Table of Contents
Introduction
Proposed Integrated Development Plans
Shoreline Management Plan
Acknowledgements

2.   BASELINE ENVIRONMENTAL CONDITIONS

The SMP documents the existing physical, ecological and socio-economic environment along the West Coast of Sabah as per early 1998. These data, supported by advanced numerical models of tide, wave, sediment and water quality processes, form the basis for the decision-making process within the study.

2.1 Regional Tidal Processes
The tidal regime along the North West Coast of Borneo is a mixed diurnal/semidiurnal type, implying that there may be either one or two high waters per days. Generally speaking, spring tides tend to show diurnal nature while neap tides appear semidiurnal. The maximum range is 2.4m and the mean tidal range is 1.3m. Tidal planes for Kota Kinabalu are given in Table 2.1.

    Table 2.1    Tidal planes for Kota Kinabalu

The tidal waves propagate primarily in an onshore-offshore direction along the coast, due in a large degree to the presence of the 3km deep Palawan Trench lying offshore as shown in Fig. 2.1. The dominantly onshore-offshore tidal regime implies that tidally-generated shore parallel currents on the regional scale are small, generally less than 10cm/s. Exceptions occur in areas which hinder the on-offshore exchange of water, such as the series of shoals lying some 40km offshore of Sabah (Vernon Bank, Saracen Bank, Sunken Barrier Shoals, etc.) and most notably in the constricted entrance channels to Brunei Bay.

Figure 2.1 Regional Bathymetry - 81KB

The ebb tide runs north and the flood tide runs south. Both the ebb and flood currents show a distinct cross-shore flow.

During the NE monsoon, the south going regional current dominates the tidal currents signal. This has tremendous importance for the transport of 'pollutants' emanating from the rivers north of the Klias Peninsula and is the major contributing factor to the occurrence of Red Tide in Kimanis Bay.

During the SW monsoon, the regional current runs northward along the Sabah coastline, again dominating the tidal current signal.

In principle, the SW monsoon reverses the trends of the NE monsoon on the open coast. Figure 2.2, in particular, illustrates the importance of the net flows where there is a clear flow path from Sg. Putatan to Pulau Manukan and the islands of the Tunku Abdul Rahman Marine Park. This means, and is supported by field observations, that all the suspended matter and debris from Sg. Putatan has a direct impact upon the waters of the Park during the SW monsoon after heavy rainfall. This is a clear threat to the important coral reserves in this area and action is required to reduce the suspended load and floatables in Sg. Putatan if the marine resources of Tunku Abdul Rahman Marine Park are to be maintained.

Figure 2.2    Typical SW monsoon current field in the Kota Kinabalu area - 46KB

2.2 Wind
The weather patterns over the entire Southeast Asia region are, to a large degree, governed by pressure systems developed over the large landmasses of the Asian and Australian continents. These drive monsoon winds that prevail over the region throughout long periods of the year and which are reflected in the wave climate, the surface currents and variations in the mean sea level due to the very large-scale wind set up.

2.2.1 Offshore Winds
Figure 2.3 shows the monthly wind roses offshore the West Coast of Sabah for the period June 1993 - July 1997. The NE-monsoon is at its peak in January, February and March before it tapers off in April and changes to southwesterly winds in May and June. The SW-monsoon peaks in July, August and September, tapers off in October, and changes to northeasterly winds in November and December.

Figure 2.3    Monthly offshore wind roses off the West Coast of Sabah. Based on data from June 1993 - July 1997 - 54KB

2.2.2 Nearshore Winds
The large landmass of Borneo changes the wind patterns over land and in the nearshore areas significantly. Figure 2.4 shows a wind rose for 1996 from the Kota Kinabalu (KK) Airport. The winds from KK are much weaker and the main directions are turned around 90° compared to the offshore winds.

Figure 2.4    Hourly mean wind rose for 1996 from Kota Kinabalu International Airport - 19KB

2.2.3 Typhoons
Sabah lies south of the main area influenced by typhoons, and major typhoon related storms are rare. This is the reason that Sabah is called "The Land Below The Wind." They do, however, occur on rare occasions, as illustrated by Typhoon Greg that caused havoc in December 1996. Typhoon Greg was an extreme event, and there are too few registered events to perform a detailed statistical analysis.

2.3 Waves
The West Coast of Sabah is exposed to waves from the South China Sea. Due to the string of offshore coral reefs, shoals and small islands, a large proportion of the wave energy in deep water is lost before reaching the nearshore area. Furthermore, the main wave directions offshore are basically parallel to the prevailing direction of the shoreline of the Sabah West Coast, such that the energy reaching the nearshore area is further reduced through large-scale refraction.

2.3.1 Offshore Waves
The offshore waves are primarily generated by the monsoon winds with some component of swell waves. Figure 2.5 shows that the directional distribution of the offshore waves is largely similar to the distribution of the offshore winds.

2.3.2 Nearshore Waves
Figure 2.5 shows that a significant reduction in wave height occurs as the offshore waves are transformed onshore due to the offshore reefs, sheltering by landmasses and large-scale refraction.

Figure 2.5    Offshore and Nearshore Wave Conditions - 212KB

2.4 River Flows and Sediment Loads
Rivers are of central importance to the shoreline management plan, as rivers are the primary transport mechanism for suspended sediment, pollution and nutrients to enter the nearshore marine environment. Much of the study area has been subjected to large-scale land use changes in recent decades. Examples of such land use changes are the clear-cutting of primary growth forest areas for timber, the clearing of jungle for agricultural and industrial areas, or the clearing of jungle and agricultural land for urbanisation.

It is clear that these land use changes have resulted in a net increase in soil erosion and a corresponding increase in suspended sediment concentration and nutrients in the rivers of the region. The effect is worsened when land clearing is performed by burning, as the remaining ash is high in nutrients and will be washed into the rivers. The additional river sediment and nutrient load is in turn transferred to the nearshore marine environment, resulting in higher turbidity levels and higher sedimentation rates there. Higher turbidity and sedimentation add environmental stress to corals and other marine organisms in the areas influenced by the river plumes. Land clearing within the various river catchments has, thus, clearly contributed to the deterioration of the nearshore marine environment.

Only a small amount of data is available describing the suspended sediment concentrations found in the rivers of Western Sabah. The available data indicates that the suspended concentrations vary from as little as 2.0mg/l to as much as 552mg/l, while that simultaneously discharge also typically vary over at least 2 orders of magnitude.

Figure 2.7 indicates the main sources of suspended sediments to the coastal zone.

2.5 Coastal Sediment Transport

2.5.1 Littoral Sediment Transport
The two main driving forces for shoreline sediment transport are waves and currents.

Figure 2.6 presents the calculated net sediment transport rates for 9 representative profiles. The dominant drift direction is towards the SW, although locally north-easterly drift occurs, for example immediately north of Sg. Papar and Sg. Tuaran. The drift rates are moderate. However, as the active profile is shallow, interference with even these moderate drift rates can and has led to significant coastline response.

Figure 2.6    Net littoral sediment transport rates along the West Coast of Sabah - 228KB

2.5.2 Marine Sediment Transport
The fine material emanating from the rivers enters the coastal system and is predominantly maintained in suspension by wave and current action due to its low settling velocity and is then transported along the coast and offshore by the prevailing tides and ocean currents. The material eventually deposits out some distance from the river mouths in zones sheltered from wave activity or in deeper water, where the wave action on the bed is mild.

Figure 2.7 presents the mean suspended sediment concentrations in the nearshore zone during periods with no net current, NE and SW monsoon seasons respectively.

The dynamics of the processes are clear. During the pure tide situation, which persists for about 40% of the year, there is little longshore movement of fine sediments. The major sources are clearly Sg. Tuaran, Sg. Papar and Sg. Padas, which even during pure tide situations has a plume extending some 15km into Brunei Bay.

During the NE monsoon, the sediments are swept southward along the coastline with large areas of Kimanis Bay being effected by material originating from Sg. Papar. During the NE monsoon, the coastline around Sipitang in Brunei Bay is particularly badly effected by sediments originating from Sg. Padas.

During the SW monsoon, the transport reverses and the area between Papar and Kota Kinabalu suffers highly suspended sediment loads. Kimanis Bay is relatively free of suspended sediments whilst Teluk Ambong, Teluk Usukan and Teluk Sulaman are impacted from sediments originating from Sg. Tuaran.
   
Figure 2.7        Mean concentration of suspended sediments over 7 days. Pure tide, NE Monsoon and SW   Monsoon. Main rivers are indicated with other features of interest - 76KB

2.6 Coastal Erosion
Coastal erosion is not a serious issue along the West Coast of Sabah due to the predominantly mild wave climate. A total of 19km of coastline has been identified as suffering some degree of erosion, of which only 4.5km can be presently classified as serious erosion (Fig 2.8). The SMP specifies erosion control strategies for all open coastal reaches suffering moderate or severe erosion. For example, the area suffering the most serious erosion is south of the Timberwell Jetty in Kimanis, where the peak erosion rate has been found to be as high as 15m/year. As the effected area does not represent an area of significant ecological or commercial importance, it is recommended that a 'do nothing' strategy is adopted for this area, with the area thus being defined as a sacrificial erosion buffer in the SMP.
  
Figure 2.8    Areas suffering coastal erosion - 19KB

2.7 Marine habitats
Mangroves dominate the south side of the Klias peninsula around the estuaries of Sg Klias and Sg Padas, of which a major part is gazetted as mangrove forest reserve. Mangrove forests also fringe Teluk Ambong and Teluk Usukan, and the large tidal lagoons of Teluk Sulaman, Teluk Mengkabong, Teluk Salut and Lake Sitompok. Narrow strips of mangroves line most of the river mouths in the study area.

Tracts of mangrove in Teluk Salut and Teluk Mengkabong are under severe pressure from the construction activity associated with the Kota Kinabalu Industrial park and a concerted management effort is required to avoid a critical loading situation upon this important habitat and fisheries resource. This is now the subject of on-going research by Danish Hydraulic Institute.

Soft-bottom seabed communities predominate the marine environment, accounting for about 90% of the open coastline in the study area. The soft-bottom macrozoobenthos serve as a food source for the demersal fish, and therefore represent an important fisheries resource. However, their abundant distribution is such that stress or destruction from marine reclamation works, although locally significant, is not of importance to the survival or diversity of the habitat as a whole.

Coral reefs are abundant and healthy along the shores of Teluk Usukan and Teluk Ambong. Further south around the headland of Tg. Gaya, Sapangar Bay, the Gaya straits and the islands of the Tunku Abdul Rahman Marine Park there are numerous coral reefs, all of which to one degree or another show signs of stress. The reef flats along the coast off Tg. Dumpil are also severely stressed (live coral coverage less than 10%) due to destructive fishing methods and the proximity of major sources of sediment loading. In contrast, the reefs surrounding the nearshore islands of Pulau Dinawan and Pulau Mantakud are in good condition and represent an important marine habitat and tourism resource.

2.8 Water Quality
A combination of the pollution load from land and the dilution effects of the South China Sea determine the water quality along the West Coast of Sabah. The spatial distribution of the various pollutants depends also on the prevailing tide, wind and ocean current conditions and therefore varies widely through the year.

The Ambong area in the north has the highest water quality along the West Coast, with water almost free of pollution for much of the year. The water quality around Kuala Penyu and Klias is generally also very good.

Most other coastal areas suffer from some degree of pollution or high turbidity. Coliform bacteria levels are higher than acceptable limits in some areas, for example, where Sg. Tuaran reaches the coast. Likas Bay faces similarly high bacterial pollution, due to the loading from Sg. Inanam, coupled with the poor water exchange into the bay. In Kinarut, high turbidity and bacterial pollution from river sources have led to severe degradation of the nearshore coral habitats.

Eutrophication can also occur when high nutrient loads trigger algal blooms. Blooms of red tides occur in Kimanis Bay, where cases of DSP (Diarrhoeic Shellfish Poisoning) and PSP (Paralytic Shellfish Poisoning) have been reported.

Pollution by the way of floating debris (e.g. plastic bags) is also a more obvious problem. Sapangar Bay for example is heavily affected by floating debris, and an estimated 7% of the bed is covered by non-degradable rubbish. The issue of floatables requires urgent intervention if the marine environment is to be viewed as attractive for international tourists.

2.9 Socio-economy
Though most of the coastal villages were once significant fishing communities, fishing today can be considered a relic of past heritage. Most of the villages have few full-time fishermen, such that subsistence has to be supplemented with a secondary economic activity. The same applies to the farmers, who also have to depend on other means to make a living.

Unemployment is a concern for all villages. In most cases, the development of resorts would be beneficial in terms of job creation for local unskilled workers, while the management and middle level staff would most probably be drawn from elsewhere.

Villagers are not adverse to the present tourism development that they witness in their areas. Some villages, nonetheless, are more exposed to tourism than others. A clear case is Tuaran, which has seen the establishment of several beach resorts in the past few years. Because of its close contact to the fast development of hotels, some villages in the area are showing signs of ambiguity to such development. Concerns centre mainly upon the perceived infringement of tourists to the villagers' daily life.  The SMP documents the existing physical, ecological and socio-economic environment along the West Coast of Sabah as per early 1998. These data, supported by advanced numerical models of tide, wave, sediment and water quality processes, form the basis for the decision-making process within the study.