Manukan Island Research Articles

Distribution and Abundance of Marine Debris on Intertidal Zone at Three Selected Small Islands, Sabah

The issue of marine debris has become worldwide attention since it occurs almost everywhere globally Thus, it is crucial to focus on this area to sustain the life below the water as stated by United Nations (SDG 14). This study evaluated the distribution, abundance, and composition of marine debris in three selected islands at Sabah namely Manukan, Mamutik and Sapi Islands. Marine debris was identified according to its categories as stated by the Department of Environment (DOE). The study was carried out to compare the waste abundance of three islands since the different beach types represent various activities that produce debris. The sampling design was conducted with two plot areas plotted and observed on each island for three consecutive weeks. Based on the assessment done, Mamutik Island recorded the most abundance of marine debris with 12.185 kg (66.2%) of debris found followed by Manukan Island with 5.487 kg (29.8%) of debris and Sapi Island with 0.746 kg (4.1%). It was observed that plastic debris especially plastic bags, plastic bottles, plastic straws, general plastics, polystyrene, and plastic cups were the main contributors to marine debris pollution. While among all the three islands studied, Sapi Island is considered the cleanest and smallest Island compared to others since the location of this island is quite far from the mainland. The solid and waste management on each island has been identified in order to formulate a new strategy to reduce the impact of marine debris on the intertidal zone especially on human health and the environment. These studies have provided a clear understanding of the distribution of marine debris in these islands. Several recommendations and suggestions have been listed to reduce and prevent marine debris pollution.

DETERMINING TOURIST’S CARRYING CAPACITY BASED ON ECOLOGICAL APPROACH IN TUNKU ABDUL RAHMAN PARK, MALAYSIA


 
 
 
 
 
 
 
 ARTICLE INFO
 Article History:
 Received: 9/3/21
 Accepted: 19/4/21
 Published: 31 Dec 21
 
 
 
 
 
 
 
 
 Tunku Abdul Rahman Park (TARP) is a Marine Protected Area (MPA) and a famous tourist destination in Sabah. The possible long-term negative impacts on the ecology and sustainability of the Park due to the very high number of tourists is of much concern to the Park management authority. This study was conducted to determine the ecological and tourism carrying capacity in three islands in TARP, Manukan, Mamutik and Sapi islands. The Effective Carrying Capacity (ECC) concept is applied in this study, in which the results are expected to provide the Park Authority with data and effective management actions. Calculation of carrying capacity in this study was based on three distinct visiting patterns or seasons: i) Regular season; ii) High season, and iii) Festive season in order to ensure optimal tourists' satisfaction and revenue, while still maintaining ecological sustainability. ECC was calculated after considering the various limitations imposed by physical, climate, ecological, and management capabilities. Land and ocean areas were considered and calculated separately as they occupied different variables. Our findings showed that Manukan island recorded the highest ECC, while Mamutik and Sapi island shared almost similar ECC value. Optimization of Carrying Capacity (CC) in different seasons was also achieved with a few Correction Factor (CF) adjustments. It shows that Festive season recorded the highest ECC, followed by High Season and Regular Season. The ECC obtained was suggested to be implemented to TARP management as to preserve and sustain the ecological value of the Park.

AN INVESTIGATION OF TUNKU ABDUL RAHMAN MARINE PARK, SABAH'S ATTRACTIONS AND TOURISM INFRASTRUCTURE MANAGEMENT

Tunku Abdul Rahman Marine Park (TLTAR) is a marine park established under the Establishment of Marine Parks Malaysia Order 1994 of the Department of Fisheries to conserve marine resources and develop tourism. It consists of five islands, namely Manukan Island, Mamutik Island, Sapi Island, Sulug Island, and a portion of Gaya Island. The marine park has an area of 4,929 hectares, of which two-thirds are submerged. The purpose of the study is to investigate the characteristics of tourist attractions and tourism infrastructure in TLTAR, Sabah. The study involved 249 respondents, including locals who have visited TLTAR. The majority of respondents (71.5%) were male, 75.5% were under 30 years old, 68.7% were single, and over 50% had secondary education. The results of this study revealed that there were three main attractions that attracted visitors to TLTAR, which included the beauty of the beach and water surrounding it, the peaceful island environment, and recreational activities such as snorkelling, scuba diving, and picnicking. The island environment, particularly its beach, and the safety of the island, particularly perceived threats from certain parties and crimes, are also a few factors that need to be addressed in order for visitors to continue visiting TLTAR. In terms of the level of tourism infrastructures, the findings indicate that the recreational facilities, boat services, and jetty provided are better than those offered by others in Malaysia. The findings of the study are important for policymakers and marine park development planners in ensuring more sustainable tourism management and creating enjoyable and satisfaction for all visitors.

Characterization of Aromatic Hydrocarbons in Tropical Coastal Water of Sabah, Borneo

The presence of carcinogenic compounds in the coastal waters was monitored to assess the health effects to human and the marine environment. The details on the level of hydrocarbon contamination in the coastal waters of some small islands and the port in Kota Kinabalu were provided to initiate the management and monitoring plan for ecosystem management and restoration of the target places. This paper reports the occurrences of oil and grease and 16 USEPA listed polyaromatic hydrocarbons in the selected locations of coastal waters of Sabah. A baseline reading on the oil and grease level was established using partition-gravimetric method while detection for polyaromatic hydrocarbons was studied using GC-MS. The level of oil and grease tested were all above the limit set by the Malaysian interim standards (0.04 mg/L), while the level of monitored polyaromatic hydrocarbons were still within an acceptable level. Most polyaromatic hydrocarbons monitored were detected in trace amount and many compounds were found to be below the detection limit of 0.02 I¼g/mL. The highest concentration of total polyaromatic hydrocarbons detected was 1.16 I¼g/mL, which was detected in the coastal waters of Manukan Island. Pyrene, benzo (a) anthracene and chrysene were detected in trace amounts in all locations. The levels of monitored carcinogenic hydrocarbon compounds were below the detection limit. Though detected at low levels, the presence of these elements in the coastal water is a cause for concern, hence continuous monitoring is recommended. The cumulative concentration of these compounds in molluscs and fish should be initiated to determine the accumulated level and the xenobiotic effect to humans and marine fauna. The main contributor of these pollutants was identified to originate from boating and shipping related activity in the vicinity of these area.

Delineation of temporal variability and governing factors influencing the spatial variability of shallow groundwater chemistry in a tropical sedimentary island

Summary An attempt has been made to delineate the temporal variability and factors governing the shallow groundwater chemistry using analysis of variance (ANOVA) and multivariate analysis notably R-mode factor (FA) and hierarchical cluster analysis (HCA). Subsequently, geostatistical isoplethic maps were applied to convey better understanding on the distribution of selected groundwater parameters. The Manukan Island’s shallow aquifer with sedimentary setting that constantly abstracted for freshwater supply has been selected for this study. One-way ANOVA suggested that neither changes of tide level nor rainfall volume appeared to exert significant influence on the groundwater chemistry of the small island. Rather, the groundwater chemistry was greatly governed by influence from seawater intrusion, which characterized by considerable amount of Ca, Na, and Cl. Such condition was well explained by a Piper diagram, where most plots were situated at the middle diamond shaped diagram, indicating mixing condition. FA likewise revealed that the shallow groundwater receives marked influence from carbonate dissolution and silicate weathering processes, especially boreholes located in the inland area. This can be clearly noted from the distinct groupings of relationships among different factors. HCA classified boreholes into three groups according to their locations in the coastal area, suggesting significant chemical variations between boreholes with distance from coast. Such distribution pattern was particularly evident in the isoplethic map. Overall, it appears that the shallow groundwater in the tropical island is not an appropriate source for drinking water in concern to its exceptionally high salinity and several elevated minor elements (Mn, Pb, and Se). For this, it is suggested that efforts in exploring other alternative sources should be performed outright.

The Influence of Seawater on the Chemical Composition of Groundwater in a Small Island: The Example of Manukan Island, East Malaysia

Abstract ARIS, A.Z.; PRAVEENA, S.M., and Abdullah M.H., 2012. The influence of seawater on the chemical composition of groundwater in a small island: the example of Manukan Island, East Malaysia. Manukan Island in Sabah, Malaysia, is characterized as a small, unique island where groundwater is a major source for domestic water and other water-related activities. Hydrochemical studies were carried out in the island with the objective of identifying the influence of seawater on the chemical composition of groundwater in Manukan Island via ionic ratios and saturation states. From the calculated ionic ratios, the chemical composition of groundwater in the study area in general is influenced by seawater intrusion. The Na/Cl ratios ranged from 0.10–2.70, implying that the fresh groundwater in Manukan Island was affected by the seawater signature. Values close to ratio of seawater indicate a recent intrusion of seawater into the aquifer. Saturation index values show that the cation exchange process is found to c...

Modeling of Water Balance Components in a Small Island via a Numerical Model Application

Abstract PRAVEENA, S.M.; ABDULLAH, M.H.; BIDIN, K., and ARIS, A.Z., 2012. Modeling of water balance components in a small island via a numerical model application. A numerical model (SEAWAT-2000) was selected to estimate the water balance components in the low-lying area of Manukan Island. The water balance components of the current situation have shown that decreasing freshwater storage is due to irregularities in the patterns of recharge rate and overpumping. Scenarios 1 and 2 were selected for factors that affect the water balance components in the current situation. The water balance components in Scenarios 1 and 2 have illustrated sustainable management and utilization of groundwater resources in the study area. A valuable tool to restore groundwater storage has been demonstrated in Scenario 2, which represents the impact of future El Nino events. The best artificial recharge method must be selected with consideration given to other important factors. Extra meteorological and water usage data will ai...

Numerical simulation of seawater intrusion in Manukan Island, East Malaysia

PurposeThis paper aims to define the current and potential extent of seawater intrusion in Manukan Island under different scenarios of varying recharge and pumping rates. The calibrated model was also used to predict the extent of seawater intrusion in low lying area of Manukan Island for two years with all conditions assumed to remain the same as those in December 2009.Design/methodology/approachDifferent scenarios of varying recharge and pumping rates based on threats received by Manukan Island were investigated. El‐Nino events and overpumping are represented by varying recharge and pumping rates. Simulation was done using SEAWAT‐2000, the latest modeling software available in groundwater modeling that couples flow and transport together.FindingsThe seawater‐freshwater mixing ratio moves landwards after two years of simulation in Scenario 1. In order to control overpumping in this study area, Scenario 2 has resulted in backward movement of the 1.4 percent seawater‐freshwater mixing ratio toward the coast after two years of prediction. The current contamination of the coastal aquifers by seawater intrusion will be more severe with an impact of El‐Nino events on groundwater resources depletion in Scenario 3. Reductions of pumping and recharge rates in Scenario 4 have worsened the seawater intrusion problem. With the aid of artificial recharge in Scenario 5, highest hydraulic heads and lowest chloride concentration were observed.Practical implicationsThe sustainable groundwater management selected for Manukan Island's current situation will be Scenario 2. In view of the effects of El‐Nino events in the future, Scenario 5 can be implemented to restore groundwater resources. The numerical model has showed the groundwater condition during El‐Nino events and overpumping illustrated that simulation modeling is an excellent tool to understand the behavior and management of an aquifer system. The output of simulation modeling via numerical model provides a framework toward groundwater management. Thus, current study output with similar approach which will restore groundwater (artificial recharge and reduction of pumping rate) can be applied in other small islands of similar hydrogeological condition and stresses for the purpose of groundwater resource protection.Originality/valueBriefly, these findings will effectively contribute to water policy analysis, planning and management in the study area to combat current as well as future seawater intrusion problem.

Sustainable groundwater management on the small island of Manukan, Malaysia

Numerical models are capable of simulating various groundwater scenarios and relate it towards groundwater management. This paper focuses on numerical modeling and water balance approaches in the search for a sustainable management plan in Manukan Island. The impacts of pumping and recharge rates represented by groundwater scenarios were investigated by means of hydraulic heads, chloride concentrations and water balance components. Overpumping and inconsistency in recharge rate are the stresses shown in Scenario A. Scenario B involved with reduction pumping rate by 25% has shown an increase in groundwater levels, chloride concentration and groundwater storage. Scenario C showed the most promising finding compared with Scenarios A and B. Highest hydraulic heads, lowest chloride concentration (1,552.2 mg/L) and positive groundwater storage (254.3 m3/day) were obtained in Scenario C. Chloride concentration in pumping wells still exceeds World Health Organization International Standard limit in Scenario C which illustrates an additional water treatment is needed. Nevertheless, in view of a compromise groundwater management plan in study area, Scenario C is the best plan so far to protect the groundwater resources in the study area. More understanding of the artificial recharge method (percolation tank) and study site by means of modeling studies is needed. Additionally, further progress is needed in obtaining the water usage data from each part to determine the best pumping rate. A sustainable groundwater management plan is crucial to maintain the natural resources and social benefits as well as to protect the ecological balance of Manukan Island.

Understanding of groundwater salinity using statistical modeling in a small tropical island, East Malaysia

This paper presents an understanding of groundwater salinity by identification of effective factors using chemometric methods (cluster analysis and multiple linear regressions) in Manukan Island, Sabah. Local groundwater and environmental properties were used to explore the effective factors of groundwater salinity. Cluster analysis showed salinity and chloride illustrated the highest similarities. Electrical conductivity and total dissolved solids were also grouped in the same cluster. Seawater is the only chloride source in groundwater of Manukan Island demonstrated an indication of seawater mixing in freshwater. It is an effect of upward movement of the seawater by pumping activities. Precipitation and evapotranspiration (environmental condition) with hydraulic heads were clustered together to show that they also influence salinity concentration in groundwater. Multiple linear regressions showed descending order of the factors from chloride (the largest contribution) to evapotranspiration (the smallest contribution) and illustrated the contribution to groundwater salinity in Manukan Island. The integrated results using chemometric methods have provided a way to identify the effective factors on groundwater salinity. This similar approach and resulting equation can be applied in other small tropical islands with alike hydrogeological condition and limited information available for a better understanding of its groundwater salinity.

Statistical approaches and hydrochemical modelling of groundwater system in a small tropical island

The aquifer of Manukan Island of Borneo, Malaysia had been found to be affected by seawater intrusion associated with excessive groundwater exploitation. This research attempted to characterize the chemistry of an impacted zone in the island using factor analysis (FA), cluster analysis (CA) and a hydrochemical model package (PHREEQC). The factor scores were used to plot the spatial map and to group the relationships among the monitoring wells using CA. The results of FA analysis revealed that the three main processes associated with the seawater intrusion event are aquifer salinization, cation exchange process and redox sequences. Output from the PHREEQC simulation was used to support the findings from the multivariate analysis.

Stability Behavior and Thermodynamic States of Iron and Manganese in Sandy Soil Aquifer, Manukan Island, Malaysia

A total of 20 soil samples were collected from 10 boreholes constructed in the low lying area, which included ancillary samples taken from the high elevation area. Redox processes were investigated in the soil as well as groundwater in the shallow groundwater aquifer of Manukan Island, Sabah, Malaysia. Groundwater samples (n = 10) from each boreholes were also collected in the low lying area to understand the concentrations and behaviors of Fe and Mn in the dissolved state. This study strives to obtain a general understanding of the stability behaviors on Fe and Mn at the upper unsaturated and the lower-saturated soil horizons in the low lying area of Manukan Island as these elements usually play a major role in the redox chemistry of the shallow groundwater. Thermodynamic calculations using PHREEQC showed that the groundwater samples in the study area are oversaturated with respect to goethite, hematite, Fe(OH)3 and undersaturated with respect to manganite and pyrochroite. Low concentrations of Fe and Mn in the groundwater might be probably due to the lack of minerals of iron and manganese oxides, which exist in the sandy aquifer. In fact, high organic matters that present in the unsaturated horizon are believed to be responsible for the high Mn content in the soil. It was observed that the soil samples collected from high elevation area (BK) comprises considerable amount of Fe in both unsaturated (6675.87 mg/kg) and saturated horizons (31440.49 mg/kg) compared to the low Fe content in the low lying area. Based on the stability diagram, the groundwater composition lies within the stability field for Mn2+ and Fe2+ under suboxic condition and very close to the FeS/Fe2+ stability boundary. This study also shows that both pH and Eh values comprise a strong negative value thus suggesting that the redox potential is inversely dependent on the changes of pH.

Groundwater Assessment at Manukan Island, Sabah: Multidisplinary Approaches

A rapid increase in the number of tourists has placed a heavy demand for freshwater on Manukan Island, a small island located offcoast of Kota Kinabalu, Sabah. Hydrochemical and numerical approaches have been applied in this study to evaluate the groundwater quality of unconfined aquifer lying in Manukan Island, Sabah, East Malaysia. This is vital to enhance better understanding about groundwater management. Hydrochemical analysis output indicated NaCl water type in sampling locations. Seawater intrusion is marked by its relatively high Na+, Mg2+, Cl− and SO4 2− concentrations. Hydrochemical analysis output clearly showed the influence of seawater in groundwater of Manukan Island. The numerical model output proved the influence of seawater in groundwater of Manukan Island by indicating the upconing process at the beneath of the pumping well. Current status of seawater intrusion in Manukan Island is about 14.6% of freshwater and seawater mixing ratio in low lying area of Manukan Island as simulated by SEAWAT-2000 model output. Numerical model SEAWAT-2000 output showed clearly that the upconing process is the possible route of seawater to influence the fresh groundwater aquifer chemistry in Manukan Island. The results have enhanced the current understanding of seawater intrusion in the study area. Future studies will focus on using numerical models to simulate and suggest suitable groundwater management plans in Manukan Island.

Saturation states of carbonate minerals in a freshwater-seawater mixing zone of small tropical island’s aquifer

Groundwater is a crucial resource on the Manukan Island as it is the only source of freshwater available on the island. The aquifer has deteriorated to a high degree, during the last decade. Nine domestic wells were sampled from March 2006 to January 2007 to probe the hydrochemical components that influence the water quality. Geochemical data on dissolved major constituents in groundwater samples from the Manukan Island revealed the main processes responsible for their geochemical evolution. The results using statistical analyses, graphical method and numerical model output (PHREEQC) showed that the groundwater was chemically highly enriched in Na and Cl, indicative of seawater intrusion into the aquifer as also supported from the Na-Cl signature on the Piper diagram. From the PHREEQC simulation model, calcite, dolomite and aragonite solubility showed positive values of the saturation indices (SI), indicating supersaturation which led to mineral precipitation condition of water by these minerals.

Modeling for Equitable Groundwater Management

Freshwater lens on small islands may easily be overexploited or polluted due to overdrafts of fresh water by pumping which causes drawdown of the water table a rise or up-coning of the saltwater interface. Present study is concerned with using a three-dimensional finite-difference numerical model to simulate the groundwater flow and transport model to predict the behavior of groundwater system in Manukan Island. The simulations were done using variable density SEAWAT-2000 for three selected pumping schemes.Hydraulic heads (groundwater level) is the highest at the center of the island and decreases in radial shape towards the coast in all the pumping schemes (PS1-PS3). The chloride concentration in the studied aquifer increased by 98.7% in the pumping well if the pumping rate is doubled by the current (PS2 to PS3). The 1.4% seawater-freshwater mixing moves further forward to inland about 1.6m when the current pumping rate was doubled whereas moves backward to sea about 1.7m if the current pumping rate is reduced by 50%. This preliminary model of Manukan island aquifer shows that an overexploitation of groundwater in Manukan Island contributes to the seawater intrusion. Adjusting the future groundwater pumping scheme and improving groundwater management strategies are necessary to protect the freshwater aquifers. The current numerical model is a reasonable representation of the aquifer in Small Island which can be used in similar small islands with similar hydrogeological conditions in elsewhere.

Groundwater resources assessment using numerical model: A case study in low-lying coastal area

The impacts of climate change and human pressure in groundwater have been greatest threats facing small islands. This paper represents a case study of groundwater responses towards the climate change and human pressures in Manukan Island Malaysia. SEAWAT-2000 was used for the simulations of groundwater response in study area. Simulations of six scenarios representing climate change and human pressures showed changes in hydraulic heads and chloride concentrations. Reduction in pumping rate and an increase in recharge rate can alter the bad effects of overdrafts in Manukan Island. In general, reduction in pumping rate and an increase in recharge rate are capable to restore and protect the groundwater resources in Manukan Island. Thus, for groundwater management options in Manukan Island, scenario 2 is capable to lessen the seawater intrusion into the aquifer and sustain water resources on a long-term basis. The selection of scenario 6 is the preeminent option during wet season. The output of this study provides a foundation which can be used in other small islands of similar hydrogeological condition for the purpose of groundwater resources protection.

Hydrochemical changes in a small tropical island’s aquifer: Manukan Island, Sabah, Malaysia

Small islands groundwater are often exposed to heavy pumpings as a result of high demand for freshwater consumption. Intensive exploitation of groundwater from Manukan Island’s aquifer has disturbed the natural equilibrium between fresh and saline water, and has resulted increase the groundwater salinity and leap to the hydrochemical complexities of freshwater–seawater contact. An attempt was made to identify the hydrochemical processes that accompany current intrusion of seawater using ionic changes and saturation indices. It was observed that the mixing between freshwater–seawater created diversity in geochemical processes of the Manukan Island’s aquifer and altered the freshwater and seawater mixture away from the theoretical composition line. This explained the most visible processes taking place during the displacement.

Controlling factors of groundwater hydrochemistry in a small island’s aquifer

Factor analysis was applied to the hydrochemical data set of Manukan Island in order to extract the principal factors corresponding to the different sources of variation in the hydrochemistry. The application of varimax rotation was to ensure the clear definition of the main sources of variation in the hydrochemistry. The geochemical data of dissolved major, minor and trace constituents in the groundwater samples indicates the main processes responsible for the geochemistry evolution. By using Kaiser normalization, principal factors were extracted from the data for each location. The analysis reveals that there are four sources of solutes: (1) seawater intrusion; (2) leaching process of underlying rock mediated by pH; (3) minerals weathering process and (4) dissolution of carbonate minerals characterized by high loadings of Ca, Zn and Mg. Such processes are dominated by the significant role of anthropogenic impact from the over abstraction of fresh water from the aquifer. Those factors contributed to the changes of the groundwater geochemistry behavior explain the effect of rising extraction of freshwater from the aquifer.