Browsing by Author "Mugume, Seith N."

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    Comparison of SWAT and HEC-HMS model performance in simulating catchment runof
    (Journal of Applied Water Engineering and Research, 2023) Sempewo, Jotham Ivan; Twite, Daniel; Nyenje, Philip; Mugume, Seith N.
    Globally, surface water sources are important sources of drinking water and knowledge on their availability and sustainability is important for their protection. Such studies in data-poor regions are very limited. This paper compares the performance of SWAT and HEC-HMS in the event and continuous modeling of rainfall–runoff in two tropical catchments, a low laying and a mountainous one. Model calibration and validation were done using observed streamflow data at Busiu station for Manafwa and at Sezibwa falls for Sezibwa for the period 2000–2013. The results were compared based on objective functions and also the t-test was used to test the statistical significance of the difference in performance. The results show that HEC-HMS performed better than SWAT in Manafwa catchment (p = .003 and p = .000 during calibration and validation, respectively) while in Sezibwa the difference in model performance was not statistically significant (p = .63) although, during calibration, HEC-HMS performed better (p = .01).
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    Effectiveness of infiltration galleries in reduction of surface runoff and flooding in urban areas
    (2019) Kirenda, Viola; Mugume, Seith N.
    Many times the design of drainage structures for storm water management (SWM) follows the conventional approach of conveying flows downstream as quickly as possible. Consequently, low lying and mostly urban poor areas suffer flooding problems. As a solution, the land upstream can be utilized to its maximum potential by incorporating infiltration practices that allow water to infiltrate before it is released downstream. This paper is based on a case study research project carried out at a plot scale on Makerere hill, Kampala, Uganda focused on investigation of the effectiveness of appropriately designed infiltration galleries on reduction of surface runoff. Results indicated that use of infiltration galleries can result into a 40% percentage reduction in the generated runoff. The results further suggested that this reduction is dependent on the soil permeability, size of available land and the size and number of perforated embedded pipes used for the infiltration structure.
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    Enhancing resilience in urban water systems for future cities
    (Water Supply, 2015) Mugume, Seith N.; Diao, Kegong; Astaraie-Imani, Maryam; Fu, Guangtao; Farmani, Raziyeh; Butler, David
    In future cities, urban water systems (UWSs) should be designed not only for safe provision of services but should also be resilient to emerging or unexpected threats that lead to catastrophic system failure impacts and consequences. Resilience can potentially be built into UWSs by implementing a range of strategies, for example by embedding redundancy and flexibility in system design, or by rehabilitation to increase their ability to maintain acceptable customer service levels during unexpected system failures. In this work, a new resilience analysis is carried out to investigate the performance of a water distribution system (WDS) and an urban drainage system (UDS) during pipe failure scenarios. Using simplified synthetic networks, the effect of implementing adaptation (resilient design) strategies on minimising the loss of system functionality and cost of UWSs is investigated. Study results for the WDS case study showthat the design strategy in which flexibility is enhanced ensures that all customers are served during single pipe failure scenarios. The results of the UDS case study indicate that the design strategy incorporating upstream distributed storage tanks minimises flood volume and mean duration of nodal flooding by 50.1% and 46.7%, respectively, even when system functionality is significantly degraded. When costs associated with failure are considered, resilient design strategies could prove to be more cost-effective over the design life of UWSs.
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    Evaluation of functional resilience in urban drainage and flood management systems using a global analysis approach
    (Urban Water Journal, 2017) Mugume, Seith N.; Butler, David
    Enhancing resilience in urban drainage systems (UDSs) requires new evaluation approaches that explicitly consider vital interactions between threats, system performance and resulting failure impacts during both normal and unexpected (exceptional) loading conditions. However, current reliability-based approaches only focus on prevention of functional (hydraulic) failures resulting from a specified design storm. In this study, the global resilience analysis (GRA) approach is further extended for evaluation of UDS performance when subject to a wide range of random functional failure scenarios (extreme rainfall) with varying magnitude, duration, and spatial distribution. The resulting loss of system functionality during the simulated failure scenarios is quantified using total flood volume and mean flood duration. System residual functionality for each considered rainfall block loading scenario is quantified using the functional resilience index. The developed approach has been successfully applied to test and characterise the functional resilience to extreme rainfall of an existing UDS in Kampala city, Uganda. The study concluded that: (1) UDS functional resilience is significantly influenced by both occurrence of short duration, high intensity rainfall events and spatial rainfall variation during extreme rainfall conditions and (2) future planning and design of resilience enhancement strategies should apply spatially distributed rainfall inputs to facilitate effective sizing of potential adaptation strategies.
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    A global analysis approach for investigating structural resilience in urban drainage systems
    (Water research, 2015) Mugume, Seith N.; Gomez, Diego E.; Fu, Guangtao; Farmani, Raziyeh; Butler, David
    Building resilience in urban drainage systems requires consideration of a wide range of threats that contribute to urban flooding. Existing hydraulic reliability based approaches have focused on quantifying functional failure caused by extreme rainfall or increase in dry weather flows that lead to hydraulic overloading of the system. Such approaches however, do not fully explore the full system failure scenario space due to exclusion of crucial threats such as equipment malfunction, pipe collapse and blockage that can also lead to urban flooding. In this research, a new analytical approach based on global resilience analysis is investigated and applied to systematically evaluate the performance of an urban drainage system when subjected to a wide range of structural failure scenarios resulting from random cumulative link failure. Link failure envelopes, which represent the resulting loss of system functionality (impacts) are determined by computing the upper and lower limits of the simulation results for total flood volume (failure magnitude) and average flood duration (failure duration) at each link failure level. A new resilience index that combines the failure magnitude and duration into a single metric is applied to quantify system residual functionality at each considered link failure level. With this approach, resilience has been tested and characterized for an existing urban drainage system in Kampala city, Uganda. In addition, the effectiveness of potential adaptation strategies in enhancing its resilience to cumulative link failure has been tested.
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    Moving from reliability to resilience-based evaluation of urban drainage infrastructure: A case study of Kampala, Uganda
    (Quebec, Canada, 2015) Mugume, Seith N.; Butler, David
    The performance of existing urban drainage systems (UDSs) in various cities is increasingly threatened by multiple and uncertain threats such as climate change, rapid urbanisation and infrastructure failure which lead to negative flooding impacts and consequences. However, conventional urban drainage design and rehabilitation approaches tend to focus on minimising the probability of hydraulic failures resulting from a chosen design storm as a basis for determining the flood protection service level delivered by a given system (Butler and Davies, 2011; Sun et al., 2011; Thorndahl and Willems, 2008). Such hydraulic-reliability based approaches may be insufficient for ensuring accepteable flood protection levels in cities during unprecedented extreme events. Consequently, to enhance the resilience of UDSs, new and computationally efficient evaluation approaches that can enable explicit consideration of vital interactions between threats, system performance and resulting failure impacts during both normal and exceptional loading conditions are required (Butler et al., 2014; Kellagher et al., 2009; Mugume et al., 2015).
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    Multifunctional urban flood resilience enhancement strategies
    (Thomas Telford Ltd, 2017) Mugume, Seith N.; Melville-Shreeve, Peter; Gomez, Diego; Butler, David
    Enhancing resilience in urban drainage systems (UDSs) can be achieved by implementing a range of strategies that minimise the magnitude and duration of flooding during or after the occurrence of unexpected system failures. Dual-purpose rainwater harvesting (RWH) systems provide a promising multifunctional resilience-enhancing strategy due to their associated multiple benefits such as water conservation and distributed control of storm water. However, their effectiveness in respect to minimisation of resulting flooding impacts and provision of alternative water supplies during unexpected system failures has not been explicitly investigated at a city district or catchment scale. This paper applies the global resilience analysis approach to investigate the effect of implementing a set of multifunctional RWH strategies on improvement of UDS resilience to random cumulative link (sewer) failure, using a case study of the Nakivubo system in Kampala, Uganda. The resulting water supply resilience enhancement benefits are also investigated. The study results reveal that catchment-scale implementation of suitably designed RWH systems provides an effective strategy that improves the system’s global resilience to flooding by up to 25%, while simultaneously providing up to 30% of the household water supply requirements in the case study area.
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    Resilience-based evaluation of urban drainage systems: The 'Safe & SuRe' Approach Paper 16 -Session 5: Emerging technology and asset management
    (Research gate, 2016) Mugume, Seith N.; Butler, David
    The need to develop more resilient urban drainage systems (UDSs) is now widely recognised as key to maintaining acceptable flood protection service levels in cities in view of emerging climate-related, urbanisation and ageing infrastructure threats. In order to effectively operationalise resilience in urban flood management, new quantitative evaluation approaches that consider ‘all possible threats’ including existing network capacity and asset failures such as sewer collapse, blockage or equipment malfunction are required. This paper presents the Safe & SuRe approach that seeks to ensure that UDSs are designed or retrofitted not only for safe (reliable) provision of services during normal conditions but also to be more resilient to extreme loading conditions. Specifically, the paper describes the developed Safe & SuRe framework and presents a summary of results obtained by applying the middle state-based Global Resilience Analysis (GRA) method to systematically evaluate: (i) the effect of a wide range of functional (hydraulic) and structural (sewer) failures and on the ability of an existing UDS in Kampala, Uganda to minimise the resulting magnitude and duration of flooding and (ii) investigate the effectiveness of a set of promising adaptation strategies on improvement of its resilience to flooding. Study results indicate that occurrence sewer failures leads to significant loss of functionality of the existing UDS (and hence its level of resilience to flooding) that is comparable to the effect of extreme rainfall. The results further indicate that when compared to centralised storage and improved asset management, the distributed storage strategy is more effective and leads to a reduction in total flood volume and mean flood duration of up to 34% and 24% respectively even when the UDS structure is significantly degraded. The presented GRA method provides a computationally efficient approach that is suitable for evaluating resilience in large urban drainage networks without prior knowledge of threat (extreme rainfall or sewer failure) occurrence probabilities.