Research
Urban Water Systems
My research experience has been focused on urban water supply systems. I use complex adaptive systems methods and interdisciplinary approaches to investigate urban water system resilience and sustainability.
​
I have two lines of research, in which I address urban water systems as an example of social-ecological-technological systems (SETS), a type of coupled systems in which human-nature interactions are mediated through built infrastructure and social institutions.
My first line of research is focused on understanding how different SETS elements and their interactions contribute to the functioning and dynamics of urban water systems and the services they provide to citizens. By investigating urban water systems as SETS, we can identify bottlenecks in water system functioning through a wholistic analysis that combines water resources, built infrastructures, finances, governance institutions and characteristics of the urban community. Furthermore, we can analyse the resilience of water system services to a range of different types of shocks stemming from natural hazards, such as climate change impacts, socioeconomic and political risks, or infrastructure interactions. It also allows us to create scenarios of interventions and potential future trajectories.
​
My second line of research is focused on the sustainability of urban water systems. Sustainability is about balancing ecological and societal needs – in space (both locally and globally) and over time (across generations). The assessment of sustainability is complicated by the fact that tradeoffs are easily obscured – what seems locally sustainable can have unintended consequences across time and space, and what is sustainable to some may be unjust to others. In this context, I am exploring a variety of avenues to investigate urban water system sustainability locally and at present – for example by assessing the protection of water quantity and quality that is achieved through fair and “water-sensitive” allocation mechanisms, policies, technologies, and urban designs, as well as water-sensitive use behavior of citizens, industries, and farming practices. From a global perspective, I approach urban water sustainability through the lens of indirect water use and virtual water. This research links urban water systems to Planetary and Earth System Boundaries, as well as to other sectors (e.g., energy and food systems) through supply chains and cascading effects of local water management decisions across space and time.
​
Urban Social-Ecological-Technological Systems (SETS)
Life in the city - the way people live, work, interact, their identity, and values - are shaped through three-way feedbacks between the natural and built environment, the governance system, and civil society. This is illustrated in the figure below.
The elements of this urban social-ecological-technological system (SETS) coevolve, and result in different types of cities with varying levels of livelihood security, resilience, and sustainability, and different urban cultures. We investigate the different elements of these urban SETS, and how they dynamically interact to create a diversity of city types. The framework shown in the figure sets the context for my current research agenda on urban sustainability.
​
The interdependencies between urban resource management, bottom-up and top-down processes, and power relations among actors shape urban sustainability transformations, as we discussed in a recent article [11] (published with Sara Constantino, Simon Levin, Miguel Centeno and Elke Weber at Princeton University, and Thomas Elmqvist at the Stockholm Resilience Center).
With Suresh Rao (Purdue University), Dietrich Borchardt (Helmholtz Centre for Environmental Research), Jim Jawitz (University of Florida), and others, I have looked at different types of cities from the perspective of their water supply systems and created frameworks [10,8] and modeling studies [9] that integrate the natural, engineered, and human elements involved in providing water supply services, and compare them across cities. Our current work aims to simplify these approaches, so that they can be easily applied for larger, perhaps even global urban studies.
​
Case studies
To ensure that the research methods and results are grounded in, and might eventually be useful for urban planning, decision-making, and management, we work on a case study basis. Amman (Jordan) was the main case study for my PhD research. I have also worked in Ulaanbaatar (Mongolia) and Chennai (India), and I have recently done some research on New York City [12]. The figure below illustrates the kind of work involved in this case study research, which uses the SETS frameworks mentioned above for urban water supply systems [10,8].
​
Data is collected and analyzed for each of these five "capitals", and then integrated to better understand the system functions and dynamics (e.g. service provision), which results from the capital interaction within the urban SETS. A combination of systems approaches, spatial analyses, and network studies are applied as tools for analysis.
​
Complex network analysis of urban infrastructures
Urban infrastructure networks are designed to serve specific urban services and are implemented according to engineering principles. They have traditionally been regarded as structurally and functionally different from natural networks, such as rivers, trees, or neural networks in the brain. Our research shows that when considering functional topologies of urban infrastructure networks they follow many of the same features as natural networks, especially regarding power-law scaling [2-4]. Understanding these underlying, unifying principles makes it easier to identify vulnerabilities of these networks, and helps inform their re-design. This research was carried out within my PhD lab in Suresh Rao's group at Purdue University with collaborators Chris Klinkhamer, Soohyun Yang, Xinyuan Zhang, Jonatan Zischg, and several others.
​
