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Managing stormwater volume and quality has become an important issue in urban hydrology. Impervious cover associated with urbanization increases surface runoff volumes and degrades the water quality of urban streams and rivers. Cities with combined stormwater and sewer lines such as Philadelphia, have been tasked with decreasing runoff volumes to help reduce combined sewer overflows and improve the water quality of local waterways. The Philadelphia Water Department uses the Environmental Protection Agency’s Storm Water Management Model (SWMM) to predict runoff and evaluate if proposed stormwater infrastructure will reduce overflows. This study focused on the hydrogeological properties of grassy areas on and near Temple University’s main campus in north Philadelphia. The dataset includes terrestrial LiDAR, ground penetrating radar, soil moisture sensor, surface compaction, and double ring and mini disk infiltrometer measurements. These data were used to establish what controls infiltration rates in the area and also provide input parameters for a SWMM model. A terrestrial LiDAR scan of the Berks St. site, a grassy vacant lot located just east of Temple’s campus was used to generate a high-resolution digital elevation model. This elevation model was used to calculate the depression storage parameter, partition subcatchments in the SWMM model, and calculate a topographic wetness index (TWI). The TWI is a microtopography-based predictor of where runoff will collect and infiltrate. The TWI assumes a homogeneous infiltration rate and that runoff is routed by topography. This TWI was compared with soil moisture sensor measurements to determine if the microtopographic index could predict the majority of change in soil moisture at the field site. To determine if accounting for buried debris helped strengthen the TWI, GPR was used to map the extent and depth of subsurface objects. The results indicate that the TWI and GPR data could not predict where runoff would accumulate and then infiltrate because the TWI’s assumptions were not met. Measurements made with a double ring infiltrometer indicate that infiltration rates at the site were both high and heterogeneous (40 to 1060 mm/hr), allowing precipitation to infiltrate into the subsurface rather than become runoff, minimizing the influence of microtopography. Co-located surface compaction and double ring infiltrometer measurements at sites on and nearby Temple’s campus showed a negative correlation between surface compaction and infiltration rate (R2 = 0.67). Compacted areas on campus had lower infiltration rates and exhibited depression storage and runoff during rain events. Less compacted areas off campus had higher infiltration rates and exhibited no depression storage or runoff. The results of this study showed variance in surface compaction caused grassy areas around Temple’s campus respond differently to rain events. The results not only provided field-based parameter values for a SWMM model, but shows that compaction’s influence on infiltration should be considered when constructing a SWMM model. Runoff volumes in SWMM may be underestimated if compacted grassy areas are modeled with high infiltration rates. / Geology

Urbanization alters land cover by increases in impervious areas, resulting in large increases in runoff, sediment, and nutrient loadings downstream. These changes cause flooding, eutrophication, and harmful algal blooms. Stormwater control measures (SCMs) are used to address these concerns and are designed based on inflow loads. Thus, estimating nutrient and sediment loads from developed watersheds is vitally important for meeting the impacts of urbanization. Today, stormwater events are characterized mainly by watershed models using little, if any, actual field monitoring data. The simple event mean concentration (EMC) wash-off approach by land use is a common practice used by practitioners for estimating loads. Pollutants accumulate on surfaces during dry periods, making EMC a function of antecedent dry period (ADP). An EMC results from wash-off of accumulated pollutants from catchment surfaces during runoff events. However, it assumes concentration is constant across events from a particular land use and several studies found little to no correlation between constituent concentrations in stormwater and ADP. Build-up/wash-off equations were developed to account for variation of concentrations between events; however, the required parameters are difficult to estimate. This study applied machine learning approaches with a national dataset along with monitoring and modeling studies at watershed scales to improve predictions of stormwater quantity and quality. First, we obtained stormwater quality data from the National Stormwater Quality Database (NSQD), which is the largest data repository of stormwater quality data in the U.S., and used Bayesian Network Structure Learner (BNSL), a machine learning approach, to discover which climatological or catchment characteristics most significantly affect stormwater quality. Second, we developed and applied Random Forest (RF), a data-driven method, to predict nutrients and sediment EMCs in urban runoff. Third, we applied the Storm Water Management Model (SWMM), a widely used urban watershed model, to an urban watershed and assessed the best fit estimates of SWMM parameters and hydrological response of the watershed during dry and wet hydroclimatic conditions. Last, we conducted a monitoring and modeling study at a catchment scale and assessed the role of land use on stormwater quantity and quality to optimize and investigate the build-up/wash-off parameters for multiple urban land uses for nutrients and sediment. The results presented in this dissertation can help stakeholders, urban planners, and SCM designers improve estimates of nutrients and sediment loads and thus achieve more effective treatment of stormwater, better attain water quality goals, and protect downstream water bodies. / Doctor of Philosophy / Urban development results in increased hardscapes (impervious surfaces), which increases runoff and subsequent pollution from nutrients and sediment carried off land surfaces. This negatively impairs the health of receiving streams, lakes, rivers, and estuaries. A variety of management practices are available for reducing these impacts. Practice size is based on the water quantity and quality it will receive. Thus, estimating the quantity of nutrients and sediment from developed areas is crucial to meet water quality goals. However, designs of stormwater management practices typically use historical data based on land use; rather than conducting new monitoring studies to determine actual pollution loads. Event mean concentration (EMC) is a common method used to estimate wash-off of pollutants from the land. Pollutants accumulate on surfaces during dry periods, making EMC a function of antecedent dry period (ADP) which is the time between storm events. An EMC results from wash-off of accumulated pollutants from urban areas during a storm event. However, EMC assumes pollutant concentration is constant across any storm event from a particular land use. Several studies found little to no correlation between nutrients and sediment concentrations in stormwater and ADP. Build-up/wash-off equations were developed to account for variability of concentrations between storm events; however, there are several parameters that are difficult to estimate. This study applied machine learning approaches to a national stormwater quality dataset and conducted monitoring and modeling studies at progressively smaller scales to improve the predictions of stormwater quantity and quality. First, we obtained stormwater quality data from the National Stormwater Quality Database (NSQD), which is the largest data repository of its type in the U.S., and used Bayesian Network Structure Learner (BNSL), a machine learning method, to discover which climatological or catchment characteristics most significantly affect stormwater quality. Second, we developed and applied Random Forest (RF), also a machine learning method, to predict nutrients and sediment EMCs in stormwater. Third, we applied the Storm Water Management Model (SWMM), which is the most widely used rainfall/runoff model, to an urban area and assessed the best fit estimates of SWMM parameters during dry and wet years. Last, we conducted a monitoring and modeling study at smaller scales and assessed the role of land use on stormwater quantity and quality and estimated build-up/wash-off parameters for multiple urban land uses for nutrients and sediment using optimization. The results presented in this dissertation can help stakeholders, urban planners, and stormwater practice designers improve estimates of the quantity of nutrients and sediment in stormwater, achieve more effective treatment of stormwater, attain water quality improvement goals, and protect the health of receiving streams and downstream water bodies.

[pt] A pesquisa analisou o material concreto permeável visando a sua aplicação como revestimento de pavimentos permeáveis para atenuação de cheias urbanas. Desta maneira, diversas misturas foram estudadas experimentalmente, objetivando determinar suas características hidráulicas e mecânicas. Com base nos resultados experimentais e no uso pretendido em calçadas, foi definida a mistura mais adequada. A fim de analisar o impacto desta solução no escoamento superficial, foi escolhida a bacia hidrográfica do Rio dos Macacos localizada no Bairro Jardim Botânico no Rio de Janeiro a qual apresenta problemas recorrentes de inundação. Em função das características da bacia e em critérios mecânicos e hidráulicos do pavimento permeável de concreto, foram escolhidas as áreas para a sua aplicação e opavimento foi dimensionado. A bacia estudada foi modelada com auxílio dosoftware Storm Water Management Model para os cenários antes e após a aplicação dos pavimentos permeáveis de concreto em calçadas. Por fim, foi estimado o custo direto da solução proposta. Os resultados do estudo experimental do concreto permeável demonstraram que o material possui permeabilidade e resistências mecânicas adequadas para aplicação em calçadas. Os resultados do modelo computacional, obtidos através da comparação de hidrogramas de cheia, evidenciaram satisfatório amortecimento. A análise de custo demonstrou que a solução é economicamente viável. / [en] New techniques of urban drainage have emerged in order to mitigate the negative effects of urbanization. Initially, in the United States in 1970 denominated Best Management Practices (BMPs) and then in United Kingdom in 1980 as Sustainable Urban Drainage Systems (SUDS). The goal of these techniques is to reproduce the natural hydrological cycle, mitigating flood peaks and reducing diffuse pollution through infiltration, retention and transport devices such as green roofs, percolation trenches and pervious pavements. (Canholi, 2014). Unlike traditional pavements, pervious pavements allow the infiltration of rainwater on the surface. The infiltrated water is stored temporarily before use, infiltration into the soil, or downstream controlled discharge. According to Field et al (1982) and Mullaney and Lucke (2013), all types of pervious pavement share the same objectives, which are: to allow the infiltration of water on its surface; reduce the increase in the rate and volume of runoff; and improve degradation of water quality resulting from urbanization and land use change. Depending on the soil permeability, they still have the advantage of allowing the recharge of the aquifers.

Master of Science / Biological & Agricultural Engineering / Stacy L. Hutchinson / Increasing attentiveness to climate change and the dependence of human life on natural resources has spurred awareness about the detrimental impacts of human activity on the environment. Ecosystem services, or the benefits that humans derive from ecosystems, have changed more in the past 50 years than in any other comparable period in human history (Carpenter et al., 2009).The dilemma of managing the trade-off between immediate human needs and maintaining the ability of the Earth to provide ecosystem services is considered to be one of the largest challenges of this century (Foley et al., 2005). The ecosystem service concept aims maximize the provision of services across an entire ecosystem to achieve overall ecosystem health through land management, policy, and economic decisions. The intent of this research was to improve such decisions by increasing the understanding about the relationship between urban best management practices and freshwater provision, erosion regulation, and flood regulation ecosystem services. Fifty-six land management scenarios with varying densities of BMP application were simulated using the Stormwater Management Model (SWMM). The ecosystem services resulting from these land management scenarios were quantified using indices developed by Logsdon and Chaubey (2013). Results demonstrate that the application of bioretention cells improve both freshwater provision and erosion regulation services immediately downstream from the implementation site, and an increase in erosion regulation services was observed at the greater watershed scale. There was no change in the provision of freshwater, erosion regulation, or flood regulation services observed by the application of green roofs or rain barrels at either scale of analysis.

No description available.

Urbanization increases runoff during storm events due to a reduction in vegetation and an increase in impervious surfaces, which limits the land's capacity to absorb and slow down water. This increase in runoff contributes to channel erosion. While extensive research exists on the hydrologic benefits of various types of stormwater control measures (SCMs), the relationship between urbanization, widespread SCM implementation, and channel stability in headwater streams remains less explored. Additionally, the impact of climate change (CC) on SCMs, with its growing focus due to improved global and regional CC models and data, is a critical area of study. However, most existing studies rely on simplified design storm analyses and unit-area runoff models, and there is a lack of comprehensive research evaluating the long-term, continuous hydrologic response of SCMs under future CC scenarios. This study presents an in-depth evaluation of the effectiveness of SCMs in maintaining channel stability in urbanized headwater streams, with a particular focus on the challenges posed by urbanization and CC. Conducted in a small catchment in Montgomery County, Maryland, USA, the study employs a sequential hierarchical modeling approach integrating the Storm Water Management Model (SWMM) with the Hydrologic Engineering Center's River Analysis System (HEC-RAS). First, the impact of a stormwater management system design following Maryland's Unified Stormwater Sizing Criteria (USSC) on channel stability was investigated. Simulation over 16 years (2004-2020) demonstrated that the majority of storm events were short in duration, with the greatest peak flows resulting from storm events with durations less than 24 hours. However, results indicated that despite the use of multiple SCMs, channel changes, including both degradation and aggradation up to 1.2 m, are likely over a period of 16 years. Study results indicate SCMs should be designed using continuous simulation models to simulate pre- and post-development sediment transport. Secondly, the impact of SCMs and CC on flow regime and channel stability was examined, challenging the previous simplified analyses. The findings highlight that future CC scenarios, characterized by decreased total rainfall but increased intensity, will likely shift watershed hydrology towards a flashier regime, exacerbating channel erosion. To address these shortcomings, a multicriteria design approach for SCMs is required, considering local sediment transport capacity and the complexities of urban catchments under changing climatic conditions. Lastly, evaluation of the impact of proposed stormwater regulations on channel stability using a novel three-step methodology revealed that SCM design goals focused on maintaining pre-development sediment transport or excess shear stress could reduce channel disturbance. Overall, this study illustrates the need for more nuanced and holistic approaches to stormwater management to ensure channel stability, especially in the face of the challenges posed by climatic changes. / Doctor of Philosophy / As cities grow, with more buildings and roads replacing green spaces, managing stormwater becomes a crucial challenge. Without enough soil and plants to absorb it, stormwater rushes over these hard surfaces, contributing to stream erosion. This urban scenario sets the stage for my research, which investigated effective ways to handle stormwater in cities to protect small, local streams. The focus of this study was to understand the performance of stormwater control measures (SCMs), which are engineered structures designed to manage this excessive runoff in urban environments. The key question is: Are SCMs effective, especially as we face the impacts of climate change? This research was conducted in a small watershed in Montgomery County, Maryland, using computer simulations to replicate water flow and stream conditions over a 16-year period. The findings reveal that, despite using SCMs, streams can still experience significant changes. This is especially true during intense, short-duration storms that can rapidly increase stream flow and cause channel erosion. With climate change, these problems may increase. Future weather patterns could lead to less frequent but more intense rainstorms. This study suggests that our approach to designing SCMs needs to be more sophisticated, taking into account not only the amount of water running into streams, but also the amount of coarse sediment moving during floods. In summary, this research highlights the need for comprehensive strategies in urban water management to ensure the stability and health of urban streams amidst the challenges of increasing urban development and climatic changes.

Made available in DSpace on 2014-07-29T15:01:53Z (GMT). No. of bitstreams: 1 Dissertacao Karla Alcione da Silva.pdf: 1636555 bytes, checksum: d36dd50302f1e6a5b506033da1f1abb0 (MD5) Previous issue date: 2007-08-31 / This research presents an evaluation of the eficiency of four flood control measures applied to an urban basin in the city of Goiânia, State of Goiás, Brazil. Goiânia shows frequent flooding problems. The following factors have been identified as causes of the floodings: (1) significant number of impervious areas (2) lack of green areas, (3) insuficient capacity of the pipe network to convey the produced water volume. Small detention basins, infiltration trenches and the increase of permeable areas (30-50%) within parcels have been evaluated as flood control measures as well as the use of the Lago do Bosque dos Buritis as a detention basin. For this purpose, the Stormwater Management Model SWMM has been applied for evaluating 11 hypothetic management measures in the water basin. The later control measures were evaluated individually as combined. In determining the impervious area index of the studied area, field visits have been carried out, which showed high imperviousness. (86.16%). A synthetic rainfall time series, derived from the equation proposed by Costa e Brito (1999) with recurrence of 2 years, has been used in the simulations. Horton`s equation was applied to represent infiltration with parameters presented in Moura (2005). The scenario which combines the use of infiltration trenches and the increase of pervious areas to 50% has shown to be the best solution in reducing peak flow with 43% eficiency. On the other hand, the scenario using detention basins presented the smallest efficiency (3%). / O presente trabalho apresenta a avaliação da eficiência de quatro métodos de controle de enchentes em uma bacia urbana localizada na cidade de Goiânia, que apresenta graves problemas de inundação. Estes alagamentos devem-se a alguns fatores que foram levantados, tais como: muitas áreas impermeabilizadas, poucas áreas verdes e rede com dimensões pequenas e insuficientes para o escoamento de todo o volume produzido. Foram analisadas a implantação de microservatórios de detenção, trincheira de infiltração, o aumento da área permeável no interior do lotes (de 30% e 50%) e o uso dos lagos do Bosque dos Buritis como dispositivo de controle. Para tanto, procederam-se simulações no modelo computacional SWMM Storm Water Management Model em que foram avaliados 11 cenários hipotéticos na bacia, que consistiram na aplicação dos dispositivos de forma individual e em conjunto. Para a determinação do índice de impermeabilização da área estudada foi necessário realizar um levantamento em uma área amostra, o qual demonstrou uma média de 86.16% de impermeabilização em cada lote. A precipitação utilizada foi uma série sintética, determinada por meio da equação de chuva desenvolvida por Costa e Brito (1999) com tempo de recorrência adotado de 2 anos. Para representar a infiltração, optou-se por trabalhar com a equação de infiltração de Horton, segundo os parâmetros de Moura (2005). O cenário simulado com a implantação de trincheira de infiltração e o aumento da área permeável em 50% apresentou aproximadamente 43% de eficiência na redução da vazão de pico, indicando que essa poderia ser a melhor solução para o problema analisado, enquanto que o cenário com microreservatórios apresentou a menor eficiência, aproximadamente 3%.