Derivation of engineering design criteria for flow field around intake structure: A numerical simulation study

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

Field investigation of seasonal variations impact on flow depths and velocities in the swash zone

Most studies of the hydrodynamics and sediment transport in the swash zone in recent years have stressed the importance of swash processes in terms of science advancement and practical applications in this field of study. Clearly, the hydrodynamics of the swash zone are complex and not fully understood. The hydrodynamics of the swash zone characteristics likes swash water depth and velocity will affected the sediment transport mechanisms that mostly control beach face morphology especially under dry and wet periods in east coast region of Peninsular Malaysia. Field monitoring works at Desaru beach for data of rainfall distribution, morphological changes and swash characteristics likes flow depths and velocities have been conducted and analysed for both different periods (dry and wet). From observation, it is believed that rainfall distribution during the seasonal variation of dry and wet seasons in Malaysia affects the swash characteristics mainly by the infiltration processes in beach areas and significantly controlled the morphological changes in the swash zone

Analytical and statistical approaches to study the impacts of shoreline change towards mangroves at Kukup Island National Park, Johor

Shoreline and mangroves form a dynamic ecosystem to coastal area. They support and supply various foods and protections to ensure the sustainability of coastal ecosystem around the world. Despite these, information that exclusively emphasize on the interaction of shoreline change and mangroves on an island is still lacking, making assessment and observation towards coastal areas on island less significant. Hence, this study is significant to provide a first view of the interaction and the relationship and response of shorelines change towards mangrove physical characteristics. GIS, remote sensing as well as statistical analysis such as DSAS and linear regression were applied to support the study that consisted of three main stages which involve data collection, data processing and comparison of mangroves physical characteristics towards the changes in shoreline positions. Finding revealed that during the time span of 2005-2011, shoreline near to Sg Ular has experienced more erosion, resulted in the shoreline shifting that was ranged between -0.02 m/y and -1.52 m/y. Further analysis of shoreline change and mangroves physical characteristic unveiled that a significant relationship of mangrove characteristics and shoreline changes rates occurred at Sg Ular. It was found that mangroves communities along the shoreline of Sg Ular was negatively influenced by the shoreline change, possibly due to mild erosion along the shoreline towards the river mouth of Sg Ular

Testing a 1-D analytical salt intrusion model and its predictive equations in Malaysian estuaries

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

Integrasi kaedah geospatial dan pemodelan hidrodinamik untuk mengkaji impakkenaikan aras laut terhadap kawasan pantai

Kawasan pesisir pantai merupakan kawasan yang sangat terdedah dan sensitif kepada pelbagai ancaman terutamanya hakisan dan limpahan yang boleh menyebabkan impak negatif kepada kesejahteraan hidup manusia, persekitaran dan ekosistem. Kawasan pesisir pantai di Batu Pahat, Johor sangat terdedah kepada masalah banjir akibat fenomena air pasang dan sebahagian kawasan pantai lain dikategorikan sebagai kawasan hakisan pantai kritikal. Tujuan kajian ini adalah untuk mengenal pasti impak kenaikan aras laut terhadap komuniti pesisir pantai di Batu Pahat. Dengan menggunakan perisian ArcGIS dan MIKE21, kawasan banjir yang berlaku terhadap penempatan komuniti di pesisir pantai Batu Pahat dapat dikenal pasti dan meramalkan impak masa hadapan. Melalui hasil kajian, kawasan pantai di Batu Pahat mengalami kejadian hakisan pantai yang aktif dan jumlah kadar kehilangan tanah di kawasan tersebut sebanyak 415.7 hektar berbanding dengan kadar pemendapan yang hanya mendapat kira-kira 68.52 hektar. Hasil peta-peta risiko inundasi bagi kenaikan aras laut menunjukkan anggaran seramai 50 hingga 1145 populasi daripada jumlah penduduk seramai 28420 orang akan menerima impak kesan dari kenaikan aras laut pada tahun 2013, 2020 dan 2040. Selain itu, daripada 33 batang jalan raya di kawasan kajian, hanya 1 kawasan akan menghadapi kesan kenaikan aras laut pada tahun 2020 dan 2040. Justeru itu, peta risiko inundasi yang disediakan bagi pantai Batu Pahat amatlah berguna untuk mencegah hakisan pantai dan mengurangkan bencana masa depan

Coastal hydraulics modeling: model set up and data collection

The interaction of hydrodynamic forces in the coastal and estuarial areas is a complex phenomenon. It may however, be simulated using computer models. The use of numerical models helped in analysing and investigating hydrodynamic behaviour. This in tum facilitated the processes of design and decision making in coastal engineering design works. There are various types of computer model in use but for each application it is important to apply the correct model set-up to ensure optimum execution and reliable outputs. This paper introduces typical sample of such models with greater emphasis on tidal models. The practical aspects of setting up the model and data collection are presented. This is based on many years' experience of using and developing such model

Hydrological Analysis Of A Drained Peat Basin Using Time Series Correlation And Crosscorrelation Functions

A simple algebraic correlation and cross-spectral approach was applied to study the stream flow hydrograph of peat basin. The analysis involved the transformations of input variables (rainfall) and output variables (stream flow and water table). Analogous to the input-output signal in electronics, the peat aquifer is considered as a filtering system. The filter is able to transform, retain or eliminate the input variables (input signal) before the output variables (output signal) are created. The behaviour of flow through basin aquifer system is deduced from the degree of the transformation of the input signal. Several important aquifer parameters were deduced from the transformation process. They are the response time, the distinction between flows (quick-flows, intermediate flow or base-flow) and the delay. These hydrological parameters are required as design parameters for a water resource project within a basin-underlain peat soil aquifer

Hydrologic characteristics of a drained tropical peat catchment : runoff coefficients, water table and flow duration curves

Reclamation and drainage of peat basin is an important land development in Malaysia. A clear understanding on the hydrologic behavior of a drained peat basin is the essential factor towards an optimal management of the resource. Hydrological data from Madirono peat catchment located in Johor State, Malaysia was collected and used to characterise its hydrologic characteristics. The characterizations were made using the ordinary quantitative hydrologic approach. The magnitude of changes in the major hydrologic component of the study catchment was quantified. The study catchment experienced a large variation in runoff coefficient, indicating that a drained peat basin is a highly dynamic hydrologic system. A decaying trend in the annual runoff coefficient was observed. The annual runoff coefficients were large, ranging from 0.32 to 0.92. This indicates that the hydrology of the study catchment was extremely dynamics, highly permeable and very flashy. The low flow condition of the basin was extremely small but improving over time indicating that the basin could not sustain river flow during dry spell. The mean annual water table decreased over time by 2.7 cm per year

Effects of coastal development on ship manoeuvring and navigation

Coastal development, such as land reclamation or dredging, usually changes the characteristics of the coastal waterway. A common phenomena due to restricted waterway is increase in ship resistance and reduction in manoeuvrability. The restricted water inflow under the vessel, result in increased water velocity under the hull. The increase of the inflow velocity at the rudder may result in the increase of the rudder normal force or create partial vacuum in the region near propeller and rudder. Consequently, manoeuvring of ships may become erratic in this condition. Standard for ship maneuvrabiity have been developed by International Maritime Organization (IMO) to ensure safe navigation/ship handling operation of ships. The standards provide criteria on the ship turning ability, yaw checking ability, course keeping ability and stopping ability. Where there is uncertainty in the behavior of the vessel especially in restricted waters, the use of numerical simulation for evaluating navigational risks is highly depended upon. In this paper, firstly, the effects on water depths and currents due to coastal development will be described. Secondly, using time domain simulation approach, the manoeuvring characteristics of vessel in two scenarios, i.e. deep and shallow water are discussed. Thirdly, actual simulations demonstrating the risks involved in navigating in a restricted waterway will be demonstrate