SKAA 2513

HYDRAULICS

STUDY ON FLOOD PROBLEM AT SG. PUSU

STUDENT/

MATRIC NO.

MOHD YUSRI BIN MOHAMED YUNUS

SX130576KAWS04

MUHAMMAD ASYRAF BIN MASRI

SX130588KAWS04

NUR NAZIRAH BINTI MOHD HADZIR

SX130614KAWS04

PUTRI NORSAFIAH BINTI AHMAD HAIRUDIN

SX130619KAWS04

RAHSIDI SABRI BIN MUDA

SX130622KAWS04

SESI - SEM 2013/2014 2

SECTION 02

LECTURER DR. MOHAMAD HIDAYAT BIN JAMAL

ii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

1 INTRODUCTION 1

1.1 Background 1

1.2 Flooding and Drainage Issue 1

1.3 Problem Statement 2

1.4 Objectives of Study 3

1.5 Scopes of Study 3

2 ANALYSIS AND RESULT 4

2.1 Existing Site Condition 4

2.2 Analysis 4

2.3 Result 5

3 RECOMMENDATION 6

4 REFERENCES 7

APPENDICES

Appendix 1 - Work Program

Appendix 2 - Site Plan

Appendix 3 - Calculation Sheet

CHAPTER 1

1 INTRODUCTION

1.1 Background

The International Islamic University Malaysia (Universiti Islam

Antarabangsa Malaysia), also known as IIUM or UIAM, is one of the Public

Institutions of Higher Education (PIHE) in Malaysia. The main IIUM Campus is

nestled in a valley in the rustic district of Gombak, a suburb of the capital city of

Kuala Lumpur. This Garden of Knowledge and Virtue covers 700 acres, with elegant

Islamic-style buildings surrounded by green-forested limestone hills, attracts avid

photographers from among both locals and tourists.

1.2 Flooding and Drainage Issue

Flood is a nature and recurring event for a river and a stream. Flooding is a

result of heavy or continuous rainfall exceeding the absorptive capasity of soil and

the flow capacity of drainage, river or stream. This causes a water s to overflow onto

adjacent lands or river bank. In general, those land most subject to recurring floods,

situated adjacent to river and streams or drainage system is known as floodplains

area. Table 1.0 shown flood type and their causes.

2

Table 1.1: Flood type and their causes

Flood Type Causes of Flooding

Extensive Basin Flood Riverbank Overflow

Inundation Basin Flood Backwater effect from tidal influence affecting lower

reaches

Inland Flood Poor drainage from inland flood prone area

Urban Flash Flood Inadequate drainage and storage system to catyer for rapid

urbanization

Flash floods are caused by the combination of various factors, among others

including the failure of the system due to blocked and silted drainage, insufficient

drainage systems, high rainfall intensities and improper garbage disposal.

1.3 Problem Statement

There are several flood occurrences in the Project area that have been

recorded. However, severe flooding occurred in October 2010, April 2012 and the

recent one in October 2013 (Rekod by Development Department IIUM). Most of the

floods occurred during the inter monsoon period which brought high intensity

rainfall to the relatively small catchment areas. In general, flood occurring at the low-

lying areas could be aggravated by the insufficient capacity river, inadequate

capacity of drains and coupled with sediment loading in the river and drainage

system.

Floods occurred in many parts of the Project area and the frequent flooded

locations are listed below:

1. Low laying area within the vicinity of Kulliyah Architecture

2. Main Road from gate 1.

During the flood event in October 2013, the depth of flood water reached

almost 0.6m at those area. The recorded flood depth are between 0.3m 0.65 m

during heavy rainfall.

3

1.4 Objectives of Study

The main objectives of this study are as follows:

1. To conduct hydraulic analysis to existing Sg. Pusu channel.

2. Providing a solution to the flooding problem.

1.5 Scopes of Study

The study was focused on Sg. Pusu near the gate 1 of IIUM, which was the

location of the recent flood around the area. The scopes of study are:

1. Survey the site to collect existing hydraulic geometric proporties of

the channel.

2. To analyse the colected data to determine the cause of the problem.

3. To design the most optimum channel to solve the flooding problem.

The location of the study site is shown below.

Figure 1.1: Location of study site

CHAPTER 2

2 ANALYSIS AND RESULT

2.1 Existing Site Condition

The channel is combination of 2 types of channel as listed below:

1. Channel 1: Trapezoidal earth grass channel located upstream.

2. Channel 2: Rectangular concrete channel located downstream.

The site plan is attached in Appendix. The geometrical properties of the

channel are tabulated below

Table 2.1: Geometrical properties of existing channel.

Channel ID Geometrical Properties

L (m) y (m) B (m) z S (%)

Channel 1 280 2.75 2.5 4 0.2

Channel 2 200 3.2 6 0 0.32

2.2 Analysis

Analysis was made in accordance to MSMA 2nd Edition by JPS. The flow

rate was calculated using rational method and hydraulic anaylisis was made using

Manning equation. Calculation sheet is attached in Appendices.

5

2.3 Result

Exsiting geometrical properties for both channel is sufficient to receive the

calculated flow rate. However the transition between these two channels was proved

to be the cause of the flood problem.

The rectangular channel acted as a expansion for trapezoidal channel. Even

though the bottom width of rectangular channel is wider than trapezoidal channel, the

width is smaller compared to the critical width required by trapezoidal channel

resulting the backwater. Height of backwater is greater than the depth of trapezoidal

channel which caused the flood.

CHAPTER 3

3 RECOMMENDATION

The solution proposed to solved the problem is to embank the top bank of

trapezoidal channel to increase the depth up to the height of backwater. 300mm

freeboard has also been proposed as required by MSMA.

This is the most suitable solution and selected based on following

justifications:

1. The least cost and time for contruction

2. No interuption to existing channel

3. No channel protection or diversion required

4 REFERENCES

Amat Sairin Demun (2010). Lecture Module for SKAA 2513 Hydraulics.

Unpublished, UTM.

Department of Irrigation and Drainage Malaysia, JPS (2012). Urban Stormwater

Management Manual for Malaysia (MSMA 2nd Edition). Retrieved from

http://www.water.gov.my on January 22, 2013.

APPENDIX 1

Work Program

STUDY ON FLOOD PROBLEM AT SG. PUSU

Work Program

No. Works Description Action by

March April May

Week

5

Week

6

Week

7

Week

8

Week

9

Week

10

Week

11

Week

12

Week

13

1 Site Survey Yusri/Rashidi

2 Survey Data Processing Yusri/Rashidi

3 Plan Drawing Nazirah

4 Calculation Asyraf

5 Report Preparation Putri

6 Submission

APPENDIX 2

Site Plan

SPACEE S T D 1 9 9 3UTM TM

APPENDIX 3

Calculation Sheet

Project:

Group Assignment

Calculate by:

Asyraf

Section:

Sg. Pusu

Date:

9/5/2014

Sheet. No:

1/3

Reference Calculation Output

Equation 2.2

Determine the flow rate:

KTi

d

Where:

i = average rainfall intensity (mm/hr)

T = average recurrence interval, ARI (years)

d = storm duration (hours)

, , ,K = constants based on location

Table 1.1

Appendix 2.B

Table 2.B1

Select Major system for Institutional building/complex

Assumed 2 hours storm duration

Select Station ID 3217001, Km 16 Gombak

66.328, 0.144, 0.230, 0.859K

ARI = 100years

d = 2

0.144

0.859

66.328 10064.64

2 0.23

KTi

d

i = 64.64mm/hr

Equation 2.3 360

CiAQ

Where:

Q = flow rate (m3/s)

C = runoff coefficient

i = average rainfall intensity

A = catchment area (ha.)

Table 2.5 Select highest coefficient for major system

Measured catchment area

C = 0.95

A = 450ha.

0.95 64.64 450

77360 360

CiAQ

377Q m s

Project:

Group Assignment

Calculate by:

Asyraf

Section:

Sg. Pusu

Date:

9/5/2014

Sheet. No:

2/3

Reference Calculation Output

Table 2.3

Check Existing Channel

Channel 1 (trapezoidal grass channel):

2.75

2.5

4

0.035

280

69.7 68.80.0032

280

d m

B m

z

n

L m

S

552 2 3

3 3

2 23 32

52 3

232

2 1

2.5 4 77 0.0352.74

0.00322.5 2 1 4

By zyAR S A Qn QnQ

n S SP B y z

y yy m

y

subcriticalo cy y

2.74oy m

subcritical

oy d OK

Table 2.3

Channel 2 (rectangular concrete channel):

3.2

6

0.015

200

68.8 68.40.002

200

d m

B m

n

L m

S

5533

2 23 3

53

23

2

6 77 0.0153.21

0.0026 2

ByA Qn Qn

S SB yP

yy m

y

subcriticalo cy y

3.21oy m

subcritical

oy d OK

Check transition from channel 1 to channel 2:

22 2.5 2.74 2 2.742.74 3.49

2 2 2 2 2.74 4 4 2.74o o o

A By zyE y y m

T B zy

min 0 3.49o o oE E h E E m

min2 3 3.49 2 3 2.33cy E m

3 3 39.81 2.33 11.12c cq gy m ms

77 11.12 6.93c cB Q q m

2 6 cB m B

3.49oE m

6cB m

2 controlB

Project:

Group Assignment

Calculate by:

Asyraf

Section:

Sg. Pusu

Date:

9/5/2014

Sheet. No:

3/3

Reference Calculation Output

3

2 277 6 12.83q Q B m ms

2 23 3 12.83 9.81 2.56cy q g m 2 2.56cy m

min 1.5 1.5 2.56 3.84cE y m min 2 3.84E m

2 2 2.56cy y m 2 2.56y m

1,3 min min min0 3.84E E h E E m 1,3 3.84E m

2 2

3 3 32 2

3 3

12.833.84 2.56

2 19.62

qy y m y m

gy y 3 2.56y m

2 2

1 1 1 11 1 1 1

1 1

2.5 43.84 3.02

2 2 2 2 2.5 8

A By zy y yy y y m y m

T B zy y

1 13.02y m d

overflow

Determine length of backwater:

Calculated at 5 depth intervals

2

3

2

1

1

Q T

y gAx

S K

K

3.02 2.7417.5

5 0.0032

y

S

Let 2

31

Q T

gA and

2

1K

K

17.5x

y y T A R K x m

3.020

2.964 2.992 26.436 43.288 1.593 1687.047 0.803 0.352 39.935

2.908 2.936 25.988 41.820 1.566 1611.090 0.785 0.289 47.493

2.852 2.880 25.540 40.378 1.538 1537.293 0.766 0.219 61.037

2.796 2.824 25.092 38.960 1.511 1465.631 0.744 0.141 92.098

2.740 2.768 24.644 37.567 1.483 1396.078 0.719 0.054 234.799

Total Length 475.36

475.36 280

Backwater length channel length overflow the whole channel

16.3.3

Proposed Channel

Proposed to increase top bank along channel 1.

Depth to be provided = 3.1m

Freeboard = 0.3m

Proposed new depth = 3.4m

Additional bank height = 3.4 2.75 = 0.65m

Proposed

geometric:

2.5

3.4

4

B m

y m

z