IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Water resources and hydroinformatics : Stochastic approach for stormwater tank assessment
Stochastic approach for stormwater tank assessment
tion tanks are frequently used as a structural measure for mitigating impacts of combined and
separated sewer overflows from urban catchments into receiving water bodies. The dimension of these capacities
depends on the climate pattern and the sewer system behaviour, and it can be estimated by using continuous simulation
or probabilistic approaches. The latter are generally based on a stochastic model which is able to fit the statistical
pattern of observed rainfall records and on an urban hydrology model that transforms rainfall in sewer discharge. A key
issue is the identification of the optimal structure of the stochastic rainfall model.
In this paper a conceptual stochastic model of rainfall is proposed in which storms occur in a stochastic process, where
each storm has a random lifetime. Different events are identified through the definition of an Inter-Event Time Duration
(IETD), that is the duration of the dry period between two consecutive storms. Point processes are frequently applied
where rainfall events are represented through the occurrence of rectangular pulses, which are governed by specific
descriptors (volume, duration and IETD). The paper focuses on the analytical derivation of the Probability Density
Function (PDF) of the number of overflows as a function of the storm-water capacity. This is performed by using the
derived probability distribution approach. The number of overflows is used as a performance indicator of the tank
effectiveness in mitigating the environmental impacts on natural water bodies (sea, rivers, lakes etc.) in terms of both
quantity and quality. The proposed approach is applied to two different sites located in Campania Region, in Southern
Italy. For both locations the Pareto-2 and the Gamma PDFs show good results in fitting the rainfall depth and duration at
varying the IETD, and they perform better than the Weibull and the Exponential model, which were widely used in past
studies. Furthermore, it turned out that Fatigue Life or the Log-Gamma PDFs are able to provide the best fit for the
IETD. Finally, the extension of the proposed model to different hydrological conditions is discussed.Form Required :
File Size : 600,338 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Water resources and hydroinformatics
Date Published : 20/08/2015
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