Many cities in Vietnam are located at the coast and are exposed to heavy weather events that yearly causes casualties and economic losses. At the same time the country is developing rapidly and thus more space is allocated to accommodate urban growth. Studies have shown that there are cases in Vietnam were residential expansions have led to an increase in risk of pluvial flooding. This type of flooding is caused by insufficient capacity of the urban drainage system as a result of heavy rainfall.

Keeping in mind the exposure of flooding in Vietnam and the potential of SUDS to provide flood risk reduction, it is desirable to set general design guidelines with respect to urban drainage. On top of that, 1D/2D hydrodynamic models have proven to be useful when mapping flood risk at different scales. Therefore, this study aims to show how 1D/2D hydrodynamic models can be put into practice when designing drainage infrastructure and implementing flood adaptation measures. For this research, hydrodynamic modelling tool Delft 3D-FM (D-HYDRO) was implemented in the drainage design of Hà Nam island in Quang Ninh province.

This study provides predictions of pluvial flooding for the future development scenario of Hà Nam island. Based on the 2023 masterplan, all projected land use and terrain changes have been incorporated in the 1D/2D hydrodynamic model. Hà Nam island currently discharges it’s stormwater by means of sluice gates that can only be opened during low tide. Based on sea level rise predictions, it is estimated that the probability that Hà Nam receives rainfall during high tide will increase the coming decades. Therefore the urban drainage design considers extreme rainfall events during which the area can only be drained by means of pumping stations. Based on the modelling study, it is concluded that the existing residents of Hà Nam will face an increased risk of pluvial flooding in the future development scenario. This study proposes the implementation of two types of SUDS to increase local stormwater storage, namely vegetated swales and park overflow zones. It was found that these do result in flood risk reduction, but still leave current residents of Hà Nam vulnerable to flooding during extreme rain events. This study recommends making modifications to the 2023 masterplan, emphasizing the safety and wellbeing of Hà Nam residents.

The River Dommel is a modest-sized and ecologically sensitive stream located in the southern region of the Netherlands, covering a catchment area of 153,000 hectares. Its primary water source is rainwater, supplemented by a minor contribution from groundwater, particularly notable in the upstream portion of the catchment. Nevertheless, rainwater remains the primary source feeding the river, with its influence most pronounced in the midstream and downstream portions of the Dommel. In addition to that, the River Dommel receives the Eindhoven Wastewater Treatment Plant’s effluent while flowing through the city of Eindhoven. Eindhoven WWTP is one of the largest wastewater treatment facilities in the Netherlands with a 750,000 Population Equivalent (p.e.) and its effluent contributes approximately 50% of the total flow in the River Dommel during dry summer periods (Weijers et al., 2012; Kamstra, 2018).
During dry summer seasons, the Rivel Dommel faces the problem of insufficient base flow and low water levels due to decreased precipitations and increased evaporation rates. Insufficient base flow and therefore low water levels causes water quality issues in the River Dommel. Moreover, inadequate water flow, compounded by warmer temperatures in the summer, exerts stress on aquatic ecosystems within the River Dommel.
The primary objective of this report is to present a comprehensive study aimed at identifying a technically and economically viable solution to feed the River Dommel base flow during dry weather flow (DWF) conditions. Possible solutions addressing these challenges are elaborated and discussed in this report. Consequently, the application of sewer mining technology is chosen to be further investigated. The idea of implementing the sewer mining technology in this study is based on the extraction of the wastewater from Riool-Zuid sewer system, followed by cleaning processes and feeding the River Dommel with reclaimed water. While there are several treatment methods that can be applied in sewer mining, a thorough review of the literature, as presented in the relevant sections of this report, has led to the conclusion that a combination of Forward Osmosis (FO) and Reverse Osmosis (RO) represents an effective and efficient approach to achieving the objectives of this study. However, it should be noted that, implementation of sewer mining technology directly impacts current sewer system conditions and potentially give rise to significant challenges such as corrosion, odour and health impacts. Therefore, the impact of the sewer mining concept on the Riool-Zuid sewer system is also investigated and discussed in this study, followed by proper risk-mitigation measures.
The analysis of sewer mining is conducted through Mega-WATS simulations, based on a number of separate scenarios composed of three different implementation locations and various extraction ratios. The pressure main plays a crucial role on the extent of sewer mining technology impact on the Riool-Zuid sewer system as it represents anaerobic conditions while the rest of the sewer system is composed of gravity pipes representing aerobic conditions. Therefore, de Meren and Aalst are chosen to reveal the impact of anaerobic conditions on the severity of water extraction from the sewer system as these locations are both located upstream of the pressure main. In addition to that, the juncture of Heeze, Sterksel and Leende domestic wastewater inflow is chosen as the third implementation location, which is located downstream of the pressure main.
The implementation of the sewer mining technology upstream of the pressure main resulted in high dissolved sulphide concentrations and therefore led to considerable corrosion and odour problems in Riool-Zuid. On the other hand, when it was implemented downstream of the pressure main, the corrosion and odour problems were observed to be minimal. However, it is worth emphasizing that the distance between the sewer mining technology and the River Dommel plays also a crucial role in selecting the implementation location since the primary objective of this study is to feed the base flow of the River Dommel in an efficient, reliable, and cost-effective manner.
De Meren represents the nearest location to the River Dommel. Moreover, the existing infrastructure at the de Meren control station, including an adequately sized building, presents a distinct advantage. This eliminates the need for additional construction costs, and concurrently minimizes the expenses associated with the installation of piping. Despite the fact that implementing the sewer mining technology in de Meren resulted in higher dissolved sulphide concentrations and more noticeable corrosion problems in Riool-Zuid, the required nitrate dosages for corrosion control were found to be less than those required for implementing the sewer mining technology in Aalst. Regarding the water quantities, sewer mining implementation in de Meren yielded flow rates in the River Dommel ranging from 0.5446 to 0.1004 m3/s slightly below the observed rates in Aalst, which ranged from 0.5454 to 0.1021 m3/s. Furthermore, in terms of cost analysis, the total treatment cost for the FO-RO system was determined to be approximately 1.67 €/m3.
In conclusion, this study reveals that FO-RO hybrid system can be applied as a sewer mining technology at the Meren control station to boost the base flow of the River Dommel during the summertime to minimize the water quality problems in River Dommel.

Sewage systems hold a critical function within the fabric of urban infrastructure, primarily by ensuring efficient wastewater management. Within this network, sewage pumping stations emerge as important components. The performance of such stations is susceptible to being undermined by system failures and malfunctions, which can cause significant implications for both public health and occurrences of Combined Sewer Overflow (CSO) events. Consequently, discerning the patterns and root causes of these failures is of great importance.
The present study explores and seeks to understand the reliability of sewage pumping stations, particularly in the setting of the Department of Public Works in Rotterdam. The scope of this study is confined to data collected between 2016 and 2020. The research encompasses a diverse range of interconnected aspects, such as examining discrepancies in failure data, categorizing types of failures, tracking changes in failure patterns over time, and selecting a fitting statistical model to accurately represent the findings. The core focus of this study is to formulate an analysis framework to assess the reliability and failure patterns in wastewater pumping stations. In these patterns, various trends can be discerned through interarrival time - the period between two failures. For instance, an increasing trend indicates less frequent failures, suggesting improved reliability of the pumps. The devised framework combines both objective and subjective trend analyses, multiple trend tests, and employs a range of models such as the Homogeneous Poisson Process (HPP), Renewal Process (RP), and Non-Homogeneous Poisson Process (NHPP). This methodological approach is structured to facilitate a better understanding of the patterns of system behavior and shifts. Analyzing pump performance patterns over five years revealed various trends among 447 pumps studied. Of these, 254 had consistent failure patterns; 98 showed a stable trend, 146 improved over time with fewer failures, and 10 experienced more failures, indicating declining performance. The remainingpumps were divided into various trend groups or segments, demonstrating different patterns in their performance over the five years. The application of statistical methods elucidated these failure patterns, contributing to the evaluation of sewage pump station efficiency. Notwithstanding these progressions, my investigation has identified certain domains that could derive advantages from additional enhancements. The current methodology, which entailed manual configuration of kernel parameters and dependence on piecewise linear regression, was deemed insufficient for about 50% of the pumps. The study proposes the integration of sophisticated parameter estimation techniques, including Bayesian optimization or grid search, and alternative modeling methodologies to tackle this issue. It is recommended that forthcoming research expands its scope beyond Rotterdam and investigates a wider variety of pump mechanisms to validate the generalizability of the findings presented in this study. In conclusion, this thesis develops an analytical framework based on examination of failure patterns and system dynamics. It establishes a platform for future progress by outlining a distinct pathway for prospective investigations pertaining to the failures in sewage pumping stations.

Stormwater runoff carries solids from streets to the storm sewer and waterbodies, causing sediment accumulation, reduced hydraulic capacity and water pollution. Urban stormwater management is essential, but limited information on sediment behavior and treatment methods hinders decision-making. This study investigated sediment characteristics in Amsterdam, revealing variations across the system, with finer material near the outfall. Settling velocities were lower at the end of the system and resuspension was more likely near the outfall. Monitoring sediment dynamics during rainfall events showed that high-intensity events can mobilize and transport solids. Deviations from standardized test protocols emphasize the need to consider sediment behavior when interpreting predictions. Recommendations include extensive sampling campaigns, collecting both sediment and water samples, refining sampling protocols and investigating resuspension and transportation processes.

This thesis examines the implementation of risk-based sewer asset management, with a specific focus on addressing the existing shortcomings in current practices. Notably, the neglect of sewer failure risks often leads to suboptimal allocation of resources. The primary aim of this research is to develop a comprehensible methodology for risk-based sewer asset management in the Netherlands. The proposed methodology employs a combined risk matrix approach to assess the level of risk associated with sewer collapse. This assessment takes into account both the probability of failure and the potential consequences of such failures. The thesis primarily focuses on the risk of sewer collapse within the context of the Netherlands. To demonstrate the applicability of the methodology, a case study is conducted in the municipality of Nissewaard. The outcomes of this case study are then compared to the conventional approach employed in Dutch sewer asset management. Through this analysis, the study emphasizes the necessity of establishing a practical roadmap for implementing risk-based sewer asset management. Additionally, recommendations are made for enhancing the objectivity of sewer inspections and developing a sewer deterioration model. The findings reveal that the adoption of risk-based asset management is more cost-effective in mitigating the risk of sewer collapse when compared to the prevailing replacement strategy. The research aims to bridge the gap between academic theory and practical application by providing a straightforward methodology grounded in prior research. In order to advance the field of risk-based approaches, this study calls for further research into the potential obstacles associated with implementing risk-based asset management. Such investigations will contribute to a better understanding of the challenges and facilitate the successful adoption of risk-based sewer asset management practices.