Analysis of Rainfall Intensities and Tides for Storms Water Management in Mumbai

7/31/2019 Analysis of Rainfall Intensities and Tides for Storms Water Management in Mumbai

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20th December, 2009

V.J.T.I., Mumbai

National Seminar on Sustainable

Environment

Analysis of Rainfall Intensities and Tides for Storm

Water Management in Mumbai


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BRIMSTOWAD

r an um a orm a er ra nage as er an

-

(now MWH) in association with AIC India Private Limitednves ga e n- ep , var ous aspec s o s orm wa er ra nage

system in Mumbai

ormu a e proposa s or eve opmen an ma n enance o esystem

rov e a programme o cap ta wor s -

crores at 1993 level to alleviate chronic flooding problems in

Due to limitations of funds, very few of the recommendations

were mp emen e .

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Unprecedented flooding in Mumbai on 26/27 July

2005. Total rainfall manuall measured at Santacruz

was 944.2mm

190.3

150

200

mm)

100.2100.4

60.242.5

48.250

100

Rainfall(

0

8:00

9:00

10:00

11:00

12:00

13:00

14:00

15:00

16:00

17:00

18:00

19:00

20:00

21:00

22:00

23:00

0:00

1:00

2:00

3:00

4:00

5:00

6:00

7:00

8:00

Time (hrs)

Plot of Rainfall Event on 26/27 July 2005

overnment o a aras tra appo nte a act n ng

Committee (FFC) to investigate causes and suggest

recommen at ons.

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The Municipal Corporation of Greater

study to includeUpdated hydraulic modeling

oo ng so u onsEngineering designs

Economic analysis

4


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Hydraulic Design of Storm Water Drainage

Rational Method

5


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Rational Method

=Where, Q = Runoff; C = Runoff Coefficient;

= =

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Intensity Duration Frequency (IDF)

=

= c

i = a/tn

W ere, = Intens ty o Ra n a , mm r

t = Duration, minutes

= eturn per o n years

a, b, c, d and n are Constants

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yp ca a n a ar rom

Automatic Rainfall Gauge

8


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IDF Relationships for Colaba and Santacruz

Frequency Range Intensity (mm / hour)

6 months to 1 year

458.98 FREQ0.2423

(DUR + 18.16)0.7182264.12 FREQ0.2272

(DUR +4.50)0.5609

1.25 to 2 years113.53 FREQ0.1914

(DUR +1.57)0.3819338.06 FREQ0.2149

(DUR +10.75-)0.6011

2.25 to 3 years. .

(DUR -0.22)0.3739. .

(DUR +16.99)0.6754

80.99 FRE 0.2041 165.39 FRE 0.4697. o years

(DUR 1.93)0.3246 (DUR +19.44)0.6433

5 to 10 ears 105.44 FREQ0.0898

7606.12 FREQ0.5680

Where,

FREQ is Frequency in months;

. . . .

DUR is Duration in minutes* Chawathe et. al., Journal Institute of Engineers (India), Vol. 58, October 1977

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Rainfall Measuring Gauge Stations

Thane District

NoDevelopment

Zone

NationalPark

WesternSuburbCatchments

ThaneCreek

NoDevelopmentZone

EasternSuburb

Available(1969-2008)Sanacruz

atc ments

City

ArabianSea

DataAvailable(1969-2008)Colaba

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IDF Curves for Colaba200.00

ReturnPeriod

150.00

1 in 1 year

1 in 2 year

1 in 5 year

1 in 10 year1 in 15 year

n year

2 in 1 year

100.00

m/hr)

50.00

Intensity(

11

0.00

0 5 10 15 20 25

Duration (hours)


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IDF Curves for Santacruz200.00

ReturnPeriod

150.00

1 in 1 year

1 in 2 year

1 in 5 year

1 in 10 year

1 in 30 year

2 in 1 year

100.00

m/hr

In

tensityin

.

12

0.00

0 5 10 15 20 25Duration in hours


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Conversion of IDF Curves to Chicago Curves

Consider IDF curve for a iven fre uenc

Use INFOWORKS Software

Input a, b, c for the given frequency

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General Form of Chicago Curve

i = F(t) = a [(1-c)t + b]+

Where,

i is the Intensity mm/hr;

a, b and c are constants; For a specificfrequency

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Design Hyetographs500

400 2in1

1in1

ReturnPeriod

300

m/hr)

n

200Intensity(

100

0

Chicago Curves for Colaba for 4 hour duration 15

0 1 2 3 4

Duration(hours)


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600

1in5

1in10

1in15

500

m/hr)

300

400

Intensit

y(

200

100

Chicago Curves for Colaba for 4 hour duration 16

0 0.5 1 1.5 2 2.5 3 3.5 4

Duration (hours)


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4002in1

1in1

ReturnPeriod

300

m/hr)

1in2

200Intensit

y(m

100

Chicago Curves for Santacruz for 4 hour duration 17

0 1 2 3 4

Duration (hours)


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1000

1in5

1in101in15

ReturnPeriod

800

mm/hr)

1in30

600

Intensity(

200

0

Chicago Curves for Santacruz for 4 hour duration18

0 1 2 3 4Duration (hours)


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Tides

Rise and fall of sea levels caused b

combined effects of rotation of earth and gravitational

forces exerted by moon and sun

Most coastal areas experience two daily high and two daily

low tides.

Tide levels are influenced by wind, precipitation, currents ofwater and lobal tem erature variation.

The two high waters HH and HL are not of the same height.

imilar is the case for two low water LL and LH

Around new and full moon, the tidal range (difference between

moon is at first quarter or third quarter the tidal range isminimum Nea Tide 19


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Tidal Anal sis

Daily Tide Levels; High high (HH), High low (HL),

Low high (LH) and Low low (LL) were collected.

*Apollo Bunder: 1986-2008 (Predicted)

* -

* *A ollo Bunder: 2005 and 2006 Actual observed

*Source: Maharashtra Maritime Board, Mumbai* *Source: Survey of India, Dehradun

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Tide Levels Measuring Gauge Stations

ThaneDistrict

NoDevelopment

Zone

NationalPark

ThaneCreek

EasternSuburbCatchments

DataAvailable(2003-2008)

No

DevelopmentZoneWestern

SuburbCatchments

Bandra

ArabianSea

City

Data

Available

Data

-Trombay

City North-EastCatchments

(1986-2008)

ApolloBunder

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Typical Average Predicted Tide Levels from

Years MonthsHH

(m above THD)

HL

(m above THD)

LH

(m above THD)

LL

(m above THD). . . .

July 26.005 25.504 23.812 22.907

August 25.917 25.494 23.689 22.917

September 25.907 25.533 23.563 22.928

1987 June 26.079 25.483 23.816 22.867

July 26.048 25.509 23.725 22.894August 25.946 25.555 23.620 22.882

. . . .

1988 June 26.096 25.480 23.837 22.832

July 26.095 25.554 23.708 22.811

August 26.025 25.646 23.515 22.818September 25.956 25.591 23.488 22.810

1989 June 26.070 25.417 23.777 22.811

July 26.053 25.471 23.755 22.812

22

September 25.910 25.516 23.448 22.878


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Typical Average Predicted Tide Levels from

Years MonthsHH

(m above THD)

HL

(m above THD)

LH

(m above THD)

LL

(m above THD). . . .

July 26.262 25.596 23.585 22.495

August 26.223 25.677 23.410 22.594

September 26.122 25.781 23.300 22.736

2005 June 26.261 25.546 23.609 22.642

July 26.200 25.562 23.631 22.655August 26.142 25.609 23.507 22.724

. . . .

2006 June 26.202 25.454 23.662 22.607

July 26.199 25.523 23.591 22.667

August 26.135 25.637 23.466 22.697September 26.113 25.735 23.383 22.715

2007 June 26.214 25.464 23.674 22.568

July 26.227 25.535 23.619 22.582

23

September 26.152 25.829 23.313 22.629


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` Scatter Diagram of Predicted Data and

27

26

(THD)

25

eLevelabove

24

ObservedTi

23

22

22 23 24 25 26 27

Predicted Tide Level above (THD)

Correlation Coefficient = 0.965;

Regression Equation:Actual Level = 0.965 Predicted level + 0.90124


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Base Tidal Sine Curves for present day

po o un er re c e verage e eve s

HH, HL, LH, LLAdjusted using regression equation

150mm added to take account of storm surges

-

and Western Suburbs

Trombay Predicted Average Tide Levels HH, HL, LH, LL

Base curve to be used for City (North- East Catchments) and

Eastern Suburbs

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` Base Curves

26.155

27.0

25.721

.

24.0

25.0

26.0

HHHL HL

23.111

23.831

22.0

23.0

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

LH

LL

City (except north-east catchments) and Western Suburbs (Apollo Bunder data)28.0

26.737

. 26.737

26.0

27.0HH

HLHL

23.782

24.623

23.0

24.0

.

LH

LL

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

City (north-east catchments only) and Eastern Suburbs (Trombay data)26


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Long term Tidal Sine Curve

Base Curves were adjusted by adding

Long term rise in sea level of 225mm in 25

Long term rise in sea level of 900mm in 100

years

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` Long Term Tidal Curves for City (except

-28.0

25.946

26.380 25.946

26.0

27.0

HH

HL HL

23.33624.056

23.0

24.0

.

LHLL

Curve for deflection point after 25 years

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

28.0

26.621

.

26.621

26.0

27.0HH

HL HL

24.011 24.731

23.0

24.0

.

LL

LH

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

Curve for deflection point after 100 years28


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` Long Term Tidal Curves for City (north-east

26.557 26.062

27.0

HH.

24.0

25.0

.HLHL

23.107

23.948

22.0

23.0LL

LH

28.0Curve for deflection point after 25years

26.737

.

26.73726.0

27.0HH

HL

HL

23.78224.623

23.0

24.0

.

LL

LH

Curve for deflection point after 100years

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

29

d i f O i i l i d l


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Updating of Original Brimstowad Master Plan

Collection of details of Chronic flooding spotsa a o ec on

Geotechnical aspects at various locations

City drains conditions by CCTV survey and photography Condition assessment of Bench marks established in 1993

Nullah Surve to obtain latest information on Nullah Ali nments,

L-sections, Cross-sections Condition Assessment of Outfalls

Flying Survey using LiDAR instrument to obtain a digital terrain

model, contour maps (0.25m interval), digital photographs withtopographic information

Socio-economic aspects of flooding by conducting a 1000

samples study

Financial losses due to flooding on 26/27 July 200530

U d i f O i i l B i d M Pl


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Updating of Original Brimstowad Master Plan

o e ng conom c na ys s

be carried out using INFOWORKS software to identify

consideration of Economic Analysis, technically and

ratio will be evolved.

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References

1. Rainfall Analysis for the Design of Storm Sewers

in Bombay

S.D.Chawathe et. al., Journal Institute of Engineers, Volume 58,c o er, .

2. Water Supply and Waste Water Disposal

. . . .

3. Report of the Fact Finding Committee, on Mumbai FloodsGovernment of Maharashtra Publication,2006

4. Rainfall Intensities and 26/7 Floods in Mumbai

S.D.Chawathe, JIWWA, July-Sept. 2005

. ea eve c anges a ong e n an oas

A.S. Unnikrishnan, N.I.O, Dona Paula, Goa, 2006

CochinShriniwas K. et. al., continental shelf research, 26, (10), 11B 32


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Analysis of Rainfall Intensities and Tides for Storms Water Management in Mumbai