Seneshaw Tsegaye
@fgcu.edu
Assistant Professor, Department of Environmental and Civil Engineering
Florida Gulf Coast University
EDUCATION
Ph.D., University of South Florida, Civil and Environmental Engineering, 2013
Scopus Publications
Scopus Publications
Thomas M. Missimer, James H. MacDonald, Seneshaw Tsegaye, Serge Thomas, Christopher M. Teaf, Douglas Covert, and Zoie R. Kassis
MDPI AG
Mercury (Hg) is a toxic metal that is easily released into the atmosphere as a gas or a particulate. Since Hg has serious health impacts based on human exposure, it is a major concern where it accumulates. Southern Florida is a region of high Hg deposition in the United States. It has entered the southern Florida environment for over 56 MY. For the past 3000 to 8000 years, Hg has accumulated in the Everglades peatlands, where approximately 42.3 metric tons of Hg was deposited. The pre-industrial source of mercury that was deposited into the Everglades was from the atmosphere, consisting of combined Saharan dust and marine evasion. Drainage and the development of the Everglades for agriculture, and other mixed land uses have caused a 65.7% reduction in the quantity of peat, therefore releasing approximately 28 metric tons of Hg into the southern Florida environment over a period of approximately 133 years. Both natural and man-made fires have facilitated the Hg release. The current range in mercury release into the southern Florida environment lies between 994.9 and 1249 kg/yr. The largest source of Hg currently entering the Florida environment is from combined atmospheric sources, including Saharan dust, aerosols, sea spray, and ocean flux/evasion at 257.1–514.2 kg/yr. The remobilization of Hg from the Everglades peatlands and fires is approximately 215 kg/yr. Other large contributors include waste to energy incinerators (204.1 kg/yr), medical waste and crematory incinerators (159.7+ kg/yr), and cement plant stack discharge (150.6 kg/yr). Minor emissions include fuel emissions from motorized vehicles, gas emissions from landfills, asphalt plants, and possible others. No data are available on controlled fires in the Everglades in sugar farming, which is lumped with the overall peatland loss of Hg to the environment. Hg has impacted wildlife in southern Florida with recorded excess concentrations in fish, birds, and apex predators. This bioaccumulation of Hg in animals led to the adoption of regulations (total maximum loads) to reduce the impacts on wildlife and warnings were given to consumers to avoid the consumption of fish that are considered to be contaminated. The deposition of atmospheric Hg in southern Florida has not been studied sufficiently to ascertain where it has had the greatest impacts. Hg has been found to accumulate on willow tree leaves in a natural environment in one recent study. No significant studies of the potential impacts on human health have been conducted in southern Florida, which should be started based on the high rates of Hg fallout in rainfall and known recycling for organic sediments containing high concentrations of Hg.
Long D. Nguyen, Alexis Slobodzian, Claude Villiers, and Seneshaw Tsegaye
Springer Nature Singapore
Daniel W. Schroeder, Seneshaw Tsegaye, Thomas L. Singleton, and Kevin K. Albrecht
MDPI AG
Stormwater control is an urgent concern in cities where the increased impervious surface has disrupted natural hydrology, particularly causing a reduction in groundwater recharge which is the source of potable water supply for many communities. Water managers are increasingly turning towards infiltration-based stormwater management options (ISMOs) to help minimize flooding and mitigate the impact of urbanization on the local hydrologic systems. This paper offers a unique hydrologic and hydraulic (H&H) modeling approach using the Geographic Information System (GIS) and Interconnected Pond and Channel Routing (ICPR) software to help quantify the associated flood stage and groundwater recharge benefits of using ISMOs. The proposed approach incorporated ICPR percolation links and utilization of the curve number and Green-Ampt infiltration methods into the case study design, as well as an analysis of the effectiveness of including low-impact development practices. This analysis shows a 13–36% reduction in stormwater volume leaving the proposed site when percolation links were utilized to account for percolation from the proposed ISMOs. These reduction provides an indirect estimate of groundwater recharge benefits. The conversion from impervious parking to a pervious one and inclusion of rainwater harvesting from the roof area resulted in a further reduction in peak stages ranging from 1.20 to 7.62 cm.
Long D. Nguyen and Seneshaw Tsegaye
American Society of Civil Engineers
Kevin D. Orner, Seneshaw Tsegaye, Hélène Kassouf, Komal Rathore, Aydin Sunol, and Jeffrey A. Cunningham
Informa UK Limited
Seneshaw Tsegaye, Kristopher C. Gallagher, and Thomas M. Missimer
Elsevier BV
Abstract Urban sprawl, climate change, and resource scarcity will impact how sustainable cities approach future challenges surrounding the management of water resources. A major component of all urban water systems is distribution, which constitutes approximately 80-85% of the total cost of a water-supply system. Traditionally, water distribution systems (WDS) are designed using the ‘worst scenario,’ or ‘robustness’ to improve system reliability. Deterministic assumptions are historically inaccurate and require a new design approach that recognizes uncertainties and offers more adaptability. A Genetic Algorithm based Flexibility Optimization (GAFO) model is developed in Visual C++ and linked with EPANET for the design of WDS that are more adaptable. Unlike traditional GA optimization, GAFO involves a dynamic decision-making process that recognizes a range of possible future conditions and maximizes the flexibility of a WDS at the lowest cost. The outcome is a WDS that can follow different future trajectories (changing conditions) and generate a staged implementation strategy that allows a stepwise evolution of the WDS over time. The GAFO model was tested on several hypothetical cases and was found to perform well in terms of convergence and flexibility. Compared with conventional, non-flexible designs, cost savings in the range of 35% to 72% were realized.
Abdullah H.A. Dehwah, Donald M. Anderson, Sheng Li, Francis L. Mallon, Zenon Batang, Abdullah H. Alshahri, Seneshaw Tsegaye, Michael Hegy, and Thomas M. Missimer
Desalination Publications
Seneshaw Tsegaye, Thomas M. Missimer, Jong-Yeop Kim, and Jason Hock
MDPI AG
Current models in design of urban water management systems and their corresponding infrastructure using centralized designs have commonly failed from the perspective of cost effectiveness and inability to adapt to the future changes. These challenges are driving cities towards using decentralized systems. While there is great consensus on the benefits of decentralization; currently no methods exist which guide decision-makers to define the optimal boundaries of decentralized water systems. A new clustering methodology and tool to decentralize water supply systems (WSS) into small and adaptable units is presented. The tool includes two major components: (i) minimization of the distance from source to consumer by assigning demand to the closest water source, and (ii) maximization of the intra-cluster homogeneity by defining the cluster boundaries such that the variation in population density, land use, socio-economic level, and topography within the cluster is minimized. The methodology and tool were applied to Arua Town in Uganda. Four random cluster scenarios and a centralized system were created and compared with the optimal clustered WSS. It was observed that the operational cost of the four cluster scenarios is up to 13.9 % higher than the optimal, and the centralized system is 26.6% higher than the optimal clustered WSS, consequently verifying the efficacy of the proposed method to determine an optimal cluster boundary for WSS. In addition, optimal homogeneous clusters improve efficiency by encouraging reuse of wastewater and stormwater within a cluster and by minimizing leakage through reduced pressure variations.
Seneshaw Tsegaye, Thomas L. Singleton, Andrew K. Koeser, David S. Lamb, Shawn M. Landry, Shen Lu, Joshua B. Barber, Deborah R. Hilbert, Keir O. Hamilton, Robert J. Northrop,et al.
Elsevier BV
Abstract Urban stormwater managers have traditionally used pipes, ditches, ponds and other gray infrastructure elements to quickly divert runoff away from its main sources—buildings and roadways. In contrast, proponents of green infrastructure attempt to manage stormwater near its origin, utilizing natural drainage pathways and best management practices (BMPs) to reduce runoff and increase infiltration. In doing so, stormwater is retained where it is needed to support urban vegetation. This vegetation, in turn, helps reduce future runoff, while producing a whole range of environmental, economic, and social/human health-related benefits. Despite the many advantages of green infrastructure, retrofitting the infrastructure of a city is a costly process that requires careful planning. The transition from gray to green infrastructure requires communication between managers from different disciplines and a willingness to stray from management strategies that have defined stormwater management for centuries. The Gray to Green (G2G) green infrastructure planning tool is designed to facilitate these conversations—showing both technical and non-technical users how green infrastructure BMPs can work within the urban forest to manage stormwater on existing or proposed development sites. This paper details the data sources and research at the core of G2G—documenting all methods, equations, and assumptions used in its creation to provide users with a fully-transparent and peer-reviewed planning tool. The paper concludes with descriptions and user insights from two case studies from Tampa, Florida (United States) and Milwaukee, Wisconsin, (United States).
J. Velázquez, P. Anza, J. Gutiérrez, B. Sánchez, A. Hernando, and A. García-Abril
Elsevier BV
Abstract Due to the numerous environmental problems facing today's society, and especially urban areas, green roofs are presented as an adequate technique to fight the consequences of pollution, traffic and lack of green areas. These green structures help to reduce the effects of Urban Heat Island, to decrease noise and atmospheric pollution, to protect homes from isolation and cold; they also capture rainwater and improve biodiversity. A new methodology is presented to select the best location of green roofs in large cities. In the first phase, this methodology helps to determine the most suitable neighborhoods, analyzing four main variables of interest in urban environs: pollution, traffic, green areas and population. In order to benefit a greater number of inhabitants, the neighborhoods with the worst air quality, more traffic, less green areas and higher population density, are selected. In the second phase, we used LIDAR technology to identify available roofs for the installation of the green roofs according to the height and roof typology of the buildings. To select the optimal roofs, connectivity analysis techniques were used. The results show that the most conflictive neighborhoods from the environmental point of view are those located in the city center, so they result the ideal places for the location of green roofs. In general, all neighborhoods except one presented high connectivity values. This methodology helps to improve the connectivity of the green spaces of Madrid, favoring the dispersion of plant and animal species, air quality and promoting sustainable and quality urban development.
Kristopher C. Gallagher, Kamal Alsharif, Seneshaw Tsegaye, and Philip Van Beynen
Informa UK Limited
ABSTRACT This research analyzed the efficiency of the BMP Siting Tool developed by the US Environmental Protection Agency and the Grey-to-Green Decision Support Tool. Both tools were used in conjunction with ArcGIS 10.1 to obtain cartographic data illustrating suitable sites for bioswales and infiltration basins in Hillsborough County, Florida. The data were integrated with the Karst Aquifer Vulnerability Index (KAVI) groundwater vulnerability model. The BMP Siting Tool sited 2.80% of all bioswales and 27.89% of all infiltration basins above vulnerable areas identified by the KAVI. Alternatively, 21.66% of all bioswales and 9.62% of all infiltration basins sited by the Grey-to-Green Decision Support Tool were above vulnerable areas. The results of this analysis prompted the proposal of a supplemental framework unique to each tool’s weakness. The idea behind the supplemental framework is to determine the most suitable sites for stormwater BMPs by refining the current siting framework to better respect groundwater integrity.
M. Figueroa and D. Kincaid
Routledge
Kala Vairavamoorthy, Jochen Eckart, Seneshaw Tsegaye, Kebreab Ghebremichael, and Krishna Khatri
Springer International Publishing
With increasing global change pressures (such as urbanization and climate change) and existing unsustainable factors and risks inherent to conventional urban water management, cities in the future will experience difficulties in efficiently managing scarcer and less reliable water resources. In order to meet these challenges, there needs to be a paradigm shift to integrated urban water management (IUWM). This paradigm shift is based on several key concepts including resilience of urban water systems to global change pressures, interventions over the entire urban water cycle, reconsideration of the way water is used (and reused), and greater application of natural systems for treatment. This chapter will present an integrated framework supporting IUWM and its key principles.
K. Vairavamoorthy, J. Eckart, K. Ghebremichael and S. Tsegaye
ion and recharge. In 2007, it launched a 15-year, multisectoral plan to promote watersaving measures for consumers (metering all users and improving bill collection), curtail network losses (by bringing illegal connections into compliance), and increase wastewater treatment and reuse (by constructing tertiary treatment plants to produce recharge water). With these measures, the Green Plan seeks to reduce groundwater abstraction by 10% and the overdraft by 25%. Sources: Jiménez and Chavez, 2004; Jiménez, 2008; Jiménez and Chavez, 2010; CONAGUA, 2011. Box 9. Mexico City: Replenishing downstream aquifers
A. Pathirana, S. Tsegaye, B. Gersonius, and K. Vairavamoorthy
Copernicus GmbH
Abstract. An urban inundation model was developed and coupled with 1-D drainage network model (EPA-SWMM5). The objective was to achieve a 1-D/2-D coupled model that is simple and fast enough to be consistently used in planning stages of urban drainage projects. The 2-D inundation model is based on a non-standard simplification of the shallow water equation, lays between diffusion-wave and full dynamic models. Simplifications were made in the process representation and numerical solving mechanisms and a depth scaled Manning coefficient was introduced to achieve stability in the cell wetting-drying process. The 2-D model is coupled with SWMM for simulation of both network flow and surcharge induced inundation. The coupling is archived by mass transfer from the network system to the 2-D system. A damage calculation block is integrated within the model code for assessing flood damage costs in optimal planning of urban drainage networks. The model is stable in dealing with complex flow conditions, and cell wetting/drying processes, as demonstrated by a number of idealised experiments. The model application is demonstrated by applying to a case study in Brazil.
Danguang Huang, Kalanithy Vairavamoorthy, and Seneshaw Tsegaye
American Society of Civil Engineers
With increasing global change pressures (urbanization, climate change etc.) coupled with e xisting un-sustainability factors and risks inherent to conventional urban water management, cities of the future will experience difficulties in efficient decision making on the infrastructure development. Projections of future global change pressures are plagued with uncertainties which cause difficulties when developing urban water infrastructures that are insensitive to these global change uncertainties. In this paper a methodology is presented that generates optimal urban water networks that are adaptable and sustainable under future global change pressures. These flexible systems are characterized by their ability to cope with uncertainties and have the capability to adapt to new, different, or changing requirements. The flexible design tool presented in this paper consists of two major components. The first component is a methodology for developing scenario trees that reflect uncertainties associated with future demand for water. These scenario trees represent the uncertainty envelope associated with demand projections over time. The second component is an optimization model that considers the phased design of the water network, taking into account the likeliness of different demand scenarios over time (as expressed by the scenario trees). The GA based optimization model identifies the optimal staged development of the network that gives the optimal expected value of the network both in terms of costs and benefits. The flexible design tool is then applied to the design of an example network with a design horizon of 30 year. The solution is presented as a phased design in 5 year stages and is compared with a design undertaken in the traditional way. This comparison clearly highlights the benefits and the efficacy of applying flexible design approaches for water systems operating under future uncertainties.