CRS4 Libro, Contributo in un libro

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https://hdl.handle.net/11050/56

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Mostra il contenuto di CRS4 Libro, Contributo in un libro per Autore "Cau, Pierluigi"

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    A Decision Support System based on the SWAT model for the Sardinian Water Authorities
    (2005) Lorrai, Eva Barbara; Cau, Pierluigi
    Sardinian Regional Authorities, such as Assessorato della Difesa dell’Ambiente, have the demanding problem of water management and protection. Targeted to their specific needs they use alternative applications and models for their specific tasks. Black box models, in the past, have been the most commonly used approach to describe the hydrological cycle. Despite their wide use, these models have shown severe limitations to take into account land use and climate changes. Physically based models can make better prediction when different combination of soil and land use, within the basin, have a significant effect on the hydrological cycle. The variety and complexity of alternative environmental problems found in the island, which vary from the impact of the agro-zootechnical to the industrial compartment, have suggested that empirical models are less suitable to predict the environmental dynamics at the catchment’s scale. Regional Authorities enact Regional Directives to enforce different European Directives, and no absolute limits can be drawn to separate their alternative field of application. The Piano di Tutela delle Acque Regional Directives aim to enforce water policy in terms of definition on where and how water resources must be used and what water protection actions need to be taken to improve water quality of rivers, lagoons, groundwater, lakes etc.. In this context, the hydrological physically based SWAT model has been chosen and applied to estimate both the water balance of the main catchments of the island and the impact of land management practices on downstream water bodies. The performance of the model has been evaluated on several stream flow monitoring gages against registered data.
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    A user friendly multi-catchments tool for the SWAT model
    (2005) Lorrai, Eva Barbara; Cau, Pierluigi
    A software system to manage SWAT results (bsb.dbf and rch.dbf) has been developed on a multi catchment scale. Regions such as Sardinia, Sicily, Portugal etc are, in fact, characterized by a large variety of ecosystems within complex catchments. The AVS2000 interface deals with one watershed at a time, but the aggregation of SWAT results about adjacent basins may be necessary for an integrated water resources management. To achieve this goal, an ArcView extension, called multi-catch.avx, has been developed. The extension allows the user to select the subbasins within the basins under investigation and obtain statistical reports of the model output, from the rch and bsb tables, in the form of charts, statistics and maps. The tool helps water managers in the demanding problem of water management by automating the post processing operation when dealing with many catchments within a region. Multi-catch.avx uses the bsb and rch files of all the projects and dynamically permits making time and spatial analysis at the widest scale and creating maps in the ArcView environment. A project view is created where all the watersheds under study are displayed along with their subbasins. The user can dynamically visualize and analyse the spatial distribution of a chosen model output for all the active subbasins within the given basin, at a monthly or yearly time resolution. Moreover the bsb file of each project is aggregated to represent the whole basin under study and statistical indicators such as mean, standard deviation etc. are calculated. The newly developed ArcView extension has been utilized to map, and analyze 15 Swat projects within the Sardinian Region.
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    Predicting groundwater salinity changes in the coastal aquifer of Arborea (Central Western Sardinia)
    (2005) Barrocu, Giovanni; Cau, Pierluigi; Soddu, S.; Uras, G.
    The area of Arborea, extending over roughly 70 km2, is located in the Northern Campidano plain (central-western Sardinia - Italy). The plain, that was formed in a tectonic trough of the Tertiary, is characterised by Quaternary deposits of fluvial, lacustrine, marine and eolian facies. The Quaternary formation is several hundred meters thick. The stratigraphic sequence, whose characteristics vary from one place to another, is generally represented by gravelly, sandy, silty and clayey deposits. The aquifer basin consists of two main units, a shallow phreatic aquifer (around ten meters thick) and a deeper semiconfined - confined unit, separated by a variable thickness aquitard. The system is recharged by rainfall, irrigation and by lateral inflow from the volcanic rock aquifers bordering the plain. Owing to inadequate water management policies, the Arborea coastal aquifer system has been contaminated by seawater intrusion as a result of overexploitation during the frequent droughts that affect Sardinia. Groundwater withdrawals have caused saltwater to encroach landward and upward toward the withdrawal points. Periodic monitoring, carried out for several years by the Department of Land Engineering at the University of Cagliari showed a varying degree of salt water intrusion along the coast. High electrical conductivity values were found mostly in the deeper aquifer, as it is locally overexploited, whereas lower values were recorded in the shallow phreatic aquifer. Nevertheless, in the shallow aquifer the extension of contaminated areas is larger than in the deep aquifer. In this work an extensive quality assessment of the data was performed to characterise the area overlying the Arborea aquifer system. In this context we set up a geographical information system and applied an environmental model to study the migration of the contaminants. A preliminary model, elaborated with the CODESA 3D code, was implemented to simulate the impact of land management (different groundwater abstraction schemes, artificial recharge etc.) on the salt dispersion process.
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    Una metodologia multivariabile per la calibrazione di alcuni parametri idrogeologici Portoscuso (Sardegna)
    (Asita, 2002) Cau, Pierluigi; Manca, Simone
    Nella presente nota si mostra l’applicazione di una metodologia di calibrazione per la valutazione di alcuni parametri idrogeologici. La metodologia si basa su un approccio multivariabile ed è sviluppata attraverso l’integrazione del GIS con modelli numerici. I dati, implementati in un GIS, costituiscono l’input di un modello tridimensionale agli elementi finiti (CODESA 3D) per la valutazione di fenomeni di trasporto di inquinanti in falda. La metodologia permette, variando opportunamente alcuni parametri del sistema attraverso l’analisi comparata degli scenari simulati, di determinare le configurazioni che meglio riproducono il sistema reale. In particolare si considera un algoritmo di ottimizzazione, implementato in Arcview, che minimizza gli scarti tra le misure campionate e quelle simulate. L’insieme delle configurazioni in grado di riprodurre il comportamento del sistema è poi discusso in termini probabilistico−statistici. Obiettivo del presente lavoro è, oltre alla parametrizzazione del sistema fisico in studio, l’implementazione all’interno del GIS di una metodologia automatica di gestione e analisi dei dati simulati. Il sito su cui viene testata la procedura è un settore della piana di Portoscuso (Sardegna Sud Occidentale) inquinata da residui inorganici provenienti da industrie metallurgiche e chimiche.