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