7  WATER RESOURCES

7.1  Introduction

Sabah has been experiencing a surge in economic development in the last decade with more and more land use changes. Development in the coastal zone has been particularly rapid in the last several years. As the coastal areas are being developed, migration into the coastal areas from the rural areas and from the neighbouring countries has also increased with more and more of these people squatter on the coastline. These, coupled with the rapid increase in population have greatly affected not only the quantity of water supply but also the quality of the water supply throughout the State. Although Sabah has plenty of water supply sources, much of the water are not suitable or too remote to be distributed to the end users. Faced with this challenge, the Water Resource Master Plan for Sabah⁶³ was prepared to provide for an integrated approach to water resource management.

Fresh water supply sources in Sabah come from surface water and groundwater.

Figure 25: Water Resource in the Data Dictionary

The Water Resource for the Coastal Profile is grouped into three main categories to include surface water, groundwater and marine or estuarine water. For surface water description, it is necessary to include the sources and the amount of discharge from these sources. Flood prone areas and catchment areas are included because these are important in presenting the full picture of the availability of surface water in the coastal zone. Rainfall description is not presented in any of the three categories as this has been addressed in separate chapter. Water quality was considered important to include as this determines the level of management required and therefore was included in all three categories. Description of the groundwater is grouped into storage that includes the quantities and recharge and water use. The description of Marine water includes hydraulic, water quality. Extreme events are also included for management planning.

7.3  Surface Water

Surface water is one of the major sources of freshwater supply in Sabah. Surface water sources are from streams and rivers that flow into lakes, wetlands, watersheds and man-made reservoirs. The supply of surface water is renewable as long as there is enough precipitation. In Sabah, much of the surface water supply comes from major rivers. These rivers and their locations are shown in Figure 26.

7.3.1  Rivers

River Basins

Based on the information gathered from Figure 27, there are 19 river basins in Sabah. Of these, the Kinabatangan river basin on the East Coast is the largest basin covering an area of 15,385 km². The Padas River on the West Coast covers an area of 8,726 km². Most of the other basins cover smaller areas.

Rivers are the primary transport mechanism for suspended sediment, pollution and nutrients to enter the catchment areas. The significance of a given river with respect to sediment, nutrient or pollution loading depends upon both the discharge of the river and the concentrations of the various materials contained in the river water. Both these require long-term field data to be determined reliably.

River discharges can be measured directly using river gauging or current meters, or the discharge can be estimated from analyses of the river catchment. Source of data for river discharge on the west coast of Sabah are:

• DID’s river gauging network - daily mean flows for rivers, with either 1 or 5 years of data coverage. A major drawback of this data is the fact that the gauging stations are in some instances fairly far upriver and as such the measured discharge does not include the effect of the entire catchment and will thus be smaller than the discharge actually reaching the river mouth.
• Estimates via catchment analyses
• DOE - discharge via river gauging taken simultaneously with their sampling for river water quality. This data coverage is extremely sparse.
• SFI EIA Report - River discharges estimates are presented for several rivers in Brunei Bay in the EIA report from the Sabah Forest Industries pulp mill near Sipitang.

Figure 28 shows the river discharges, as provided by DID from their network of river gauging stations.

The largest rivers in terms of discharge are the Kinabatangan River, Padas River and Papar River. Data on river discharges is quite good for those rivers covered by the DID gauging stations; for others very little information is available.

According to the Water Resource Master Plan, there were 50 stream gauging stations operated by the DID. Of these, 21 stations have been discontinued. Of the 29 remaining stations in operation, 23 stations have fully automatic gauges and 3 stations with both automatic and staff gauges. Four staff gauges are only used for flood warning. Raw data prior to 1993 for all the gauges remaining in operation were not supplied for this chapter but description and interpretation of the data were presented in the Water Resource Master Plan.

Figure 26: Major Rivers in Sabah

Figure 27: River Basins in Sabah

Figure 28: DID River Gauging Stations (Map is currently unavailable)

Discharge data for 10 river stations operated by DID were made available for the year 1993-1997. Of the 10 river stations for which the discharge data were supplied, only four stations have data for five consecutive years from 1993-1997. The other six river stations only have discharge data for the year 1997. All the discharge stations for which the data were available are concentrated on the West Coast except for the Kinabatangan River, which is located on the East Coast. The monthly average, minimum and maximum discharge for these rivers are shown in Table 41, Table 42, Table 43, Table 44 , Table 45 and Table 46. Figure 29 shows the average of monthly mean discharge of the 4 rivers (1993 – 1997) and Figure 30 shows the average of monthly mean discharge of the 6 rivers (1997).

Figure 31 shows the minimum discharge for 4 rivers of which data were obtained for 5 years and Figure 32 shows the minimum discharge for 6 rivers of which data were only obtained for the year 1997. Previous year data dating back to 1965 are also available for several rivers and presented in figures in the Water Resource Master Plan.

Similarly, data for maximum discharge are also spurious and incomplete. Figure 33 shows the maximum discharge for 4 rivers that have data for continuous 5 years from 1993 to 1997. Figure 34 shows the maximum discharge for 6 rivers of which data were only available for the year 1997.

Table 41: Monthly Average of Daily Mean Discharge (CUMECS) for 4 DID River Gauging Stations for 1993-97

Table 42: Monthly Minimum of Daily Discharge (CUMECS) for 4 DID River Gauging Stations for 1993-97

Table 43: Monthly Maximum of Daily Discharge (CUMECS) for 4 DID River Gauging Stations for 1993-97

Table 44: Monthly Average of Daily Mean Discharge (CUMECS) for 6 DID River Gauging Stations for 1997

Table 45: Monthly Minimum of Daily Discharge (CUMECS) for 6 DID River Gauging Stations for 1997

Table 46: Monthly Maximum of Daily Discharge (CUMECS) for 6 DID River Gauging Stations for 1997

Figure 29: Average of Mean Monthly Discharge (CUMECS) of 4 Rivers, 1993 – 1997

Figure 31: Minimum Discharge (CUMECS) of 4 Rivers, 1993 - 1997

Figure 32: Minimum Discharge (CUMECS) of 6 Rivers, 1997

Figure 33: Maximum Discharge (CUMECS) of 4 Rivers, 1993 – 1997

Surface Water Quality

Surface water can be classified as either flowing water such as rivers and streams, or standing water such as lakes and ponds. The two systems differ in their ecosystem structure and in their water pollution problems. Water quality indicators in both flowing and standing water are the concentration of Dissolved oxygen (DO), the Biological Oxygen Demand (BOD) and the faecal coliform bacteria count. Water is considered polluted if the water system is overloaded with oxygen demanding wastes and when the bacterial activities causes the reduction of DO content to a level low enough to kill some species of aquatic organisms. When the BOD causes the DO level to fall below 4 ppm, the water is seriously polluted. Flowing water if not overloaded can dilute many waste and renew its supply of DO fairly rapidly. Standing water on the other hand, because of its low flow rates, may take years to flush out their contaminants.

Several government agencies in Sabah collect and monitor water quality for different purposes. These agencies include the DOE, Health Department, Water Department, JKR and DID. Summary statistics for rivers water quality data can be seen in the Water Resource Master Plan for Sabah Vol. 1.

Surface water quality in Sabah is adversely affected by various pollutants that enter the water bodies. Many of the open water bodies such as rivers and streams are heavily polluted either by agricultural wastes, farm wastes or human wastes as well as soils from erosion and surface runoff. The major pollutants found in surface water is the excessive amount of suspended solids particularly in river basins close to developments, agricultural estates and forestry activities. This increase in sedimentation has not only caused the increase in the cost of treatment of the water but also has reduced the availability of water that can be used for water supply. Report in the Water Resources Master Plan Negeri Sabah listed seven major pollutants found in Sabah's Waterways⁶⁴. These are presented in Table 47. Surface water pollutants are divided into physical, chemical, biological and pesticides/organic.

Physical pollutants that are commonly found in Sabah's waterways are sediments such as soil, silts and other solids from land erosion, plastics and other solid wastes. Sediment pollution come from either natural erosion, poor soil conservation, runoff from agricultural, mining, forestry and construction activities. These pollutants fill waterways, reservoirs and reduces the ability of water to assimilate oxygen demanding wastes. High turbidity have been particularly a problem for Sg. Tuaran, Sg. Padas, Sg. Kinabatangan .

Chemicals pollutants that are commonly found in Sabah's waterways come from either industries, farm, homes, laboratories and others. Chemicals such as nitrates, phosphates, salts, acids, oil and grease, chlorine compound, BOD, DO, lead, are commonly found in Sabah waterways. Chemical pollutants also come from pesticides that are used in agricultural farm, forestry or home lawns and recreational field such as golf courses. Pesticides contaminant are toxic and harmful to not only human but also to some fishes, shellfish, predatory birds. Chemical pollutants have been reported to have been detected in the Ranau water supply. Pesticides and herbicides from the nearby vegetable growing areas and the heavy metals pollution in the Sg, Liwagu are suspected to be the origin of these contaminants.

Biological pollutants in the form of faecal coliform (E-coli) algal (eutrophication) bacteria, viruses are also commonly found in rivers and other water sources. Report in the Water Resource Master Plan indicated that all raw water at town water supply have tested positive for E-coli.

Freshwater quality and Marine water quality standards are usually determined using the DOE water quality standards⁶⁵ as shown in Table 48 and Table 49.

Table 47: Main Pollutants of Concern in Sabah's Waterways.

Table 48: DOE interim Marine Water Quality Standards

Table 49: Interim National Water Quality Standards for Malaysia⁶⁶.

(Cont.) Table 49

7.3.2  Flood Prone Areas

Flood prone areas in Sabah are shown in Figure 35. As shown in the figure, virtually every district in Sabah is affected by flooding to some extent but areas most affected are mostly in the West Coast with the exception of the Kinabatangan River in the East Coast (refer to Section 3.3.7 ). The severity of flooding in these areas varies from year to year and also from river to river. The DID monitor flood in the low lying areas and compile annual records of such floods.

Actual flood occurrences have been reported in many of the river basins in Sabah. Actual flooding has been reported in the Kinabatangan River in the East Coast, Sg. Padas, Sg. Papar, Sg. Bandau, Sg. Inanam and Sg. Liwagu almost every year. During flood occurrence in the Kinabatangan River, the area most affected is the area in Bukit Garam. Other areas where actual flood have occurred in recent years are the Sg. Bandau and Keningau where a major flood occurred in 1996 (Tropical Storm Greg occurrence ).

Some of the flood protection works that have been carried out in Sabah include structural and non-structural measures. Structural measures include re-aligning or diversion of channels, and concretisation of channels. The non-structural flood protection measures involve installation of flood forecasting and warning systems and development control measures. Flood protection work are carried mainly to alleviate or mitgate flooding by means of improvement of drainage in flood prone areas.. These works are carried out by DID and JKR.

7.3.3  Catchments

Runoff

The Department of irrigation and Drainage (DID) in Kota Kinabalu has runoff stations to determine the rate of runoff and discharge for several rivers in Sabah. Records in the Water Resource Master Plan indicate that there are 27 stations for which data are available for runoff rates. Additional data for discharge and runoff were also supplied by DID for at least 10 stations. Of the 10 stations, only 4 rivers have discharge data for 5 years from 1993-97. The remaining rivers have data only for 1997.

Figure 35: Flood Prone Areas in Sabah

7.4  Groundwater

Data for groundwater investigation are held in the Geological Survey Department who is largely responsible for groundwater assessment in Sabah. Other investigations may also have been carried out by other agencies like JKR and the Water Department. Private agencies like Timatch Sdn. Bhd. also carries out their groundwater investigation. Groundwater investigation undertaken by the Geological Survey Department up until 1993 is shown in Table 50.

Presently, groundwater supply in Sabah is still used largely as a supplementary supply and only to nine water supply systems⁷². Only two towns, Kuala Penyu and Pulau Bumbun are currently using groundwater as a sole source of water supply.

Table 50: Regional Groundwater Investigation undertaken by the Geological Survey Department

Location	Type of System	Area Covered (ha)	No. of Holes	Total Metreage (m)
Kota Marudu	Alluvial	100,000	52	320
Tuaran	Alluvial	62,000	143	675
Beaufort	Alluvial	31,000	10	169
Sipitang	Beach	5,000	13	66
Kuala Penyu	Beach	8,000	18	140
Sikuati	Beach	20,000	?	?
Sandakan	Beach/Alluvial	50,000	?	?
Dent Peninsula	Alluvial	20,000	?	?
Lahad Datu	Alluvial	10,000	?	?

7.4.1  Storage

There are several groundwater storages in the coastal zone of Sabah that have been identified to have a potential for groundwater investigation. These are beach deposits, alluvial deposits, coral deposits, sedimentary rocks, igneous rocks and other types of rocks. Storage volume from each of these different storage vary considerably depending on the thickness of the aquifer and the thickness of the deposits. Currently, no groundwater assessments have been carried out on coral deposits, igneous rocks sedimentary rocks and other rocks, although extractions of groundwater from sedimentary rocks are ongoing and known to yield a significant amount in Sandakan. The two storage currently being assessed are the beach deposits and the alluvial deposits, Although the beach deposits occupy an extensive area in the coastal zone, groundwater storage in this deposit tend to be relatively small due to the shallow deposit above sea level and are also bounded by sea, tidal creeks and estuaries. Groundwater investigations that are carried out on beach deposit in Sabah are in Sipitang, Kuala Penyu and Sikuati.

Alluvial deposits are known to have a larger groundwater storage due to the deeper alluvial fill. It is also known to contain mostly freshwater resources throughout the whole section. Groundwater investigations conducted on alluvial deposit in Sabah are in Tuaran and Kota Marudu.

There is no data or information pertaining to the quantity or volume of groundwater reserves in any of the existing assessment sites.

Groundwater supply is largely dependent on rainfall for recharge. It was estimated that about 22% of annual rainfall percolates into the bedrock and are utilised as groundwater recharge⁷³. However the percolation rates may vary depending on the porosity of the soil. Groundwater can also easily be depleted during dry period or in areas where surface soil is impervious to water.

7.4.2  Groundwater Quality

There is no groundwater quality monitoring data available for any of the groundwater under investigation in Sabah to date. Monitoring programmes that are carried out are only to monitor the yield, the pressure and potential leaks. Nevertheless the quality of the groundwater are in constant threat by several contaminants that leach into the groundwater from either leaks in the sewer pipelines, accidental chemical or oil spills, seepage of sewage, runoff of animal wastes from feedlots, runoff of fertiliser, salts and other contaminants. The most common chemical contaminants that are found in ground water are nitrates that leached into the groundwater from fertiliser and from animal wastes from feedlots, pesticides and herbicides from agricultural farm, accidental chemical spill and from household activities. Bacterial leachates from animal feedlots, sewer leakage and sewage catchment areas are also commonly found to contaminate the groundwater.

7.4.3  Water Use

Presently groundwater is only used as a supplementary system. Of the 30 town water supply currently operated by the Water Department, only two systems are solely dependent on groundwater as a source of supply a supplementary supply for nine other systems. It is reported that as much as 370ML/day of groundwater is extracted for town water supply distribution. In Sandakan, it is reported that about 30% of the treated water distributed is abstracted from groundwater⁷⁴. No other data was available pertaining to the use of groundwater in Sabah.

7.5  Marine/ Estuarine Water

The marine ecosystem is divided into estuarine zone and the oceanic zone. The estuarine zone represents less than 10% of the total ocean area but contains 90% of all the marine life. The oceanic zone represents 90% of the total ocean area but support very little marine life. The water in the estuarine zone are shallow and therefore allows sunlight penetration for photosynthesis to occur among the vast population of phytoplankton, which support the life of marine life.

7.5.1  Hydraulics

Tidal

The tidal regime along the northwest coast of Borneo is a mixed diurnal/semidiurnal type, implying that there may be either one or two high waters per day depending upon the beating of the various tidal constituents. Generally, spring tides tend to show diurnal nature while neap tides appear semidiurnal. The maximum range is 2.4m. Tidal planes for Kota Kinabalu are given in Table 51.

Table 51: Tidal planes for Kota Kinabalu.

Tidal data from NE to SW of the West Coast of Sabah shows only relatively small gradients in tidal amplitude and phase which implies that the tidal waves propagate primarily in an onshore-offshore direction, and considerably less in the longshore direction. This is caused by the presence of the 3km deep trench lying offshore, and other regional geometry.

Historical data, supplemented by more recently acquired tidal measurements from Malaysian sources, are available from three different sources in the form of tidal constituents for a total of 25 stations between Miri and Kudat. The sources of this data are summarised in Table 52.

Table 52: Summary of the tidal data sources.

Water level records from the Malaysian Federal Hydrographic Department are available for the stations and periods shown in Table 53.

Table 53: Summary of water level records obtained from Malaysian Federal Hydrographic Department.

Due to seasonal processes i.e. monsoon-generated currents and the complex three dimensional shelf processes occurring where the coastal shelf meets the deep water of the South China Sea, Net currents are present off the Western Sabah coast. The processes occurring on the outer coastal shelf have considerable influence on nearshore flows.

It is believed that a great deal of data exists to document the current environment offshore of Sabah, Brunei and Sarawak but these data were gathered by the oil companies whose fields occupy these waters: (Shell and Petronas). The bulk of these data is taken by Shell Sarawak Berhad (SSB), but is officially the property of Petronas and are not available in Sabah. Therefore, there is essentially no data to document the offshore current environment for the Sabah. A complete evaluation of the regional currents on the coastal shelf of Sabah requires the release of the field data that is held at the Shell/Petronas. The only information available is the notations in the Admiralty Charts. From the little information available, it is known that monsoon currents are present on the shelf area, but the monsoon seasons are not as distinct as in other areas of SE Asia. Also, despite the presence of seasonal monsoons, the current speed and direction on the coastal shelf are highly variable. The highest currents encountered in the shelf region do not originate from the monsoons, but from the three dimensional interactions between the cold, saline deep water of the South China Sea and the relatively warmer and brackish water of the coastal shelf. These shelf processes may be induced by meteorological disturbances in other areas of the South China Sea, which result in dense water being forced onto the coastal shelf.

7.5.2  Marine Water quality

All natural and human wastes ultimately end up in the oceans. Used and contaminated water from homes, factories, industries and farms flows into rivers and streams will eventually end up in the ocean. Apart from liquid wastes, solid wastes such as plastics, cans, bottles and other solid wastes also end up in the ocean floor and estuaries. Although some pollutants such as DDT and PCB's are global, the major pollution problems are around the coastline - the estuaries, bays, harbours and the mouth of rivers. Many types of waste are disperse and broken down by chemical cycle in the ocean systems. Sewage to a certain load can be diluted by the ocean but a large discharge especially near the coast can overload the purifying systems. Also, these natural processes cannot easily degrade the many of the plastics, pesticides, and other chemicals that end up in the marine water.

Data on Marine Water Quality in Sabah are limited only to those areas where development is on going and EIA studies have been carried out. All the three common types of pollutants, physical, biological, and chemical are found in Sabah coastal zones.

It can be said that most of Sabah coastal areas are gravely polluted by physical contaminants such as plastics, cans, bottles and a hosts of other solid wastes that are thrown into the coastal areas from squatters along the coast, from commercial areas, markets, homes and from ships and boats that navigate the marine waters. Physical contaminants such as soil from natural erosion, or runoff are also found to pollute the marine waters especially in the estuary areas.

Other serious contaminants found in Sabah marine water are biological contaminant such as sewage effluents that that come from municipal sewer lines, indiscriminate dumping of raw sewage by squatters in the coastal areas and from animal farms.

Chemical contaminants from industries, pesticides agricultural farm and accidental dumping are also found in the Marine waters.

7.5.3  Extreme Events

Occurrence of extreme events have been recorded in Sabah. Tropical Storm Greg that occurred in Sabah in December 1996 left much damage not only to estuaries but also to much of the marine habitats and the coastline. Extreme events such as the Tropical Storm Greg is important to take into account in coastal zone planning. Data pertaining to this particular event was not supplied to the ICZM unit but it is believed that some information pertaining to the damages resulting from this events do exists in some agencies. This information is vital to the coastal profile in order to prepare an effective planning of the coastal zone.

7.5.4  Bathymetry

There is very little information on the offshore bathymetry of Sabah. Although bathymetric data is readily available for the West Coast of Sabah in the form of navigation charts from the British Admiralty, a large areas are covered only by historical leadline surveys dating back to the early 1900’s, and by occasional soundings made by ships during passage. The sole source of bathymetric data are from the Admiralty charts but do not cover the entire coast of Sabah. There are however, some bathymetric survey conducted recently on some specific areas like the Kota Kinabalu Water front, Likas Bay area and the Lok Kawi Beach area. It is also believed that some specific bathymetric survey have been conducted for areas in the Tuaran coastal areas where many of the new resort developments have recently been established. Data for these areas may be sitting with the developers or Survey Consultants to these development.

The bathymetric condition of the Likas Bay and Lok Kawi is discussed here for which survey has been conducted. Caution must be exercised not to interpret this information as a representative of the Bathymetry of Sabah.

The offshore bathymetry of the Likas Bay area is generally governed by the degree of exposure to wave climates and the presence of nearby features such as headlands and offshore islands. The bathymetry of the waters fronting the existing coastline is gentle sloping (evidenced at low tide, by the exposure of the nearshore area). The coastline towards the port has a steep gradient due to the presence of port facilities⁷⁵.

According to the National Coastal Erosion Study (NCES), the shoreline between Tg. Kaitan (situated north of Sapangar Bay) and Tg. Aru, is characterised by relatively small pocket beaches and protected reclaimed land in the Kota Kinabalu area. This reach includes Sapangar Bay, Gaya Bay covering the coast sheltered by Sapangar Island, Gaya Island, Sapi Island and Mamutik Island.

For the Lok Kawi Beach, 15 miles south of Kota Kinabalu, the offshore bathymetry is also governed by the degree of exposure to wave climates, the presence of nearby features such as headlands and offshore islands. The bathymetry of the waters fronting the existing coastline is gentle sloping. These factors encourage the settling of sediments coming from sediment discharge from Sg. Kinarut The shoreline of the Lok Kawi beach is part of a series of long shallow bays typically found along the west coast of Sabah. According to the National Coastal Erosion Study (NCES), the shoreline between Kg. Menumbok (situated on the south-western tip of Sabah) and Tg. Aru coast is characterised by a sandy beach coast with beaches of various length bordered by headlands. The shoreline orientation varies from 180^o to 260^o between Tg. Aru and Kuala Papar⁷⁶.

7.6  Information Issues

A complete data for river discharge, runoff and sediment load are needed before a complete and accurate presentation of the present situation of the this valuable water resource can me made. Data for river gauging stations provided by DID have several shortcomings to be used for analysis. First, most of the gauging stations are fairly far upriver that discharge measured does not include the effect of the entire catchment. The data are collected also have too many gaps that it is difficult to make any meaningful analysis. For surface water quality data, the coverage of data supplied by DOE are too sparse and therefore cannot be used as a representative of the whole area. There was no data available for groundwater quality checking. This is an important issue as groundwater is important source of water and quality checking is important for this resource.

As for Marine water, water level data and net current data are still lacking or data are held confidential by some agencies for example net current data is held by Shell/Petronas. These data are extremely important for coastal planning.

63The Water Resource Master Plan Final Report was prepared in 2 volumes and completed in 1994. Part of the information used in this chapter was extracted from the Master Plan

64Source of Data: Water Resource Master Plan for Sabah Vol. 1 p. 4.2

65DOE Interim Water Quality Marine Water and National Water Quality Standard for Malaysia.

68Class II A. represents water bodies of good quality. Most existing raw water supply sources come under this category. In practice, no body contact activity is allowed in this water for prevention of probable human pathogens. There is a need to introduce another class for water bodies not used for water supply but of similar quality which may be referred to as Class IIB. The determination of Class IIB standard is based on criteria for recreational use and protection of sensitive aquatic species.

71Class V represents other waters which do not meet any of the above uses.

72Data from Water Resource Master Plan.

74Sandakan Coastal Profile, Ch 5 p. 5-4

75Preliminary EIA for Likas Bay Reclamation Project.

76Preliminary EIA for Lok Kawi Beach Reclamation Project.