Inception Report
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PROJECT AREA AND ISSUES
2.1
Project Area
The project area, Sg. Setiu catchment of approximately 500 sq. km, forms part of the northern zone
of Setiu District. Sg. Setiu flows with total length of 48 km flows north-easterly direction and
subjected to intermittent tidal influences from the South China Sea (Figure 2-1).
Sg. Setiu begins at Kg. Penarik and passes through Kg. Padang, Bandar Sri Permaisuri, Kg.
Banggul before continuing flow towards the South China Sea. Flooding problems have frequently
occurred along the middle and lower river stretches during heavy storm events. The floodwaters
over spilled the banks, causing inundation in low-lying riverine settlements and agricultural areas
along the riverbanks.
2.1.1
Topography and River System
Sg. Setiu catchment comprises several tributaries primarily Sg. Ima Putih, Sg. Lirim, Sg. Tarum,
Sg. Panchur Merah and Sg. Guntung (Figure 2-2). The conditions of the existing river system
within the study area is shown in Plate 2-1. Most of the river system generally comprises of natural
channels where the runoff is collected through small streams, then flows to the main streams and
discharges into the rivers.
The upper most catchment area of the Sg. Setiu Catchment is characterised by a steep terrain,
with highest level at 1000m above mean see level. The middle reach where Bandar Sri Permaisuri
is located tends to be of milder slope which average elevation of 20-50m above mean see level.
The project area is flat at the downstream.
In terms of river flow, this can lead to problems of water level rise/overflow due to the abrupt
transition from rapid to sluggish flow. The problem is compounded by higher erodibility at the
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upstream catchment due to the steepness of catchment slopes that meet the smaller sediment
load carrying capacity of the gentler lower reaches.
2.1.2
Climate and Rainfall
The project area, situated in the eastern of the Peninsula, experiences a maritime tropical climate.
The principal features of which is high humidity, and uniform and comparatively high temperatures.
Mean maximum day temperatures are usually not more than 35C, while mean minimum night
temperatures inland fall only to 25C.
The project area experienced a convective type of rainfall. This type of rainfall usually occurs in
short duration but the intensity can be quite severe. The average annual rainfall depth in the project
area is about 3000 mm. Average monthly rainfall is varies from 100 to 700 mm. The wet seasons
span the transitional periods between the monsoons, from March to November. In addition to rains
associated with the monsoons, rains are also derived from convective storms that occur
occasionally throughout the year during late afternoons. The rainstorms, last for a short duration,
are isolated and usually of very high intensities.
2.1.3
Landuse and Landcover
Upstream of the catchment the study area consists mainly forest and agriculture land. Within the
middle catchment, most of the areas are occupied with paddy field and the kampong areas. The
most downstream area is swampy. Present major development areas for residential, commercial,
institutional are found within the vicinity of the Bandar Sri Permaisuri.
Due to the rapid development in these areas, significant increase of peak discharges was
experienced. Existing river and drains have been frequently overloaded by discharge from ongoing development area.
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Existing and likely future landuse scenarios will be intensively investigated by the Consultant during
the present study, with emphasis on imperviousness of various landuses. Figure 2-3 illustrates the
likely land use projected up to 2015 as recommended by Jabatan Perancang Bandar dan Desa
Negeri Terengganu.
2.2
Flood Issues
The areas prone to floods in the project area that have been identified to date are are Kg.
Guntung, Kg. Tasik, Kg. Besu, Kg. Chaluk, Kg. Gong Terap, Bukit Kemudu, Bandar Sri Permaisuri
and Kg. Nyatuh. Based on the previous flood events, the highest flood level recorded is 1.5m to
2.0m (Figure 2-4).
2.2.1
The Nature of Flooding
Two types of flooding phenomena are commonly recognised in the study area. The first type of
flooding is caused by floodwaters in river. As runoff discharges from the upper catchments
accumulate, the water overspills its banks and inundates the low lying areas. This type of flooding
normally occurs as a results of rarer and catchments wide storm events.
The second type of flooding is caused by runoff from local sub-catchments that has filled the local
drainage systems during heavy rains, but cannot be drained into the main drain/river channel. In
some instances, temporary flooding occurs due to localised rainfall and local drainage system
problems only. Floods in the area may tend to get much worse when main river waters overspill
and coincide with inundated water in the local drainage area and stay stagnant over prolonged
periods after the rain.
2.2.2
Waterways Flow Gradient
The gradient of the river varies along the alignment due to erosion and sedimentation processes.
Flows are stagnant in normal condition and sluggish towards the downstream end, as shown in
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Plate 2-2. Such flow behaviours have encouraged rapid water level increment even after a short
heavy rainfall. Thus areas especially within the lower catchment are susceptible to flood.
2.2.3
Sedimentation and Undergrowths
Other impact of such flow pattern is the siltation problem. Slow flow or almost dead flow leads to
higher siltation potential. Materials are readily deposited and accumulated within the river section.
To a large extent, the deposits are composed of fertile materials which encouraged grasses,
creepers etc. to grow. The rate of growth may be rapid and where no or little maintenance, the
plants may cover the sizeable stretch of the river (Plate 2-3 & 2-4).
2.2.4
Tidal Effect
The Sg. Setiu Headworks is close to the Bandar Sri Permaisuri. During high tide and coincide with
the high discharges from upstream of Sg. Setiu, the controlled gate will cause the water level arise
and cause the drainage system from the town cannot discharge to the river (Plate 2-5).
2.3
Overview of the Previous Study Reports
A comprehensive feasibility study for Ketara Phase 2 was carried out by Rural Development
Corporation and Kumarasivam, Tan and Ariffin in 1992. One of the components of the feasibility
study is to provide flood mitigation plan for Sg. Setiu. Subsequently, in year 2000, a detailed
designed of the project area, viz. ‘Detailed Design, Construction Supervision and Commissioning of
Drainage, Flood Mitigation, River Mouth Improvement and Associated Works for Sg. Setiu’, was
undertaken by Iktisas Ingenieurs in association Ranhill Bersekutu Sdn Bhd.
However, due to some circumstances, the project has only been completed up to the interim stage
by the consultants. Owing to the delay in implementing the above project, rapid development has
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taken place in the catchment areas. At present, the Government is looking for a longer term and
more sustainable flood mitigation solution for timely implementation and completion.
In the Iktisas Ingenieurs in association Ranhill Bersekutu Sdn Bhd study, besides flood mitigation
plan for Sg. Setiu, the Consultant has also carried out other exercise such as lagoon master plan,
resettlement plan, and environmental impact assessment.
The consultant has identified 10
potential structures for the flood mitigation plan which includes:
Bunding

Bund with Sg. Caluk Diversion

Bund with Sg. Caluk Diversion and new opening at Setiu Lagoon

Dam at Kg. Che Long

Bund and two small dam upstream

Dam at Kg. Alur Bongor

Broad Crested weir at Kg. Alur Bongot

Dams at Sg. Guntung

Barrage at Sg. Bari

Diversion of Sg. Guntung
Computer model, MIKE11 was used to predict the water levels reduction along the river for each of
the alternatives. From the MIKE11 result, it is shows that those alternatives did not work well and
some refinement need to be made. Then, the consultant has proposed 5 new elements to be
investigated and they are (Figure 2-5):
Bund from Kg. Buloh to Kg. Che Selamah

Penarik Break water

Sg. Merang Diversion

Barrage at Sg. Bari

Sg. Caluk Improvement
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To further analyze the new proposed flood mitigation plan, besides the additional 5 elements, the
consultant has also proposed several storage sites and some river improvement of Sg. Setiu to
included in the plan. Among the storages sites identified are at Upstream Sg. Setiu, Sg. Lirim and
Sg. Ima Putih (Figure 2-6).
Further analysis were carried out by the consultant for those alternatives, recommended alternative
are as fllows:
Construction of 3 dams – Upstream of Sg. Setiu, Sg., Lirim and Sg. Ima Putih

Construction of bund form Kg. Buloh to Kg. Che Selamah

Penarik Breakwater

Sg. Bari Barrage

Merang Diversion

Sg. Caluk Improvement
The findings on the suitability of the proposals given above will be analyzed and reviewed and shall
be presented in the next Conceptual Design Report.
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