Laminazione riutilizzo sollevamento

Revisionato il 11/09/2026

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Appunti di Idraulica. Analisi delle opere di laminazione delle piene, del riutilizzo delle risorse idriche e degli impianti di sollevamento. Il documento tratta criteri di progettazione, …

Esame Idraulica

Facoltà Ingegneria

Dal corso del Prof. Ursino Nadia

Università Università degli Studi di Padova

A.A. 2022-2023

97 pagine

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Estratto del documento

S =surface depression

Reliability Theories

Analytical models formulated

with derived probability

distribution theory, for screening

level analysis

Reliability

detention

systems

The probability density functions of rainfall characteristics are

exponential:

f =ζe

−ζh

f =λe

−λt

f =ψe −ψb

h=rainfall depth

t=rainfall duration

b=interstorm interval

Are independent random variables

The distribution parameters are:

ζ=inverse of expected value of rainfall depth,

λ=inverse of expected value of rainfall duration,

ψ=inverse of expected value of rainfall inter-storm interval.

Detention: f=0

Assuming as certain that the network

can transfer water from the impervious

sub-catchment to the tank, and that

the overflow divider performs correctly,

only the detention system is subject to

failure.

Initial condition

In applying the analytical probabilistic approach to assess the

efficiency of a stormwater detention system, it is important to

obtain the storage facility’s initial condition, e.g., the

available stormwater storage capacity of the facility.

Depending on the conditions preceding a random rainfall

event, the storage facility may be completely or partly

empty when the rainfall event starts.

Simplifying assumptions previously adopted in

literature

1. The storage facility is completely full at the end of

the rainfall event preceding the random rainfall

event under analysis. [ Howard’s conservative

assumption (Howard 1976)] .

2. The storage facility is completely empty when the

analyzed random rainfall event starts

Simplifying assumptions previously adopted in

literature

1. The storage facility is completely full at the end of

the rainfall event preceding the random rainfall

event under analysis. [ Howard’s conservative

assumption (Howard 1976)] .

2. The storage facility is completely empty when the

analyzed random rainfall event starts

Sd=storage depression =0

VASCHE DI LAMINAZIONE

Risk of overflow R is estimated, as the probability that either the

rainfall volume is imp h >V or that two consecutive rainfall events

occur in a short period of time. At the beginning of the second rainfall

event, tank storage capacity is impQ b=V’ <V and rainfall volume is

0 s s

imp h> V’s

Under the most conservative assumption that the reservoir is full at

the end of the first of two consecutive rainfall events,

Rf =P[b≥Vs/Q imp]·P[h>Vs/imp]+P[b<Vs/Q imp]·P[h>Q b]

0 0 0

Rf =P[b≥Vs/Q imp]·P[h>Vs/imp]+P[b<Vs/Q imp]·P[h>Q b]

0 0 0



 

 h

p ( h ) e

h 

 

 b

p (

b ) e

b V s

Q imp

  

       

     

   

b h b h

R e e dh db e e dh db

f V V 0 bQ

s s 0

Q imp imp

0  

 

V



  

s  

Q  

imp Q

   

R e 0

f      

Q Q

0 0

SE I VOLUMI ACCUMULATI NELLA VASCA DI

LAMINAZIONE VENGONO RIUTILIZZATI PER GLI USI

CONSENTITI, E’ NECESSARIO VALUTARE IL RISCHIO

CHE I VOLUMI RISULTINO INSUFFICIENTI ALLA

LAMINAZIONE E/O AL RIUTILIZZO

Ursino, 2015 Dimensionless

parameters

Rainfall model

ζ = inverse of expected value of rainfall depth and

λ = inverse of expected inter-storm interval

Dimensionless

parameters

The storage facility is completely full at the end of the rainfall event

preceding the random rainfall event under analysis. [ Howard’s conservative

assumption Risk of overflow Dimensionless

parameters

The storage facility is empty at the end of the dry period preceding the

random rainfall event under analysis. [ Howard’s conservative assumption

Risk of water scarcity Dimensionless

parameters

Il volume della

vasca V , influenza

influenza piuttosto il

peso relativo dei

due addendi che

compaiono nelle

espressioni di

rischio

RISK ANALYSIS OF

RAINWATER HARVESTING

SYSTEMS AROUND THE

WORLD

Simplifying assumptions previously adopted in

literature

1. The storage facility is completely full at the end of

the rainfall event preceding the random rainfall

event under analysis. [ Howard’s conservative

assumption (Howard 1976)] .

2. The storage facility is completely empty when the

analyzed random rainfall event starts

ESEMPI DI SISTEMI DI RIUTILIZZO

Efficiency is an increasingly good estimate of the system reliability as the number of

years of observation increases.

Jordan averaged monthly Domestic use Abdulla

precipitation data et al., 2009

Brazilia(Brazil) Dayly rainfall -30 washing vehicles Sanches

years Fernandes et al.,

2015

South Africa data forecasted houshold water Mwenge Kahinda

by 6 global requirements et al., 2010

circulation models

Iran Dayly rainfall -50 Reuse systems for Mehrabadi

years residential et al, 2013

buildings

Italy Dayly rainfall -30 Reuse systems for Palla et al., 2011

to 100 years residential

buildings

Australia Monthly average Reuse systems for Zhang et al., 2009

rainfall -80 years residential

buildings

Design is usually

performed with

reference to tank

efficiency

In high demanding

scenarios there will

be a marked

dependence of the

RWH system

efficiency on the

water demand

(Fernandes et al.,

2015).

non-dimensional

analysis

demand ratio: ratio

between annual

demand and annually

collected rainwater

storage fraction: ratio

between storage

capacity of the

Anteprima

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