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 MOHD HADZIR SX130614KAWS04 PUTRI NORSAFIAH BINTI AHMAD HAIRUDIN SX130619KAWS04 RAHSIDI SABRI BIN MUDA SX130622KAWS04
SESI - SEM
2013/2014 – 2 2
SECTION
02
LECTURER
DR. MOHAMAD HIDAYAT BIN JAMAL
ii
TABLE OF CONTENTS
CHAPTER
1
2
TITLE
PAGE
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
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
1.1
INTRODUCTION
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
Extensive Basin Flood Inundation Basin Flood Inland Flood Urban Flash Flood
Causes of Flooding
Riverbank Overflow Backwater effect from tidal influence affecting lower reaches Poor drainage from inland flood prone area 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 lowlying 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:
1.5
1.
To conduct hydraulic analysis to existing Sg. Pusu channel.
2.
Providing a solution to the flooding problem.
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
2.1
ANALYSIS AND RESULT
Existing Site Condition
The channel is combination of 2 types of channel as li sted 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
Channel 1 Channel 2
2.2
L (m) 280 200
Geometrical Properties y (m) B (m) z 2.75 2.5 4 3.2 6 0
S (%) 0.2 0.32
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
March No.
Works Description
Action by
1
Site Survey
Yusri/Rashidi
2
Survey Data Processing
Yusri/Rashidi
3
Plan Drawing
Nazirah
4
Calculation
Asyraf
5
Report Preparation
Putri
6
Submission
Week 5
Week 6
April Week 7
Week 8
APPENDIX 2 Site Plan
Week 9
May Week 10
Week 11
Week 12
Week 13
APPENDIX 2 Site Plan
UTM SPACE E S T D
APPENDIX 3 Calculation Sheet
1 9 9 3
TM
APPENDIX 3 Calculation Sheet
Project:
Calculate by:
Group Assignment Section:
Asyraf Date:
Sg. Pusu
Sheet. No:
9/5/2014
Reference
Calculation
1/3 Output
Determine the flow rate:
Equation 2.2
i
T K
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
Select Major system for Institutional building/complex Assumed 2 hours storm duration
Appendix 2.B Table 2.B1
d = 2
Select Station ID 3217001, Km 16 Gombak 66.328, K 0.144, 0.230, 0.859 i
Equation 2.3
ARI = 100years
d
Q
66.328 100
0.144
T K
2 0.23
0.859
64.64
i = 64.64mm/hr
CiA 360
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
Q
CiA 360
0.95 64.64 450 360
C = 0.95 A = 450ha.
77
Q 77 m3 s
Project:
Calculate by:
Group Assignment
Asyraf
Section:
Date:
Sg. Pusu
Sheet. No:
9/5/2014
Reference
Calculation
2/3 Output
Check Existing Channel
Channel 1 (trapezoidal grass channel):
Table 2.3
d
2.75 m
B
2.5m
z
4
n
0.035
L
280m 69.7
S
68.8
0.0032
280
AR
Q
2
3
S
n
5
3
2
2
2.5 2 y
5
1 4
3
2
2
By zy 2
Qn
S
P 3
2.5 y 4 y yo yc
A
B 2 y
77 0.035
0.0032
3
5
3
1 z 2
2
Qn
S
3
yo 2.74m
y 2.74m
subcritical
subcritical
yo d OK Channel 2 (rectangular concrete channel):
Table 2.3
d
B
n
L
3.2m 6m 0.015 200m 68.8
S
68.4
0.002
200
A
5
3
2
Qn
6 y
5
3
6 2 y
2
yo yc
5
3
B 2 y
S
P 3
By
77 0.015
2
S
3
0.002
3
Qn
yo 3.21m
y 3.21m
subcritical
subcritical
yo d OK
Check transition from channel 1 to channel 2: Eo y o
A 2T
yo
By zy 2 2 B 2 zy
2.5 2.74 2 2.74
2
2.74
2 2.74 4 4 2.74
3.49m
Eo 3.49m
Emin Eo h Eo 0 Eo 3.49m
yc 2 3Emin 3.49 2 3 2.33m qc
gyc3 9.81 2.333 11.12 m3 ms
Bc Q qc 77 11.12 6.93m B2 6m Bc
Bc 6m B2 control
Project:
Calculate by:
Group Assignment
Asyraf
Section:
Date:
Sg. Pusu
Sheet. No:
9/5/2014
Reference
Calculation
3/3 Output
q2 Q B2 77 6 12.83 m3 ms yc 2 2.56m
yc 3 q 2 g 3 12.832 9.81 2.56m Emin 1.5 yc 1.5 2.56 3.84m
Emin2 3.84m
y2 yc 2 2.56m
y2 2.56m
E1,3 Emin h Emin 0 Emin 3.84m
E1,3 3.84m
y3 y1
q2 2 gy3
A 2T
2
2
y3
y1
12.83
19.62 y3
2
3.84m
By1 zy12 2 B 2zy1
y1
y3 2.56m
2.5y1 4 y1
2
2 2.5 8 y1
y3 2.56m
3.84m
y1 3.02m d 1
y1 3.02m
overflow
Determine length of backwater: Calculated at 5 depth intervals
Q 2T 1 y gA3 x 2 S K 1 K
y S
3.02 2.74 5 0.0032
17.5
Q 2T
K Let 1 and 1 3 gA K
2
x 17.5 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
Proposed Channel
Proposed to increase top bank along channel 1.
16.3.3
Depth to be provided = 3.1 m
Proposed geometric:
Freeboard = 0.3 m
B
Proposed new depth = 3.4 m
y
Additional bank height = 3.4 – 2.75 = 0.65m
z
2.5m 3.4m 4
