuses on the prediction of period-of-record FDCs for 18 unregu-
lated catchments located in Central Italy, for which daily streamflow series with length from 5 to 40yr are available, together with information on climate referring to the same time-span of each daily streamflow sequence. Empirical FDCs are standardised by a reference streamflow value (i.e. mean annual flow, or mean annual precipitation times
the catchment drainage area) and the overall deviation of the curves from this reference value is then used for expressing the hydrological similarity between catchments and for deriving the geostatistical weights. We performed an extensive leave-one-out cross-validation to quantify the accuracy of the proposed technique, and to compare it to traditional regionalisation models that were recently developed for the same study region. The cross-validation points out that Top-kriging is a reliable approach for predicting FDCs, which can significantly outperform traditional regional models in ungauged basins
Evolution of flood risk over large areas: Quantitative assessment for the Po river
Full text linkThe worldwide increase of damages produced by floods during the last decades strengthens the common perception that flood risk is dramatically increasing due to a combination of different causes, among which climate change is often described as the major driver. Nevertheless, the scientific community is increasingly aware of the role of the anthropogenic pressures (e.g. steady expansion of urban and industrial areas in dyke-protected floodplains) that may strongly impact the flood risk in a given area by increasing potential flood damages and losses (i.e. so called "levee effect"). The scientific literature on quantitative assessments of the "levee-effect" or robust methodological tools for performing such assessments is still sparse. We refer to the dyke-protected floodplains of the middle and lower portion of River Po (Northern Italy), a broad geographical area (~46,000km2) with two specific research questions in mind: (i) has the flood risk increased over the last half century? And, if so, (ii) what are the main drivers of this change? First, we assess the flood-hazard evolution by analyzing three long series of daily streamflow available at different gauging stations. Secondly, we quantitatively assess the temporal variability of the flood exposure and risk by looking at the evolution in time of anthropogenic pressures (i.e. land-use and demographic dynamics observed from 1950s). To this aim, we propose graphical tools (i.e. Hypsometric Vulnerability Curves - HVCs) that are suitable for assessing vulnerability to floods over large geographical areas. Our study highlights the absence of statistically significant trends in annual statistics of the observed streamflow series and a stable population density within the dike-protected flood-prone area. Nevertheless, the proposed flood-vulnerability indexes show a significant increase of the exposure to floods in residential settlements, which has doubled since the 1950s
Optimal operation of pressurised irrigation distribution systems operating by gravity
No full textOn-demand pressurized irrigation distribution networks (IDN) operating by gravity may face pressure
failures especially during the peak period. Several methods have been developed for irrigation sectoring where farmers are organized in turns. In general, the optimization methods used for pressurized systems consider, in the formulation of the problem, energy saving as objective function, which is not suitable for gravity-fed networks. In this study, an optimization model for pressurized IDN fed by gravity was developed to provide an optimal operating strategy based on irrigation periods. The model uses genetic algorithm to assign an irrigation period to each hydrant taking into account the minimization of pressure deficit at the most unfavorable hydrant of the network. The method is applied to a large scale irrigation distribution network in Italy. It shows to significantly improve the hydraulic performance of the network by insuring a satisfactory pressure at all hydrants, under the actual peak demand as well as higher water demands
Flood-risk mitigation in the Soliette river basin: an international cooperation initiative (Haiti, Dominican Rep., Italy)
Full text linkIsla Hispaniola (Haiti and the Dominican Republic), one of the poorest regions of the planet, has
repeatedly been hit by catastrophic natural disasters that caused incalculable economic losses and killed
thousands of people. One striking example is the disastrous flood-event that occurred in the transnational
basin of River Soliette on May 24th, 2004. The event was produced by a severe tropical storm originated
over the Caribbean Sea from an intense low-pressure system, and killed over 1000 Haitian and
Dominican people, wiping out a number of rural villages. The General Direction for Development and
Cooperation of the Italian Department of Foreign Affairs funded through the Istituto Italo-Latino
Americano (IILA, www.iila.org) an international cooperation initiative (ICI), coordinated and directed by
the University of Bologna. The initiative involved Haitian and Dominican institutions and consisted in
two main components: (a) institutional capacity building on flood-risk management and mitigation
measures and policies; (b) hydrological and hydraulic analysis of the May 2004 flood event aimed at
formulating a suitable and affordable flood-risk mitigation plan. The second component of the
cooperation is the main focus of this paper and in particular, starting from some logistical and technical
constrains, a topographic survey based on GNSS technology that enabled us, in a short time, to survey
river cross sections and construct Digital Elevation Models for two areas where to conduct numerical
hydraulic modelling and to pre-design hypothetic flood-risk mitigation measures. The paper reports and
discusses the main phases of the project
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
- …
