23/1/2020 0 For Approval VK MTM DGP

DATE REV. NO. DESCRIPTION Designed Checked Approved

REVISIONS
EPC CONTRACTOR : PROOF CONSULTANT
LANCO-RITHWIK Joint Venture S. Ramakrishna & Consultants
Bangalore

CLIENT : SAFETY CONSULTANT

PWD (NH Division), Maharashtra DVR Techno Legal Consultants Kukatplly
(Ministry of Road Transport & Highway) Hyderabad
Bridge @ Chainage. 95+811

DESIGN CONSULTANT :

RRRK Associates Pvt Ltd Hyderabad

PROJECT : Rehabilitation & Upgradation of Sillod-Ajanta-Faradpur to 4 Lane in the state of Maharashrta

JOB No. O10000-C-RP

TOTAL NO. OF PAGES TITLE :
NAME SIGN DATE
DSGN VK 23/1/2020

CHKD MTM 23/1/2020

Hydrological Calculation of Minor Bridge at 95+811
APPD DGP 23/1/2020

CODE REV.
DOC. No. O 1 0 0 0 - C - R P - M N - H C - 0 0 0 4
IRC 0

RELEASED FOR PRELIMINARY TENDER INFORMATION P APPROVAL CONSTRUCTION

 Bridge @ Chainage. 95+811

PROPSED BRIDGE :-

1) Location @ : 95+811 Km

2) (a)-Span Details : x m
(b)- Width of the pier : m (top)
m (bottom)

3) Catchment area : 0.340 Sq.Km

4) Length of the Catchment : 0.70 Km

Distance from the C.G of

5) : 0.4 Km
Catchment to the end point

6) RL @ the starting point : 630.0 RL @ the end point : 591.0

Skew : 0

7) Bridge Deck Level :

8) Soffit Level :
`
9) Bed Level :

10) HFL : 370.274 (From local enquiries)

11) Bed Material : Medium sand Muram

12) Other Details : 1)- There is a defined catchment area

2)-
2)-

Condition of the stream : Good

PROPOSED STRUCTURE :- 1)- Superstructure : x m ( Slab girder )

2)- Substructure : Abutments
m wide RCC Pier
3)- Foundation :

95+811 chainage Minor Bridge

 Bridge @ Chainage. 95+811

3) Flood Discharge Calculations by Unit Hydrograph Method :

Simplified Approach :

Catchment area of the river, A = 0.3400 Km2

Total length of the stream, L = 0.70 Km

Length of the stream to the C.G = 0.40 Km

of the catchment, Lc

Slope, S = 55.71 m / Km

Design storm duration, Td = 0.6083 x ((L x Lc / √(S))0.405 )

= 0.1609 hr.
Say 0.20 hr.

50 years, 24Hr. point fall = 60.05 cm

Conversion factor for conversion

of the above rainfall to 0.2Hr.point = 0.40
fall

0.2 hr.point fall = ( 60.05 x 0.4 ) R50 = 24.02 cm

K50 x S0.176 x A x R50

Discharge, Q50 =
(L Lc)0.353
(K50 = 2.226 from FIG. B - 2)
= 57.8227 cumecs

Since there are many wells and ponds in the catchment area eating
up the discharge,so we are taking 50% of Q50 as the effective
discharge calculated by UH method.

Q50 = 28.91136 (approx)

 Bridge @ Chainage. 95+811

4) Flood Discharge Calculations by Unit Hydrograph Method :

Synthetic Method :
a)- Calculation of parameters :
Catchment area of the river, A 0.3400 Km2

Total length of the stream, L = 1 Km

Length of the stream to the C.G of = 0.4 Km

the catchment, Lc

Slope, S = 56 m / Km

Design storm duration, Td = 0.6083 x ((L x Lc / √(S))0.405 )

= 0.1609 hr.
Say 0.20 hr.

i) tp = 0.553 x ((L x Lc / √(S))0.405 ) = 0.146 hr.

Say = 0.200 hr.

ii) qp = 2.043 / tp0.872 = 8.313 cumecs/sq.m

iii) W 50 = 2.197 / qp1.067 = 0.229 hr.

iv) W 75 = 1.325 / qp1.088 = 0.132 hr.

v) W R50 = 0.799 / qp1.138 = 0.072 hr.

W F50 = 0.158
vi) W R75 = 0.536 / qp1.109 = 0.051 hr.
W F75 = 0.081
vii) TB = 5.083 x tp0.733 = 1.562 hrs.
Say = 2.000 hrs.

viii) Qp = qp x A = 2.827 cumecs

50% = 1.413
75% = 2.120

ix) Tm = tp + tr/2 = 0.700 hr.

 Bridge @ Chainage. 95+811
b)- Drawing of a Synthetic Unit Hydrograph :

Estimated parameters of unitgraph were plotted to scale on a graph paper.

The discharge ordinates (Qi) of the unitgraph at ti = tr = 1hr. interval were
summed up,i.e, Qiti = 357.0000 cumec/hr.as shown in the graph &
compared with the volume of 1cm Direct Run-off Depth over the catchment
with the formula, S Qiti = A x d/(ti x 0.36) ,
where, A= Catchment area = 0.340 km2
d= 1.00 cm depth
ti = tr (the unit duration) = 1.000 hr.

0.34 x 1.00
Hence, S Qiti = = 0.944
0.36 x 1.00

c)- Estimation of Design Storm Duration :

The design storm duration (TD) = 1.1 x tp = 0.220 hr.

0.200 hr.

d)- Estimation of Point Rainfall & Areal Rainfall :

Reduction of point rainfall for
= 19.15 x 0.08 = 1.417 cm
storm duration of 0.2 hrs

Reduction of point rainfall to Areal

= 1.42 x 0.32 = 0.453 cm
Rainfall

e)- Estimation of Loss Rate :

Design loss rate adopted = 0.300 cm/hr.

 Bridge @ Chainage. 95+811
f)- Time Distribution of Areal Rainfall :

Distribution 1hr. Rainfall

Duration in hrs. Storm Rainfall
Co-efficient (cm)
1 0.69 0.453446808510638
= 0.313
x 0.69 0.313
2 0.86 0.453446808510638
= 0.390
x 0.86 0.077
3 0.95 0.453446808510638
= 0.431
x 0.95 0.041
4 1.00 0.453446808510638
= 0.453
x1 0.023

g)- Time Distribution of Areal Rainfall :

1 hr. Rainfall Design Loss 1 hr. Effective

Duration in hrs.
(cm) (cm/hr.) Rainfall (cm)

1 0.31 0.300 0.01

2 0.08 0.300 0.00
3 0.04 0.300 0.00
4 0.02 0.300 0.00

h)- Estimation of Base Flow :

Total Base Flow = A x 0.045 = 0.0153 cumecs

i)- Estimation of 50-Yr. Flood (Peak only) :

Synthetic Graph 1hr. Effective Discharge

Time
Ordinate Rainfall (cm) (cumecs)

4 94.00 0.013 1.211

3 93.00 0.000 0.000
5 58.50 0.000 0.000
6 35.00 0.000 0.000
2 34.00 0.000
7 19.50 0.000
8 11.00 0.000
1 5.00 0.000
9 5.00 0.000
10 2.00 0.000
0 0.00 0.000
Total = 1.211
Base Flow = 0.0153
Total discharge,Q = 1.2259
 Hydraulic calculations for bridge

1 Discharge by Dicken's formula

As per I.R.C SP - 13, page - 7

1 Q = CM^0.75
C= 14 - 19 Where annual rainfall is more than 120cm
11 - 14 Where annual rainfall is 60 - 120cm
22.000 in western ghats
Value of C adopted in the present case 11.000
Catchment area (M) (Sq Km) = 0.340
Q (Cum/s) = 4.898

2 Discharge by Ryve's formula

as per I.R.C SP - 13, page - 7

Q = CM^(2/3)
C= 10.000
Catchment area (M) (Sq Km) = 0.340
Q (Cum/s) = 4.871

3 Discharge by Ingli's formula

as per I.R.C SP - 13, page - 7
Q = 125M / (M + 10)0.5
Q (Cum/s) = 0.340
Q (Cum/s) = 13.217
 Design Discharge & Linear Waterway Summary
S.No Method Discharge Calculated (Cumecs)

1 Synthetic Unit Hydrograph Method 1.23

2 Dicken's formula 4.90
3 Ryve's formula 4.87
4 Ingli's formula 13.22

1 Max Discharge 13.22

2 Min Discharge 1.23
3 Average Discharge 6.05
4 Median 4.88

Design Discharge (Average) 6.05

Linear waterways of Bridges

W = 8.60(Q50)1/3 16m
as per CWC sub-zone report 1(d) pg.no:90

Therfore a clear span of 16m is adopted

Clear Height is fixed based on the Highest flood level plus the free board from IRC 5

Therefore MNB Box size of 2 X 8 x7m is adopted