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The primary environmental impact caused by seawater intake operation is marine life impingement resulting from the intake velocity. Environmental Protection Agency (EPA) of United State has regulated the use of velocity cap fitted at intake structures to reduce the marine life impingement. The engineering design parameters of velocity cap has not been well explored to date. This study has been set to determine the fundamental relationships between intake velocity and design parameters of velocity cap, using computational fluid dynamic (CFD) model. A set of engineering design criteria for velocity cap design are derived. The numerical evidence yielded in this study show that the velocity cap should be designed with vertical opening (Hvc) and horizontal shelf (ℓvc). The recommended intake opening ratio (Or) shall be 0.36 Vr−0.31, where Or = Hvc/ℓvc and Vr =V0/Vpipe. Vo is the velocity at the intake window and Vpipe is the suction velocity at the intake pipe. The volume ratio (ωr) between the velocity cap (ωvc) and intake tower (ωIT) is recommended at 0.11 Vr−1.23. The positive outlooks that yielded from this study can be served as a design reference for velocity cap to mitigate the detrimental impacts from the existing intake structure.
Lee Hooi Chie; Ahmad Khairi Abd Wahab. Derivation of Engineering Design Criteria for Flow Field Around Intake Structure: A Numerical Simulation Study. Journal of Marine Science and Engineering 2020, 8, 827 .
AMA StyleLee Hooi Chie, Ahmad Khairi Abd Wahab. Derivation of Engineering Design Criteria for Flow Field Around Intake Structure: A Numerical Simulation Study. Journal of Marine Science and Engineering. 2020; 8 (10):827.
Chicago/Turabian StyleLee Hooi Chie; Ahmad Khairi Abd Wahab. 2020. "Derivation of Engineering Design Criteria for Flow Field Around Intake Structure: A Numerical Simulation Study." Journal of Marine Science and Engineering 8, no. 10: 827.
The impact of sea level rise (SLR) on a mangrove island ecosystem was investigated by projecting future increase in tidal inundation at the island. The aims of this study is to simulate the potential mangrove response under several conditions of SLR scenarios for the year 2050 and 2100. Processed WordView-2 and IFSAR images were used in the analysis. Segmentation and classification processing were conducted using SPRING 5.2 software while inundation was simulated using ArcGIS 9.3. A series of mangrove migration map for 2050 and 2100 SLR scenarios showed an adjustment to tidal inundation classification due to the increased seawater level. Mangroves from the higher zone (Z4) migrated into the lower zone (Z2 and Z3) as a response to SLR. In the worst-case scenario, more than 25% of the mangrove forest is predicted to be permanently submerged due to a 1.3 m sea level rise. The total land loss in the year 2100 was estimated at 73.52ha (Case study 1) and 148.92ha (Case study 2). The worst-case scenarios will possibly lead to the extinction of Xylocarpus moluccensis when Z4 starts to be completely inundated during the 2050 SLR projection. In conclusion, the findings showed that the tolerance to seawater inundation of different mangrove species determines its responses and migration pattern.
D.S.M. Ishak; A.K. Abd Wahab; S.Y. Teh; M.H. Jamal. Projected ecosystem response to the anticipated effects of sea level rise. Physics and Chemistry of the Earth, Parts A/B/C 2020, 120, 102934 .
AMA StyleD.S.M. Ishak, A.K. Abd Wahab, S.Y. Teh, M.H. Jamal. Projected ecosystem response to the anticipated effects of sea level rise. Physics and Chemistry of the Earth, Parts A/B/C. 2020; 120 ():102934.
Chicago/Turabian StyleD.S.M. Ishak; A.K. Abd Wahab; S.Y. Teh; M.H. Jamal. 2020. "Projected ecosystem response to the anticipated effects of sea level rise." Physics and Chemistry of the Earth, Parts A/B/C 120, no. : 102934.
The severity and frequency of short-duration, but damaging, urban area floods have increased in recent years across the world. Alteration to the urban micro-climate due to global climate change impacts may also exacerbate the situation in future. Sustainable urban stormwater management using low impact development (LID) techniques, along with conventional urban stormwater management systems, can be implemented to mitigate climate-change-induced flood impacts. In this study, the effectiveness of LIDs in the mitigation of urban flood are analyzed to identify their limitations. Further research on the success of these techniques in urban flood mitigation planning is also recommended. The results revealed that LIDs can be an efficient method for mitigating urban flood impacts. Most of the LID methods developed so far, however, are found to be effective only for small flood peaks. They also often fail due to non-optimization of the site-specific and time-varying climatic conditions. Major challenges include identification of the best LID practices for the region of interest, efficiency improvements in technical areas, and site-specific optimization of LID parameters. Improvements in these areas will allow better mitigation of climate-change-induced urban floods in a cost-effective manner and will also assist in the achievement of sustainable development goals for cities.
Sahar Hadi Pour; Ahmad Khairi Abd Wahab; Shamsuddin Shahid; Asaduzzaman; Ashraf Dewan. Low impact development techniques to mitigate the impacts of climate-change-induced urban floods: Current trends, issues and challenges. Sustainable Cities and Society 2020, 62, 102373 .
AMA StyleSahar Hadi Pour, Ahmad Khairi Abd Wahab, Shamsuddin Shahid, Asaduzzaman, Ashraf Dewan. Low impact development techniques to mitigate the impacts of climate-change-induced urban floods: Current trends, issues and challenges. Sustainable Cities and Society. 2020; 62 ():102373.
Chicago/Turabian StyleSahar Hadi Pour; Ahmad Khairi Abd Wahab; Shamsuddin Shahid; Asaduzzaman; Ashraf Dewan. 2020. "Low impact development techniques to mitigate the impacts of climate-change-induced urban floods: Current trends, issues and challenges." Sustainable Cities and Society 62, no. : 102373.
Trends in reference evapotranspiration (ETo) have been found highly diverse in different regions of the globe due to the contradictory changes in the meteorological variables that define ETo. Despite a significant impact of ETo in water resources and ecology, knowledge on the changes and the cause of the changes in ETo is very limited in tropical regions. The trends in ETo, the factors influencing the changes in ETo and the change point (year) that made the trend significant were evaluated in this study for tropical peninsular Malaysia. The modified version of Mann-Kendall (MK) test was used for the assessment of unidirectional changes in ETo and the driving meteorological variables. The innovative trend analysis (ITA) was conducted to understand the variations in change with time. Sobol's method was used to measure the sensitivity of ETo to different meteorological factors and the Sequential MK test was employed to identify the change point. The study revealed an increase in annual (0.009–0.026 mm/year) and seasonal (0.014–0.027 mm/year during southwest monsoon and 0.015–0.074 during northeast monsoon) ETo in peninsular Malaysia which contradicts to evapotranspiration paradox found in many regions. The minimum temperature (31.5–48.2%) was found as the most influencing factor followed by wind speed (15.1–32.8%.) in defining ETo in peninsular Malaysia. Analysis of ITA and sequential MK test results revealed that the rise in minimum temperature is the major cause of the increase in ETo in peninsular Malaysia. A faster rise in minimum temperature after 1981–1985 caused an increase in ETo after 1993–1996 in most of the locations. The minimum temperature in the region was noticed to rise much faster compared to the global average which indicates a large and continuous increase in ETo due to global warming and thus, reduction in atmospheric water balance in peninsular Malaysia.
Sahar Hadi Pour; Ahmad Khairi Abd Wahab; Shamsuddin Shahid; Zulhilmi Bin Ismail. Changes in reference evapotranspiration and its driving factors in peninsular Malaysia. Atmospheric Research 2020, 246, 105096 .
AMA StyleSahar Hadi Pour, Ahmad Khairi Abd Wahab, Shamsuddin Shahid, Zulhilmi Bin Ismail. Changes in reference evapotranspiration and its driving factors in peninsular Malaysia. Atmospheric Research. 2020; 246 ():105096.
Chicago/Turabian StyleSahar Hadi Pour; Ahmad Khairi Abd Wahab; Shamsuddin Shahid; Zulhilmi Bin Ismail. 2020. "Changes in reference evapotranspiration and its driving factors in peninsular Malaysia." Atmospheric Research 246, no. : 105096.
Although a significant number of studies have evaluated the trends in different characteristics of precipitation in Iran, the trends in precipitation indicators related to bioclimate are still not explored. The 0.5° spatial resolution gauge-based gridded monthly precipitation data of global precipitation climatology centre (GPCC) for the period 1901–2016 was used in this study for the evaluation of the geographical distribution of the trends of bioclimatic precipitation indicators of Iran. The trends in the indicators due to global warming were estimated using modified Mann-Kendall (MMK) trend test which can estimate unidirectional trend by separating the natural variability in climate. Obtained results were compared with that found using classical Mann-Kendall (MK) test. Besides, gridded temperature data of climate research unit (CRU) was used to identify the warm/cold periods at each grid point to assess the trends in precipitation during warm/cold periods, considering a wide spatial variation in the onset time of different seasons in Iran. The results revealed that many of the trends in some of the precipitation indicators obtained in earlier studies were due to natural fluctuation of climate. Annual precipitation in Iran was found decreasing only in the northwest semi-arid region at a rate of − 12.1 to − 14.05 mm/decade, while the precipitation in the wettest month was found increasing in a large area in the southwest semi-arid region at a rate of 3.1 to 5.3 mm/decade. The most significant changes were observed in precipitation seasonality, which was found to increase in 22.4% area, mostly in the central dry and northeast semi-dry regions and decrease in 11.3% area, mostly in the northern wetter region. The study indicates that the long-term natural variability in large-scale atmospheric phenomena that influences the precipitation of Iran may be the cause of many significant changes observed in precipitation in previous studies.
Sahar Hadi Pour; Ahmad Khairi Abd Wahab; Shamsuddin Shahid. Spatiotemporal changes in precipitation indicators related to bioclimate in Iran. Theoretical and Applied Climatology 2020, 141, 99 -115.
AMA StyleSahar Hadi Pour, Ahmad Khairi Abd Wahab, Shamsuddin Shahid. Spatiotemporal changes in precipitation indicators related to bioclimate in Iran. Theoretical and Applied Climatology. 2020; 141 (1-2):99-115.
Chicago/Turabian StyleSahar Hadi Pour; Ahmad Khairi Abd Wahab; Shamsuddin Shahid. 2020. "Spatiotemporal changes in precipitation indicators related to bioclimate in Iran." Theoretical and Applied Climatology 141, no. 1-2: 99-115.
Reliable prediction of rainfall extremes is vital for disaster management, particularly in the context of increasing rainfall extremes due to global climate change. Physical-empirical models have been developed in this study using three widely used Machine Learning (ML) methods namely, Support Vector Machines (SVM), Random Forests (RF), Bayesian Artificial Neural Networks (BANN) for the prediction of rainfall and rainfall related extremes during Northeast Monsoon (NEM) in Peninsular Malaysia from synoptic predictors. The gridded daily rainfall data of Asian Precipitation—Highly Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE) was used to estimate four rainfall indices namely, rainfall amount, average rainfall intensity, days having >95-th percentile rainfall, and total number of dry days in Peninsular Malaysia during NEM for the period 1951–2015. The National Centers for Environmental Prediction (NCEP) reanalysis sea level pressure (SLP) data was used for the prediction of rainfall indices with different lead periods. The recursive feature elimination (RFE) method was used to select the SLP at different NCEP grid points which were found significantly correlated with NEM rainfall indices. The results showed superior performance of BANN among the ML models with normalised root mean square error of 0.04–0.14, Nash-Sutcliff Efficiency of 0.98–1.0, and modified agreement index of 0.97–0.99 and Kling-Gupta efficient index 0.65–0.96 for one-month lead period prediction. The 95% confidence interval (CI) band for BANN was found narrower than the other ML models. Almost all the forecasted values by BANN were also found with 95% CI, and therefore, the p-factor and the r-factor for BANN in predicting rainfall indices were found in the range of 0.95–1.0 and 0.25–0.49 respectively. Application of BANN in prediction of rainfall indices with higher lead time was also found excellent. The synoptic pattern revealed that SLP over the north of South China Sea is the major driver of NEM rainfall and rainfall extremes in Peninsular Malaysia.
Sahar Hadi Pour; Ahmad Khairi Abd Wahab; Shamsuddin Shahid. Physical-empirical models for prediction of seasonal rainfall extremes of Peninsular Malaysia. Atmospheric Research 2019, 233, 104720 .
AMA StyleSahar Hadi Pour, Ahmad Khairi Abd Wahab, Shamsuddin Shahid. Physical-empirical models for prediction of seasonal rainfall extremes of Peninsular Malaysia. Atmospheric Research. 2019; 233 ():104720.
Chicago/Turabian StyleSahar Hadi Pour; Ahmad Khairi Abd Wahab; Shamsuddin Shahid. 2019. "Physical-empirical models for prediction of seasonal rainfall extremes of Peninsular Malaysia." Atmospheric Research 233, no. : 104720.
The spatial and temporal changes in annual and seasonal aridity, the shift of land from one arid class to another and the effect of this shift on different landuses in Iran during 1951–2016 have been assessed in this study. The monthly rainfall data of global precipitation climatology center (GPCC), and the monthly mean temperature and potential evapotranspiration (PET) data of climate research unit (CRU) having a spatial resolution of 0.5° were used for this purpose. The novelty of the study is the assessment of the significance in the shift of arid land between 1951 and 1980 and 1987–2016. Besides, the association of rainfall and temperature with aridity in different arid zones were assessed to understand the driving factors of the shift of arid lands. The results revealed an increase in annual and seasonal aridity in Iran, which caused expansion of arid land. The most remarkable changes include conversion of 4.84% semi-arid land to arid land due to an increase in annual aridity, shift of 4.84% arid land to hyper-arid during summer and 6.45% semi-arid land to arid during winter. However, only the expansion of semi-arid land to dry-subhumid land was found statistically significant. Analysis of results revealed different contributions of rainfall and temperature in the expansion of different classes of arid lands. The decrease in rainfall was the cause of the increasing aridity in the arid and semi-arid region, while the increasing temperature was found to play a major role in increasing aridity in the humid region. The overlapping of landuse map on aridity shift map revealed that the rangelands and farmlands in the north and the northwest were more affected by the expansion of aridity which might have severe consequences on agricultural production and food security of the country.
Sahar Hadi Pour; Ahmad Khairi Abd Wahab; Shamsuddin Shahid. Spatiotemporal changes in aridity and the shift of drylands in Iran. Atmospheric Research 2019, 233, 104704 .
AMA StyleSahar Hadi Pour, Ahmad Khairi Abd Wahab, Shamsuddin Shahid. Spatiotemporal changes in aridity and the shift of drylands in Iran. Atmospheric Research. 2019; 233 ():104704.
Chicago/Turabian StyleSahar Hadi Pour; Ahmad Khairi Abd Wahab; Shamsuddin Shahid. 2019. "Spatiotemporal changes in aridity and the shift of drylands in Iran." Atmospheric Research 233, no. : 104704.
Changes in bioclimatic indicators can provide valuable information on how global warming induced climate change can affect humans, ecology and the environment. Trends in thermal bioclimatic indicators over the diverse climate of Iran were assessed in this study to comprehend their spatio-temporal changes in different climates. The gridded temperature data of Princeton Global Meteorological Forcing with a spatial resolution of 0.25° and temporal extent of 1948–2010 was used for this purpose. Autocorrelation and wavelets analyses were conducted to assess the presence of self-similarity and cycles in the data series. The modified version of the Mann–Kendall (MMK) test was employed to estimate unidirectional trends in 11 thermal bioclimatic indicators through removing the influence of natural cycles on trend significance. A large decrease in the number of grid points showing significant trends was noticed for the MMK in respect to the classical Mann–Kendall (MK) test which indicates that the natural variability of the climate should be taken into consideration in bioclimatic trend analyses in Iran. The unidirectional trends obtained using the MMK test revealed changes in almost all of the bioclimatic indicators in different parts of Iran, which indicates rising temperature have significantly affected the bioclimate of the country. The semi-dry region along the Persian Gulf in the south and mountainous region in the northeast were found to be more affected in terms of the changes in a number of bioclimatic indicators.
Sahar Hadi Pour; Ahmad Abd Wahab; Shamsuddin Shahid; Xiaojun Wang. Spatial Pattern of the Unidirectional Trends in Thermal Bioclimatic Indicators in Iran. Sustainability 2019, 11, 2287 .
AMA StyleSahar Hadi Pour, Ahmad Abd Wahab, Shamsuddin Shahid, Xiaojun Wang. Spatial Pattern of the Unidirectional Trends in Thermal Bioclimatic Indicators in Iran. Sustainability. 2019; 11 (8):2287.
Chicago/Turabian StyleSahar Hadi Pour; Ahmad Abd Wahab; Shamsuddin Shahid; Xiaojun Wang. 2019. "Spatial Pattern of the Unidirectional Trends in Thermal Bioclimatic Indicators in Iran." Sustainability 11, no. 8: 2287.
Land Use/Land Cover (LULC) is essential in planning and management activities especially for conserving eco-environment, soil and vegetation research as well as urban planning. Higher resolution imagery and accuracy of LULC for monitoring ecosystem survival are preferred especially when it takes into account environmental issues. Langkawi had faced problems related to environmental issues after it has been designated as a geopark. Therefore, this study aims to map and evaluate digital classification methods of mapping of LULC using Very High Resolution (VHR) Quickbird satellite imagery in one of the Langkawi UNESCO Global Geopark, that is Kilim Karst Geoforest Park (KKGP) which is located at northeast of Langkawi, Kedah, Malaysia. Object-based and pixel-based classification methods were explored and compared. Object-based method involved multi-resolution segmentation part where scale parameter, shape and compactness should be assigned as accurate as possible, so that the image is segmented to homogenous area. Both segmentation and classification processes were conducted in e-Cognition software. While, a supervised classification, Maximum Likelihood Classification (MLC) involved selection of training areas was used for pixel-based method using ERDAS Imagine software. Then, classification accuracies were assessed by comparing both techniques using error matric and Kappa coefficient. The results from the classified image shows that the object-based approach provides more accurate results with an overall accuracy of approximately 87.91% and Kappa coefficient of 0.85 compared to the results achieved by MLC pixel-based classification with 72.21 % accuracy and Kappa coefficient of 0.66. As a conclusion, the results indicated that object-based technique has more advantages to be applied with VHR imagery for better environmental management and conservation actions.
M K A Halim; A Ahmad; M Z A Rahman; Z M Amin; M F A Khanan; I A Musliman; W H W Kadir; M H Jamal; D S Maimunah; Ahmad Khairi Abd Wahab; Muhammad Mun'Im Zabidi; N M Suaib; R M Zain. Land use/land cover mapping for conservation of UNESCO Global Geopark using object and pixel-based approaches. IOP Conference Series: Earth and Environmental Science 2018, 169, 012075 .
AMA StyleM K A Halim, A Ahmad, M Z A Rahman, Z M Amin, M F A Khanan, I A Musliman, W H W Kadir, M H Jamal, D S Maimunah, Ahmad Khairi Abd Wahab, Muhammad Mun'Im Zabidi, N M Suaib, R M Zain. Land use/land cover mapping for conservation of UNESCO Global Geopark using object and pixel-based approaches. IOP Conference Series: Earth and Environmental Science. 2018; 169 (1):012075.
Chicago/Turabian StyleM K A Halim; A Ahmad; M Z A Rahman; Z M Amin; M F A Khanan; I A Musliman; W H W Kadir; M H Jamal; D S Maimunah; Ahmad Khairi Abd Wahab; Muhammad Mun'Im Zabidi; N M Suaib; R M Zain. 2018. "Land use/land cover mapping for conservation of UNESCO Global Geopark using object and pixel-based approaches." IOP Conference Series: Earth and Environmental Science 169, no. 1: 012075.
Soheil Saeed Far; Ahmad Khairi Abd Wahab; Sobri Bin Harun. Determination of Significant Wave Height Offshore of the Federal Territory of Labuan (Malaysia) Using Generalized Pareto Distribution Method. Journal of Coastal Research 2018, 344, 892 -899.
AMA StyleSoheil Saeed Far, Ahmad Khairi Abd Wahab, Sobri Bin Harun. Determination of Significant Wave Height Offshore of the Federal Territory of Labuan (Malaysia) Using Generalized Pareto Distribution Method. Journal of Coastal Research. 2018; 344 ():892-899.
Chicago/Turabian StyleSoheil Saeed Far; Ahmad Khairi Abd Wahab; Sobri Bin Harun. 2018. "Determination of Significant Wave Height Offshore of the Federal Territory of Labuan (Malaysia) Using Generalized Pareto Distribution Method." Journal of Coastal Research 344, no. : 892-899.
Embankments are important infrastructure built to provide flood control. They also present risks to property and life due to their potential to fail and cause catastrophic flooding. To mitigate these risks, authorities and regulators need to carefully analyse and inspect dams to identify potential failure modes and protect against them. This paper presents morphology of an embankment study and its sediment behaviour of different grain sizes after the embankment fails. A few experiments were carried out for the embankment size of 1V:3H with different sediment grain sizes; medium and coarser sand. The embankment material used is non-cohesive soil with the embankment height of 0.1 m. The embankment is tested with inflows rate of Q = 0.8 L/s. Experimental results showed the peak discharge for the same inflow rate is affected by the shape of embankment breached. The peak discharge of medium grain size of the embankment is highest, which gave 3.63 L/s in comparison with a coarser embankment. This concludes that the embankment morphology patterns are dissimilar to each other. The flow and dimension of embankment are shown to influence the characteristics of embankment failure.
Z M Yusof; A K A Wahab; Z Ismail; Shahabuddin Amerudin. Characteristics of Non-Cohesive Embankment Failure. IOP Conference Series: Earth and Environmental Science 2018, 140, 012044 .
AMA StyleZ M Yusof, A K A Wahab, Z Ismail, Shahabuddin Amerudin. Characteristics of Non-Cohesive Embankment Failure. IOP Conference Series: Earth and Environmental Science. 2018; 140 (1):012044.
Chicago/Turabian StyleZ M Yusof; A K A Wahab; Z Ismail; Shahabuddin Amerudin. 2018. "Characteristics of Non-Cohesive Embankment Failure." IOP Conference Series: Earth and Environmental Science 140, no. 1: 012044.
A Wahab; D Ishak; M Jamal; Noor Zawawi. Coastal vulnerability index at a RAMSAR site: A case study of Kukup mangrove island. Civil, Offshore and Environmental Engineering 2016, 9 -13.
AMA StyleA Wahab, D Ishak, M Jamal, Noor Zawawi. Coastal vulnerability index at a RAMSAR site: A case study of Kukup mangrove island. Civil, Offshore and Environmental Engineering. 2016; ():9-13.
Chicago/Turabian StyleA Wahab; D Ishak; M Jamal; Noor Zawawi. 2016. "Coastal vulnerability index at a RAMSAR site: A case study of Kukup mangrove island." Civil, Offshore and Environmental Engineering , no. : 9-13.
Roberto Mayerle; Rangaswami Narayanan; Talal Etri; Ahmad Khairi Abd Wahab. A case study of sediment transport in the Paranagua Estuary Complex in Brazil. Ocean Engineering 2015, 106, 161 -174.
AMA StyleRoberto Mayerle, Rangaswami Narayanan, Talal Etri, Ahmad Khairi Abd Wahab. A case study of sediment transport in the Paranagua Estuary Complex in Brazil. Ocean Engineering. 2015; 106 ():161-174.
Chicago/Turabian StyleRoberto Mayerle; Rangaswami Narayanan; Talal Etri; Ahmad Khairi Abd Wahab. 2015. "A case study of sediment transport in the Paranagua Estuary Complex in Brazil." Ocean Engineering 106, no. : 161-174.
Little is known about the salt intrusion behaviour in Malaysian estuaries. Study of salt intrusion generally requires large amounts of data, especially if 2-D or 3-D numerical models are used; thus, in data-poor environments, 1-D analytical models are more appropriate. A fully analytical 1-D salt intrusion model, which is simple to implement and requires minimal data, was tested in six previously unsurveyed Malaysian estuaries (Kurau, Perak, Bernam, Selangor, Muar and Endau). The required data can be collected during a single day of observations. Site measurements were conducted during the dry season (June–August 2012 and February–March 2013) near spring tide. Data on cross-sections (by echo-sounding), water levels (by pressure loggers) and salinity (by moving boat) were collected as model input. A good fit was demonstrated between the simulated and observed salinity distribution for all six estuaries. Additionally, the two calibration parameters (the Van der Burgh coefficient and the boundary condition for the dispersion) were compared with the existing predictive equations. Since gauging stations were only present in some nested catchments in the drainage basins, the river discharge had to be up-scaled to represent the total discharge contribution of the catchments. However, the correspondence between the calibration coefficients and the predictive equations was good, particularly in view of the uncertainty in the river discharge data used. This confirms that the predictive salt intrusion model is valid for the cases studied in Malaysia. The model provides a reliable, predictive tool, which the water authority of Malaysia can use for making decisions on water abstraction or dredging
Jacqueline Isabella Gisen; Hubert H. G. Savenije; Remko C. Nijzink; Ahmad Khairi Abd Wahab. Testing a 1-D analytical salt intrusion model and its predictive equations in Malaysian estuaries. Hydrological Sciences Journal 2014, 60, 156 -172.
AMA StyleJacqueline Isabella Gisen, Hubert H. G. Savenije, Remko C. Nijzink, Ahmad Khairi Abd Wahab. Testing a 1-D analytical salt intrusion model and its predictive equations in Malaysian estuaries. Hydrological Sciences Journal. 2014; 60 (1):156-172.
Chicago/Turabian StyleJacqueline Isabella Gisen; Hubert H. G. Savenije; Remko C. Nijzink; Ahmad Khairi Abd Wahab. 2014. "Testing a 1-D analytical salt intrusion model and its predictive equations in Malaysian estuaries." Hydrological Sciences Journal 60, no. 1: 156-172.
Norasman Othman; Ahmad Khairi Abd Wahab; Mohamad Hidayat Jamal. EFFECTS OF SEASONAL VARIATIONS ON SANDY BEACH GROUNDWATER TABLE AND SWASH ZONE SEDIMENT TRANSPORT. Coastal Engineering Proceedings 2014, 1, 59 .
AMA StyleNorasman Othman, Ahmad Khairi Abd Wahab, Mohamad Hidayat Jamal. EFFECTS OF SEASONAL VARIATIONS ON SANDY BEACH GROUNDWATER TABLE AND SWASH ZONE SEDIMENT TRANSPORT. Coastal Engineering Proceedings. 2014; 1 (34):59.
Chicago/Turabian StyleNorasman Othman; Ahmad Khairi Abd Wahab; Mohamad Hidayat Jamal. 2014. "EFFECTS OF SEASONAL VARIATIONS ON SANDY BEACH GROUNDWATER TABLE AND SWASH ZONE SEDIMENT TRANSPORT." Coastal Engineering Proceedings 1, no. 34: 59.
In Malaysia, rainfall distribution patterns are normally influenced by seasonal wind flow patterns coupled with local topographic features. Heavy rain spells and storms during the Northeast Monsoon will affect groundwater table elevation and the beach profile. The aim of this paper is to investigate the relationship between rainfall and groundwater elevation and their effect to beach profile change. This work was undertaken at the Desaru Beach, Johor. The rainfall, groundwater table, tides and beach profiles data were measured at the site. As a result, the findings revealed that the groundwater table is affected by rainfall intensity; higher during wet season and lower during dry season. Groundwater table near the coastline is also affected by the tides. However, the data showed that there is a lag time between rising and falling of groundwater table and tides. Finally, the beach profile was found to be eroded as the groundwater elevation increased on the beach.
Ahmad Khairi Abd. Wahab; Norasman Othman; Mohamad Hidayat Jamal; Shairul Rohaziawati Samat. Effect of Rainfall and Groundwater Level on Sandy Beach Profile. Applied Mechanics and Materials 2014, 567, 32 -37.
AMA StyleAhmad Khairi Abd. Wahab, Norasman Othman, Mohamad Hidayat Jamal, Shairul Rohaziawati Samat. Effect of Rainfall and Groundwater Level on Sandy Beach Profile. Applied Mechanics and Materials. 2014; 567 ():32-37.
Chicago/Turabian StyleAhmad Khairi Abd. Wahab; Norasman Othman; Mohamad Hidayat Jamal; Shairul Rohaziawati Samat. 2014. "Effect of Rainfall and Groundwater Level on Sandy Beach Profile." Applied Mechanics and Materials 567, no. : 32-37.
Transfer function models of the rainfall–runoff relationship with various complexities are developed to investigate the hydrological behaviour of a tropical peat catchment that has undergone continuous drainage for a long time. The study reveals that a linear transfer function model of order one and noise term of ARIMA (1,0,0) best represents the monthly rainfall–runoff relationship of a drained peat catchment. The best-fitted transfer function model is capable of illustrating the cumulative hydrological effects of the catchment when subjected to drainage. Transfer function models of daily rainfall–runoff relationships for each year of the period 1983–1993 are also developed to decipher the changes in hydrological behaviour of the catchment due to drainage. The results show that the amount of rain water temporarily stored in the peat soil decreased and the catchment has become more responsive to rainfall over the study period. Editor Z.W. Kundzewicz; Associate editor D. Hughes Citation Katimon, A., Shahid, S., Abd Wahab, A.K., and Shabri, A., 2013. Hydrological behaviour of a drained agricultural peat catchment in the tropics. 2: Time series transfer function modelling approach. Hydrological Sciences Journal, 58 (6), 1310–1325.
Ayob Katimon; Shamsuddin Shahid; Ahmad Khairi Abd Wahab; Ani Shabri. Hydrological behaviour of a drained agricultural peat catchment in the tropics. 2: Time series transfer function modelling approach. Hydrological Sciences Journal 2013, 58, 1310 -1325.
AMA StyleAyob Katimon, Shamsuddin Shahid, Ahmad Khairi Abd Wahab, Ani Shabri. Hydrological behaviour of a drained agricultural peat catchment in the tropics. 2: Time series transfer function modelling approach. Hydrological Sciences Journal. 2013; 58 (6):1310-1325.
Chicago/Turabian StyleAyob Katimon; Shamsuddin Shahid; Ahmad Khairi Abd Wahab; Ani Shabri. 2013. "Hydrological behaviour of a drained agricultural peat catchment in the tropics. 2: Time series transfer function modelling approach." Hydrological Sciences Journal 58, no. 6: 1310-1325.
Ayob Katimon; Shamsuddin Shahid; Ahmad Khairi Abd Wahab; Hazrat Ali. Hydrological behaviour of a drained agricultural peat catchment in the tropics. 1: Rainfall, runoff and water table relationships. Hydrological Sciences Journal 2013, 58, 1297 -1309.
AMA StyleAyob Katimon, Shamsuddin Shahid, Ahmad Khairi Abd Wahab, Hazrat Ali. Hydrological behaviour of a drained agricultural peat catchment in the tropics. 1: Rainfall, runoff and water table relationships. Hydrological Sciences Journal. 2013; 58 (6):1297-1309.
Chicago/Turabian StyleAyob Katimon; Shamsuddin Shahid; Ahmad Khairi Abd Wahab; Hazrat Ali. 2013. "Hydrological behaviour of a drained agricultural peat catchment in the tropics. 1: Rainfall, runoff and water table relationships." Hydrological Sciences Journal 58, no. 6: 1297-1309.
In this study, an Euler–Lagrange coupling two-phase flow model, namely movable bed simulator (MBS)-two-dimensional (2D) model was employed to explore the current-induced live-bed scour beneath marine pipelines. The fluid phase characteristics, such as velocity and pressure, were obtained by the Reynolds-averaged Navier–Stokes (RANS) equations with a k-ε turbulence closure model in a two-dimensional Eulerian grid, whereas the seabed beneath pipelines was traced as an assembly of discrete sand grains from the Lagrangian point of view. The live-bed scour was evolved as the motion of a granular media based on distinct element method (DEM) formulation, in which the frequent interparticle collision was described with a spring and dashpot system. The fluid flow was coupled to the sediment phase, considering the acting drag forces between. Comparison between the numerical result and experimental measurement confirms that the numerical model successfully estimates the bed profile and flow velocity field. It is evident that the fluid shear stress decreases with the increasing of gap ratio e/D. The numerical model provides a useful approach to improve mechanistic understanding of hydrodynamic and sediment transport in live-bed scour beneath a marine pipeline.
A. Yeganeh-Bakhtiary; M. Zanganeh; E. Kazemi; L. Cheng; A. K. Abd Wahab. Euler–Lagrange Two-Phase Model for Simulating Live-Bed Scour Beneath Marine Pipelines. Journal of Offshore Mechanics and Arctic Engineering 2013, 135, 031705 .
AMA StyleA. Yeganeh-Bakhtiary, M. Zanganeh, E. Kazemi, L. Cheng, A. K. Abd Wahab. Euler–Lagrange Two-Phase Model for Simulating Live-Bed Scour Beneath Marine Pipelines. Journal of Offshore Mechanics and Arctic Engineering. 2013; 135 (3):031705.
Chicago/Turabian StyleA. Yeganeh-Bakhtiary; M. Zanganeh; E. Kazemi; L. Cheng; A. K. Abd Wahab. 2013. "Euler–Lagrange Two-Phase Model for Simulating Live-Bed Scour Beneath Marine Pipelines." Journal of Offshore Mechanics and Arctic Engineering 135, no. 3: 031705.
Morteza Zanganeh; Abbas Yeganeh-Bakhtiary; Ahmad Khairi Abd Wahab. Lagrangian coupling two-phase flow model to simulate current-induced scour beneath marine pipelines. Applied Ocean Research 2012, 38, 64 -73.
AMA StyleMorteza Zanganeh, Abbas Yeganeh-Bakhtiary, Ahmad Khairi Abd Wahab. Lagrangian coupling two-phase flow model to simulate current-induced scour beneath marine pipelines. Applied Ocean Research. 2012; 38 ():64-73.
Chicago/Turabian StyleMorteza Zanganeh; Abbas Yeganeh-Bakhtiary; Ahmad Khairi Abd Wahab. 2012. "Lagrangian coupling two-phase flow model to simulate current-induced scour beneath marine pipelines." Applied Ocean Research 38, no. : 64-73.