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CHAPTER 1
INTRODUCTION
1.1
Introduction
The city of Kuala Lumpur (KL) is located at the confluence of the Klang and the
Gombak Rivers. It was founded in the late 19th century as a settlement principally to
serve the tin miners that worked the riverside areas and the traders that attended to the
mining community’s needs. From this somewhat modest beginning, KL had grown over
the years, and is today Malaysia’s oldest and largest city rated also as one of Asia’s
richest capital.
The transformation of KL into an ultra modern metropolis has not been without
trials and challenges to the Government. As development took root and kept changing the
face of the city, existing infrastructures came regularly under pressure to service demands
that were way beyond their design limits. This called for repeated Government
intervention to upgrade and modernize affected facilities and keep the situation from
spiraling out of hand. In the history of the city, there have been numerous occasions when
government sponsored programs were implemented to improve the city’s services to be
in line with emerging demands.
One such facility that will be the subject of this thesis is the main drainage system
of KL for flood protection and drainage of the city. The phenomenal land use changes
taking place in and around the city during the last two decades have caused a total change
to the physical and hydrological character of the region, which in turn has subjected the
river system serving KL to be out of tune to deal with floodwater drainage.
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To counter the effect, Government has invested in a phased program to
rehabilitate and upgrade the existing drainage infrastructure. The early phases of this
program that began in the eighties, utilized a traditional approach that involved channel
improvement works to speed up the flow of the flood wave through the city and the
construction of upstream storage facilities to regulate down the magnitude of floodwaters
flowing into the city.
There is however, a limit to the application of such solutions and it became quite
apparent in the late nineties, when this limit was being reached. A completely new
approach for flood control was deemed necessary for KL. Since a few years back,
flooding problem in the Kuala Lumpur city centre has worsened as a result of rapid
development in the catchment areas, obstruction in waterway flow and limited space
available for river improvement works.
Therefore, the establishment of an accurate Flood Forecasting System in the
Klang River Basin is an important and effective non-structural measure to complement
the structural flood mitigation works. It will not only reduce flood damages due to
unexpected flooding of properties and provide warning against traffic disruption but also
will over time result in a better understanding of flooding in the basin. It is operational
since 2002; evaluation and re-calibration should be carried out from time to time to make
sure the accuracy of the MIKE 11 Modeling System with FLOOD WATCH as the
decision support system.
1.2
Statement of Problem
The forecasting component consists of data acquisition in real-time (Telemetric
System) and the flood forecast modeling system (MIKE 11 Flood Forecasting Module).
If one of these components failed to operate, the Flood Forecasting will not provide any
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results. This has happened before when failure in the Telemetric System cause MIKE 11
to give erroneous results
When setting up the modeling, all the parameters such as cross-section,
hydrodynamic, rainfall runoff, boundary data, time series and network setup must be
matched with the simulation file. If any one of these parameters do not match with the
simulation file, it will not generate any discharge and water level result that we needed.
1.3 Study Area
The Klang River Basin is located on the west coast of Peninsular Malaysia and
encompasses the Federal Territory of Kuala Lumpur and parts of the State of Selangor.
The study area is generally hot and wet throughout the year without much variation.
Nevertheless, the climate can be loosely defined by the following seasons:
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The north-east monsoon from December to March
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A transitional period from April to May
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The south-west monsoon from June to September; and
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A transitional period from October to November
It is also characterized by uniform high temperature, high relative humidity,
heavy rainfall and little wind. The average annual rainfall depth in the study area is about
2,400 mm. The highest rainfall occurs in the months of April and November with a mean
of 280 mm. The lowest rainfall occurs in the month of June with a mean of 115 mm. The
wet seasons occur in the transitional periods between the monsoons, from March to April
and from October to November.
In addition to rain associated with the monsoons, rainstorms derived from
convection occur occasionally throughout the year during late afternoons. The rainstorms
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last for a short duration, are isolated and usually of very high intensities. The temperature
throughout the year is quite constant with a mean of 27ºC. The highest temperature
increased at 1pm with an average of 32ºC and the lowest temperature decreased at 7am
with an average of 23ºC. As the relative humidity is very closely related to the
surrounding temperature, its variation throughout the year is also with minimum an
average value of 82%. The evaporation depth for open water is measured to be around
1500 mm per annum or monthly mean of around 125mm/month.
The study area is the most densely populated area in the country with an estimated
population of over 3.7 million (about 18 percent of the national population) and growing
at almost 5 percent per year. The Basin has an annual growth rate of approximately 5%
and land use is dominated by urban residential development (44%), followed by forest
reserves (34%), agriculture (15%) and commercial/industry (7%).
Urbanization and industrialization in the river basin has been rapid with major
portions of agricultural and ex-mining land being converted. As a result of the extensive
and rapid urban development in the basin area, problems emerged in the form of river
over bank floods; flash floods that afflict clogged drainage systems and river environment
degeneration. This prompted the commissioning of a number of flood mitigation and
river environment enhancement programs as the problems and the associated social and
economic costs were escalating with more urbanization.
The Klang River Basin has an area of about 1288 sq km, which encompasses the
Federal Territory of Kuala Lumpur, parts of Hulu Langat, Kuala Langat, Gombak,
Sepang, Petaling and Klang districts in Selangor State. The municipalities that fall within
the Basin boundaries include Petaling Jaya, Subang Jaya, Klang, Kajang, Shah Alam,
Selayang and Ampang Jaya.
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Figure 1.3.1: General Location Plan of Klang River Basin.
Figure 1.3.2: Local Authorities Within Klang River Basin.
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The Klang River originates from the Main Range about 25 km Northeast of Kuala
Lumpur at an altitude of about 1330 m. As is typical of rivers on the west side of the
Main Range, the river valley falls westerly to eventually meet the sea at the Straits of
Malacca. It flows through the most densely populated region in Malaysia, including the
capital city of Kuala Lumpur. The Klang River system is fed by 11 main tributaries
comprising a number of tributaries of which the Gombak, Batu, Ampang, Kerayong,
Kuyoh, Bunus and Damansara are major tributaries. The main Klang River has a length
of about 120 km. The upper basin above the existing dams (Klang Gates Dams and Batu
Dams) is mountainous with fairly steep slopes and still covered by tropical jungle.
1.4
Study Objective
This study is to review the flood mitigating measures implemented through the
SMART Project. It also simulate the Flood Forecasting in Klang River Basin in order to
compare the existing river system in Klang River Basin with and without the Stormwater
Management and Road Tunnel (SMART) which is now in the process of construction in
the city center of Kuala Lumpur.
For this study, the objective is to add-in the SMART alignment in the network
setup in the Flood Forecasting System for Klang River Basin by one of the component of
MIKE 11 Modeling System that is MIKE ZERO as the decision support system to
analyze the effects of SMART to the flood flow in Klang River Basin.
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1.5
Study Outline
Basically, the forecasting component consists of two main parts: data acquisition
in real-time (telemetric system) and the flood forecast modeling system (MIKE 11 Flood
Forecasting Module). In between these two components, the FLOOD WATCH decision
support system is installed to manage and assist the Flood Forecasting System operator to
collect the data for the forecast, generate the forecast and issue the bulletin/report. In
addition, FLOOD WATCH provides important tools for better assessment and overview
of the river system condition at the Time of forecast (ToF).
MIKE 11 Modeling System – to perform the calculation required to predict the variations
in discharge and water level in the river system as a result of catchments rainfall and
inflow/outflow through boundaries in the river system. The MIKE 11 Flood Forecasting
(FF) model is based on the Rainfall-Runoff (RR) and Hydrodynamic (HD) model of the
Klang River Basin, developed and calibrated under the flood mitigation component. It is
the automatic real time updating routine to minimize the deviations between observed
and simulated discharge and water levels at the time of forecast.
FLOOD WATCH - is a decision support system combining an advanced time series
database with the MIKE 11 modeling system and the Geographical Information System
ArcView. FLOOD WATCH was selected as the core to run the flood forecasting system.
It includes all activities involved in the preparation of a forecast: Management of input
data, processing of data, modeling and output of the forecast.
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Figure 1.5.1: Outline of the FLOOD WATCH System for Klang River Basin.
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Table 1.5.1 Procedures of Study
Procedures of Study
Input –
1. Data input from outsource
2. Boundary Estimates - Quantitative Precipitation Forecast (QPF)
Processing –
1. Quality Checking and Processing of Data
2. Data Conversion to MIKE 11
Modeling –
1. Network setup, Cross-section setup, Boundary data setup,
Hydrodynamic input, Simulation parameters input.
2. Model Simulation - Simulates a 3 Hours Forecast
3. Transfer of Model Results to the FLOOD WATCH Database
Output –
1. Forecast Bulletin/Report
2. GIS Display of Data
Conclusion –
1. Summary and Recommendation