analysis and design of an efficient drainage system in chittagong city

WELCOME TO OUR PRESENTATION

CHITTAGONG UNIVERSITY OF ENGINEERING & TECHNOLOGY

Project title : Analysis and design of an efficient drainage system in Chittagong city

(2 no. Gate to Dampara Bus Counter)

Performed by: Sabbir Ahmmed(0901058) Md. Ibrahim Khalil (0901038)

Supervised by : Dr. Md. Hazrat Ali Professor Department of Civil Engineering CUET

BACKGROUND Chittagong is the second largest city of

Bangladesh. As it is one of the largest port city of Bangladesh, it is very important to have a proper and modern drainage system for the maximum welfare and prosperity of the city.

It is also have a great attraction for tourism. Every years many tourists come to visit here. Poor drainage system is responsible for decreasing the beauty of city.

During the rainy season it is often over flooded all over the city and creates severe water logging.

Transportation system is very much affected for poor drainage system.

MAP OF STUDY AREA

Source: Google Earth

2 No. Gate

Dampara Bus counter

N

STATEMENT OF THE PROBLEMInefficient drainage system causes various

problems which are very harmful for human health and environment

The main problems are listed below:

Siltation in most drains. Vegetation in some drains. Various wastes obstruct the flow of drain. The covers of drain are not available in all

places.

OBJECTIVES To observe the existing condition of drainage

system of the road. To find out the problems which are responsible for

inefficient drainage system. To fix up the problems and find out the solution. To provide efficient drainage network system

• Data collection.• Prevent water logging • Properly dispose of storm water.• Prevent environmental pollution such as stopping

breeding of mosquitoes, odor and nuisance etc.• Improve hygiene condition of people.• Make a convenient way for pedestrian passing

nearby.

SCOPE

PRESENT DRAIN CONDITION

VEGETATION AND SILTATION

PRESENT DRAIN CONDITION

BLOCKAGE OF DRAIN

METHODOLOGYSelect the catchment areas

Collection of data

Design for the cross section of drain

Design the layout of drainage network

FORMULAS WE USED

Total discharge, Q = Runoff from rainfall + Domestic and Public use + Tidal effect

Runoff from rainfall , Q = CIA Q = runoff C = coefficient representing ratio of runoff to

rainfall I = intensity of rainfall A = drainage area

[M. Firoze Ahmed,2000]

The Manning equation is as follows:  Q = AV

Here ,V = (1/n)*R2/3 *S1/2

Where, V = Velocity A =Area of section of drain n = Manning co-efficient of channel

roughness R = Hydraulic radius, S = Longitudinal slope

[Van Te Chow,1959]

From the previous equation we assume a value of width of the drain and then we can get the depth of flow. We find the exact value of depth by trial and error method.

Free board, F = √(CY)Here, C = co efficient (1.5 for Q < 20cfs, 2.5 for Q > 20cfs) Y = Flow depth in feet

[Van Te Chow,1959]

COLLECTED DATA

[Chittagong Weather Office]

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0

100

200

300

400

500

600

700

800

5 12

59 68

240

589

687

538

285246

55

8

Mean monthly average rainfall for last 25 years

Month

rain

fall (

mm

)

DIFFERENT CATCHMENT AREAS

[Google Earth]

ESTIMATION OF DISCHARGE OF SEGMENTED AREASDesignation Area(m2) Run off

co-efficientC

Designation

DischargeQ=CIA (m3/s)

A1 218750 0.6 Q1 1.04

A2 154872.5 0.8 Q2 0.98

A3 262361.14 0.8 Q3 1.67

A4 1605860 0.6 Q4 7.66

A5 10850 0.4 Q5 0.03

A6 29947 0.6 Q6 0.14

A7 27772.88 0.3 Q7 0.07

A8 22569 0.8 Q8 0.14

A9 260408.33 0.8 Q9 1.66

A10 47741.74 0.7 Q10 1.45

A11 62493.75 0.4 Q11 0.2

Designation

Area(m2 )

Run offco-efficientC

Designation DischargeQ=CIA (m3/s)

A12 75516.85 0.8 Q12 0.48

A13 99823.19 0.8 Q13 0.63

A14 162754.17

0.8 Q14 1.04

A15 95483.65 0.8 Q15 0.61

A16 7811.75 0.8 Q16 0.02

A17 43401.39 0.3 Q17 0.28

A18 105030.36

0.8 Q18 0.67

A19 87887.812

0.8 Q19 0.56

A20 43401.39 0.4 Q20 0.14

A21 69876 0.8 Q21 0.44

A22 361967 0.8 Q22 2.3

A23 36457.17 0.3 Q23 0.09

NEW DRAINAGE LAYOUT

CROSS SECTION OF SOME DRAINS

1.25

1

1.25

1

Drain no

Width(ft)

Flow depth (ft)

Free board F=√(CY)

Total depth(ft)

1 2 2.66 2.52 5.18

2 3 3.57 2.98 6.55

3 4 3.93 3.13 7.06

4 3 3.54 2.92 6.51

5 2 1.54 1.94 3.48

6 7 4.62 3.39 8.01

7 4 3.08 2.77 5.85

8 2 2.03 2.25 4.28

9 8 5.11 3.57 8.68

NEW CROSS SECTION OF DRAIN

NEW CROSS SECTION OF DRAINDrain no Width

(ft)Flow depth (ft)

Free board F=√(CY)

Total depth(ft)

10 2 1.54 1.96 3.5

11 2 0.72 1.0 3.72

12 2 2.09 2.28 4.37

13 2 2.77 2.63 5.4

14 2 1.11 1.66 2.77

15 2 1.24 1.76 3.0

16 4 1.21 1.73 2.94

CONCLUSION In our project work, tidal effect does not

considered because the elevation in our study area is enough high from the maximum sea water rise in tide period.

In our design, we do not consider silting.

We designed the drainage network that whole discharge from high elevation point flows to the 2 no. gate as there is the lower elevation.

We connected our drainage network to 2 no. gate. Then it goes to Muradpur drainage network which ultimately dispose in Mirza khal.

RECOMMENDATION The drains should be cleaned as early as

possible which are filled with silt and blocked the drain.

We recommend to construct a silt trap at some critical point or where there is a possibility of overflow.

The drains are to be covered so that people can not throw various wastes into the drains.

Public awareness can be raised about cleanliness.

Proper maintenance should be taken.

THANK YOU ALL