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

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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.
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.
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.
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.

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