1,721,018 research outputs found
Hydrologic and environmental impacts of imperviousness in an industrial catchment of northern Italy
No full textThe increase of imperviousness due to urbanization creates adverse effects on the hydrological and environmental processes in a catchment. The increase in impervious areas leads to a higher runoff peak flow and stormwater pollution, even for a short duration of low- intensity rainfall. The present study focuses on the Bivio Vela catchment, an urban catchment of Pavia in northern Italy. This paper em- phasizes both experimental and modeling approaches to the rainfall-runoff process and pollutant dynamics on the catchment surface and in the combined sewer system, considering significant increases in impervious area. Recent and future catchment developments caused the conversion of approximately 33% of the total area from nonurban pervious area to impervious area. The study also deals with the performance assessment of the wet-weather control system of the catchment, introducing simple indicators that account for the requirements of the urban drainage system and treatment plant. Imperviousness associated with urbanization in the catchment is invariably reflected in the receiving river flow regime and water quality. The simulation results indicate that the annual number and duration of sewer overflows and volume, peak flow, and pollutant mass discharged into the river have increased to different degrees due to urban expansion during the recent period and will continue to increase as urban areas increase in the future. The impact of urbanization on rainfall runoff and water quality should therefore be considered for effective urban and water infrastructure planning. The methodological approach and the proposed performance indicators, which take advantage of experimental data and are suitable for complex urban drainage systems, are original and promising for their help in formulating policy guidelines and intervention strategies that minimize the negative effects of urbanization on both the water environment and the treatment plant
Il controllo degli scarichi fognari di tempo di pioggia mediante vasche di prima pioggia: aspetti progettuali e gestionali.
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Trends in long daily rainfall series of Lombardia (Northern Italy) affecting urban stormwater control
No full textAnalyses of six daily rainfall series (Milano, Bergamo, Brescia, Como, Mantova and Sondrio) are used to assess trends in yearly precipitation behaviour (precipitation height and number of wet days; precipitation height and number of wet days for different classes of daily precipitation; precipitation height related to 1 wet day; number of dry days between wet days) over Lombardia, Northern Italy. The time series analysis was performed with two non-parametric rank based tests: the Mann Kendall test and Sen’s estimator of slope. Also a new and advantageous procedure that combines a time series model and Bayesian statistics through the Markov Chain Monte Carlo (MCMC) method of Gibbs sampling is adopted to model trends. Globally, the different methods detect the same tendencies. The results point toward a significant decreasing trend in the annual number of wet days and an increasing tendency in the mean and maximum precipitation height related to 1 day, with a generalized increasing tendency for the number of dry days between wet days. These trends affect the rainfall runoff process and the pollutant dynamics on urban areas and in drainage systems and could provoke a significant efficacy reduction of existing urban quantity and quality control systems
Innovative and Reliable Assessment of Polluted Stormwater Runoff for Effective Stormwater Management
No full textThis article examines the pollution dynamics in urban wet-weather runoff, addressing the statistical characterization and systematic classification of water quality characteristics as key aspects of sustainable and effective urban stormwater quality control and treatment measures. A reliable first flush methodology is applied to discrete water quality data of different pollution parameters from an Italian database for the identification of the Bivio Vela catchment’s representative evolution of mean concentrations and the assessment of the required runoff volume to reduce stormwater pollutant concentrations to background levels. A comparison is carried out between results from two catchments with different land use types (industrial versus residential) and the complexity of the sewerage system, highlighting challenges in tracking pollution trends and delineating peculiar dynamics of different quality parameters in a specific geographic context. Despite appreciably different pollutant dynamics, both catchments achieve background levels for all the examined parameters after 6 mm runoff. The outcome of the analysis has clear implications for the design approach of sustainable stormwater management practices
Qualità e controllo delle acque di dilavamento di infrastrutture viarie
No full textLa memoria, preliminarmente, definisce le strade e le loro pertinenze, con riferimento al Decreto Legislativo 30/04/1992 “Nuovo Codice della Strada e presenta una sintesi dei criteri compositivi della piattaforma stradale fissati dal Decreto Legislativo 5/11/2001 “Norme Funzionali e Geometriche per la Costruzione delle Strade”. Successivamente, indaga i principali agenti inquinanti delle infrastrutture viarie, le loro fonti di emissione e i meccanismi che ne governano la dinamica. Sviluppa, infine, un’analisi critica delle soluzioni proposte in letteratura per mitigare l’inquinamento veicolato dalle acque di dilavamento di strade e parcheggi urbani, autostrade e strade extraurbane di grande traffico, pertinenze stradali di servizio e di esercizio. In particolare, evidenzia la rilevanza dei diversi sistemi di controllo in termini di affidabilità funzionale e efficienza gestionale
Impatto degli scarichi di tempo di pioggia sulla qualità dei corpi idrici ricettori e strategie di mitigazione
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