Pusat Penyelidikan Kejuruteraan Sungai dan Saliran Bandar (REDAC) - Tesis

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Assessing sustainability index of water resources system for lombok river basin
(2022-05-01)
Wit Saputra, Anggara Wiyono
River basin sustainability is vital for the fulfilment of water demands, but the majority of river basins worldwide, including those in Indonesia, are increasingly being severely degraded, leading to their unsustainability. The Lombok river basin at Nusa Tenggara Barat province, Indonesia, is currently experiencing such problems. Water balance in the Lombok river basin is closely affected by climate conditions, which in turn affects the availability of water. In addition, the basin is experiencing shrinking reservoir storage due to sedimentation, deterioration of river headworks structure, and irrigation efficiency reduction, all of which have a reverse effect on maintaining the sustainability of the water resources system. This study focuses on the Lombok river basin, which experiences unique climate characteristics and conditions in variability which has generally affected water availability and its distribution. Interbasin transfer conveys water from the western area, which has surplus water, to the central and eastern parts of the river basin. This study aims to assess the water resources system sustainability in light of the availability of streamflow and fulfilment of water demand in the Lombok river basin to provide information for the stakeholders and decision-makers. The methodology includes simulation and optimization of the water resources system to assess the water resource system performance indicators (reliability, resilience, and vulnerability) and sustainability index for various system improvement scenarios. The SWAT model was employed to simulate the Lombok streamflow with the corresponding land use and soil map data based on historical data as the required inputs. Calibration and validation processes using SUFI-2 were done to get the appropriate parameters used in SWAT model. By applying simulated streamflow as an input, the MODSIM model was used to simulate and optimize water allocation in the system to predict performance indicators at each headwork for irrigation and domestic demand. The results show that the smallest watershed sustainability index for irrigation was in the Renggung watershed and the Palung watershed was the smallest domestic watershed sustainability. The results show that the smallest watershed sustainability index for irrigation was in the Renggung watershed at 0.188 in 2017-2025, which decreased to 0.177 in the climate change period (2032-2040). Babak watershed was the smallest domestic watershed sustainability index at 0.884 and down to 0.812 in the climate change period. Watershed index with the same weight of 0.50 for domestic and irrigation demand, respectively, showed the highest was Jangkok watershed followed by Dodokan, Meninting-Midang, Renggung, Babak, Palung, Rere Penembem, and Pare Ganti. Results from this study indicated that the operation of the new dams and improvement of irrigation efficiency enhanced the water sustainability index at most simulation scenarios. These results indicate that careful constructing of suitable new dams and improvement of irrigation efficiency is justified in the Lombok river basin as they contribute towards the enhancement of water sustainability in the river basin.
Numerical simulation of hydraulic jump using depth-averaged model
(2022-08-01)
Ting, Wen Kiat
The prediction of the location, flow profile and length of hydraulic jump is crucial in the design of hydraulic structure such as stilling basin. For such purposes, numerical model comes in handy and is more cost-efficient as compared to physical modelling. In this study, two governing equations (Saint-Venant (SV) equations and Boussinesq equations) were solved numerically using four numerical algorithms (the Upwind, MUSCL+AB, CIP+SMAC, and CIP/ MM FVM) to simulate the formation of hydraulic jump in a flat rectangular channel. In the model verification process, simulation of dam-break flow problem was carried out. In the model verification process, the CIP+SMAC algorithm showed the best agreement against Ritter solution whilst the CIP/ MM FVM model was well verified against the Stoker’s solution. The numerical models were validated by simulating the one-dimensional hydraulic jump problem. The numerical results were validated against the experimental data. The experiment data were obtained from literature findings and also from the physical experiment conducted at the REDAC Hydraulic Laboratory, USM. Results showed that the Boussinesq equations are better than the SV equations in simulating hydraulic jump. Through qualitative evaluation, the CIP+SMAC algorithm showed the best performance as compared to the Upwind and MUSCL+AB algorithms. Besides, an attempt to simulate the hydraulic jump using the CIP/MM FVM scheme was carried out. Hydraulic jump was successfully simulated using this scheme, with the highest inflow Froude number of 2.3. However, simulation cases with inflow Froude number higher than Fr=2.3 could not be simulated due to numerical instability. Further investigation and model improvement are needed to solve this problem in the future.
Decision-making framework with theapplication of cost benefit analysisfor flood mitigation measures
(2023-03-01)
Zuriyati Binti Yusof
Flood scenarios often have negative impacts on economic activity and the economic activity will be paralyzed if the flood phenomenon is not dealt clearly, effectively and consistently. Past studies have highlighted that the hydrodynamic modelling used in engineering analysis is the tool used to evaluate flood protection under current conditions and with mitigation plans. Therefore, flood protection has always received considerable attention, resulting in significant flood protection investment. In order to balance up the need between the society and the environment, it is crucial for the decision maker to comprehend that every alternative available has an opportunity cost. Concerning that, as to pertain sustainable development, it is important to examine the costs and benefits of an investment involving the flood management. This study recommends that, flood engineering analysis to be conducted along with Cost Benefit Analysis (CBA) to evaluate the effectiveness of the flood mitigation project in terms of finance, social and environmental impact. The purpose of CBA is to determine the reliability of any investment opportunity and provide fundamentals for making comparisons with other flood mitigation proposals. The main contribution of the study is therefore to facilitate the decision-making process for flood mitigation project implementation more efficient and effective. In order to achieve the research objectives, mixed method of both quantitative and qualitative evaluation were carried out. The evaluated engineering analysis through hydrodynamic modelling will therefore be the main input for the decision-making process that looks into the cost and benefit of it. CBA performed for flood mitigation measures of river improvement and flood wall provides the B/C ratio of 1.00 is a beneficial project when the benefits outweigh the costs and generate an increase in economic welfare. Therefore, it shows how CBA is quantified by the social advantages and disadvantages of alternative options in terms of a common monetary valuation. The study provides a basic understanding of CBA as the decision-making tools, despites the constraints and limitations of quantifying the flood protection strategy in monetary terms. CBA is also helpful in planning efficiently and strategically especially when resources are limited. This study also demonstrates that when combined with economic analysis, engineering analysis can provide rational information for the decision-making process as a whole in the flood management decision-making framework.
Modelling of biochemical oxygen demand, chemical oxygen demand and ammoniacal nitrogen for sungai perai basin using hydrodynamic model
(2023-05-01)
Danial Nakhaie Bin Mohd Souhkri
Shortage of clean water has been an issue for an urbanised areas. To overcome the problem, Pulau Pinang tries to find an alternative source of water; and one of the options is Sungai Perai. The river has a large catchment area and is located in Pulau Pinang state boundary however the river was polluted and not suitable to be extracted for domestic consumption. To understand the behaviour of the river, a water quality model was developed for Sungai Perai, Sungai Jarak and Sungai Kulim using InfoWork ICM. Rainfall data and topographical information were use for hydrological analysis; while sampling and demographical information as pollution input for the water quality model. Year 2016 was selected as model event due to data availability. The result of three parameters (BOD, COD and NH4) was used for analysis and TMDL calculation; load duration curve approach was used to estimate TMDL. Based on the analysis, it was observed the concentration of pollutants is highest in March and lowest in November. The concentration was observed to be in relation to seasonal change; as the flow increased, the concentration decreased. The simulation data was used to generate TMDL. It was discovered that pollutant load exceedance about 95% which is the highest during the rainy season and the problematic pollutant is NH4.
Tropical plants performance in urban runoff treatment using bioretention system
(2023-06-01)
Poovarasu Jhonson
Bioretention systems are among the most popular stormwater best management practices (BMPs) for urban runoff treatment. Studies on the plant performance using bioretention systems have been conducted, especially in developed countries with a temperate climate, such as the United States and Australia. The objectives of this research is to examine the performance and efficiency of tropical plants in removing the pollutants from the runoff and to determine the optimum hydraulic retention time for the plant to achieve the best efficiency in bioretention system. This study was divided into 2 phases, Phase 1 involved urban runoff characterization whereas Phase 2 covers plant mesocosm study. Phase 2 was further divided into 2 (Phase 2a and Phase 2b); Phase 2a focuses on the performance of tropical plants in treating urban runoff polluted with greywater using bioretention system and subsequently five best plant species were chosen to be used in bioretention applications. Phase 2b study focuses on the performance of bioretention system under different hydraulic retention time (HRT) under tropical climate. The same plants were tested under greenhouse environment with three different HRTs. Ten different tropical plant species were triplicated and planted in 30 mesocosms with two control mesocosms without vegetation. One-way ANOVA was used to analyse the performance of plants, which were then ranked based on their performance in removing pollutants using the total score obtained for each water quality tests for Phase 2a, whereas for Phase 2b one-way ANOVA together with Tukey HSD test was used to study the significant difference between different HRT and plant species in removing pollutants. For Phase 2a, results showed that vetiver topped the table with 86.4% of total nitrogen (TN) removal, 93.5% of total phosphorus (TP) removal, 89.8% of biological oxygen demand (BOD) removal, 90% of total suspended solids (TSS) removal and 92.5% of chemical oxygen demand (COD) removal followed by blue porterweed, hibiscus, golden trumpet and tall sedge. As for Phase 2b, results showed that 48 hours of HRT had better influence in COD, TN and TSS removal (95.4%, 93.1% and 87.3% respectively) using vegetated bioretention system, unlike TP where its removal was at its best in 24 hours of HRT. 48 hours of HRT is viable and ideal to be practiced in bioretention system. This research concluded that vetiver, blue porterweed, hibiscus, golden trumpet and tall sedge are suitable to be used in bioretention system alongside with 48 hours of hydraulic retention time to get the best out of bioretention system in tropical region.
The design and economic feasibility of individual on-farm pond (i-ofp) for supplementary irrigation in paddy field
(2024-01-01)
Nadiatul Amira, Ab Ghani
This study proposes the individual on-farm pond (i-OFP) as a solution to overcome the irrigation water shortage problem in the paddy field. A methodology to design the i-OFP for additional irrigation is established, and its economic feasibility is studied. The i-OFP is used to collect and store the return flow from the paddy field, and the water is utilized during dry season. To establish the methodology, field data such as inflow discharge into the paddy field during the main and off-season inflow water depth at the irrigation channel was collected. By applying the principle of mass conservation, a simple water balance model is built to estimate the maximum amount of return flow from the paddy field during field flooding. The return flow was utilized to design the individual on-farm pond (i-OFP), and both the inlet and outlet flow control structures. During high water demand and dry period, the return flow collected and stored in i-OFP will be used for additional irrigation. Furthermore, the economic feasibility of the i-OFP system is assessed by using the present value (PV) method. The study's findings revealed that a simple methodology may be used to build an i-OFP for water reuse and additional irrigation. According to the economic feasibility analysis results, the i-OFP system might generate a positive economic return if the initial construction and maintenance costs of the system are fully subsidized. Results from the study may be used as a guide for the construction of on-farm ponds and provide insights into the economic feasibility of i-OFP.
Assessing the effects of vegetation, influent concentration, and design sizing in establishment of pollutant reduction perfomance curve for bioretention system
(2024-02-01)
Woon, Khee Ling
Bioretention is one of stormwater best management practices (BMPs) that can treat water quantity and quality effectively. However, there is still a lack of studies regarding the effectiveness of bioretention in treating stormwater in a tropical context. Both experimental study and modelling were conducted to address the literature gap in bioretention research within a tropical context. One of the objectives of this study is to evaluate the hydrology and pollutant removal performance with the changes in planting conditions. A pilot-scale bioretention site was constructed in Universiti Sains Malaysia (USM), Engineering Campus with three plots: plot without vegetation (P1), single species (P2) and multispecies with tropical plants (P3). In Stage 1 experiment, the performance of bioretention was evaluated based on peak flow (Qpeak) reduction, pollutant outlet concentration and pollutant removal efficiency. P3 showed the best result in Qpeak reduction with 82%, followed by P2 (78.2%) and P1 (75.4%). The presence of vegetation improves the pollutants removal efficiency, especially total suspended solids (TSS) and total nitrogen (TN), with removal efficiency up to 95% and 85% respectively. For pollutant outlet concentration, bioretention with multispecies plants (P3) can treat TSS and chemical oxygen demand (COD) up to class II, based on the water quality index (WQI) classification. The result reflected that the plant diversity is important in bioretention systems as it showed better performance. Overall, the influent concentration showed positive correlation to pollutant removal (except COD and BOD). Stage 2 experiment was conducted to assess the effect of bioretention sizing on bioretention performance. As a result, the increase of incoming water promoted more exfiltration and affected the Qpeak at outlet with the increase of 22%, 14% and 0.3% for P1, P2 and P3 respectively. To achieve the third objective, bioretention model using MUSIC X was calibrated and validated based on the experiment data. For water quantity prediction, the model was evaluated based on Nash-Sutcliffe Efficiency (NSE), which has achieved 0.713 and 0.938 for the calibrated and validated model respectively. The performance rating for prediction of TSS, TN and TP removal based on percentage bias was ‘very good’ after the calibration of k-C* model in MUSIC X. Lastly, a pollutant reduction performance curve was established up to 5% of bioretention area to the impervious catchment area. This study provides insight regarding the importance of multispecies planting, proper sizing, and pollutant reduction performance curve establishment for the effective implementation of bioretention systems.
Efficiency study of preliminary and primary wastewater treatment system using computational fluid dynamics
(2024-09)
Purany a/p Kalimuthu
Preliminary and primary treatment studies are both crucial in the first stage of wastewater treatment plants (WWTPs). Computational Fluid dynamics (CFD) was used to model and simulate the hydrodynamic behaviors and solid settling of preliminary and primary treatment in a physical operation unit. The CFD model can predict flow dynamics in secondary screening tank, grit and grease chamber and sedimentation tank as well as solid deposition in the sedimentation tank. The 3D model was developed using ANSYS FLUENT 2022 R1 software with an Eulerian multiphase approach (air-water-sludge), Multi-Fluid VOF method, and SST k-𝜔 turbulent model with Navier-Stokes equations. The analysis examines water and solid velocity profiles, volume fractions, flow distributions, travel time from inlet to outlet, and tank characteristics. An analysis of the vector profile was conducted to investigate the flow characteristics within the tanks and chamber. The numerical simulation results were validated against experimental data, showing relative errors of 1.5 % for inlet velocity and 4.6 % for output velocity. The purpose of the research is to develop a Computational Fluid Dynamics (CFD) model to simulate the fluid dynamics, sedimentation tank solid distribution, and deposition. This simulation tool evaluates flow characteristics during the preliminary and primary treatment stages, offering insights to improve fluid behavior and process efficiency for future research work. This proposed Eulerian model can be a reference for future research works, and this model can be improved to produce a better water treatment plant.
Preparation, characterization and functional evaluation of agricultural waste-derived nanocelluloses
(2024-09-01)
Lim, Kah Yee
Nanocelluloses (NCs), the fundamental natural building block of cellulosic based fibres, have fore-fronted to be a new generation of functionalized materials, which have attracted tremendous attention in the nanotechnology community. Specifically, the functional roles of NCs represent the interplay between the surface compositions, crystalline structure, charge density, structural transitions, and their hydration/ dehydration behaviour, that give rise to different characteristics. In this work, the preparation of multifunctional nanocelluloses (NCs) from coffee residue (Coffea robusta L.) (CR), rice husk (Oryza sativa) (RH) and tangerine peel (Citrus unshiu) (TP) via three major synthesis techniques, notably hydrothermal, microwave and enzymatic hydrolysis synthesis approaches have been succeeded. The unique characteristics of NCs were evaluated with respect to the scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, zeta potential measurement, chemical composition, elemental analysis, surface charge and degree of substitution (DS). The adsorptive performance of NCs were examined by batch adsorption experiments using both cationic and anionic model adsorbates, methylene blue (MB) and chlorpyrifos (CPF), and simulated by the non-linear isotherm models. Their unique antimicrobial functions were tested against both gram-positive (Staphylococcus aureus and Bacillus subtilis) and gram-negative (Escherichia coli and Salmonella typhi) bacterial species using in-vitro colony-forming unit count method. The particle length and diameter, aspect ratio, crystallinity index, zeta potential, surface functional charge and DS of these newly prepared rod-shaped CR CNCs, whisker-shaped RH-CNWs and entangled microfiber network TP-CNFs were identified to be 264.35-649.97 nm, 22.07-25.26 nm, 10.47-29.46, 65.9-75.0 %, -30.2- -44.5 mV, 0.21-0.23 mmol/g and 0.135-0.148, respectively. The characteristic profiles of CR-CNCs, RH-CNWs and TP-CNFs displayed lattice crystallographic planes of cellulose Type-Iβ polymorphs, signifying the successive isolation of nano sized fragments from the matrix of amorphous and non-cellulosic materials. The equilibrium data were found to be in good agreement with the Langmuir isotherm model, with the monolayer adsorption capacities (Qo) for MB and CPF of 283.42- 429.51 mg/g and 98.29-192.99 mg/g, respectively. The adsorption process was driven mainly by the hydrogen bonding, electrostatic attraction, π-π and ion-dipole interactions, and the synergistic interplay of Lewis-base reaction and hydrophobic forces between model adsorbates with the functionalized NCs. Excellent inhibition efficiencies against both gram-positive S. aureus and B. subtilis and gram-negative E. coli and S. typhi have been detected, with the inhibition rates of 81-95 % for CR CNCs, 88-98 % for RH-CNWs and 72-93 % for TP-CNFs, respectively. The antibacterial actions marked the leakage of protein (4.47-42.90 µg/mL) and nucleic acid (0.68-16.25 µg/mL) from the bacterial cells. The unique features and multi functional roles of different NCs have been well-elucidated, which would allow an integral valorisation of currently undervalued biomass waste feedstock, and contribute to a “zero-waste” and “circular economic model”.

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