Scientific Results

This catalogue is obtained by conducting a systematic literature review of scientific studies and reviews related to monitoring, forecasting, and simulating the inland water cycle. The analysis maps scientific expertise across research groups and classifies findings by the type of inland water studied, application focus, and geographical scope. A gap analysis will identify missing research areas and assess their relevance to policymaking.

ID ▲	Type	Year	Authors	Title	Venue/Journal	DOI	Abstract
publications-4391	article	2001	Albert, RΓ©ka and Albert, RΓ©ka and BarabΓ΅si, Albertβ€LΓ΅szlΓ³ and BarabΓ΅si, Albert-LΓ΅szlΓ³	Statistical mechanics of complex networks	Reviews of Modern Physics	10.1103/revmodphys.74.47	The emergence of order in natural systems is a constant source of inspiration for both physical and biological sciences. While the spatial order characterizing for example the crystals has been the basis of many advances in contemporary physics, most complex systems in nature do not offer such high degree of order. Many of these systems form complex networks whose nodes are the elements of the system and edges represent the interactions between them. Traditionally complex networks have been described by the random graph theory founded in 1959 by Paul Erdohs and Alfred Renyi. One of the defining features of random graphs is that they are statistically homogeneous, and their degree distribution (characterizing the spread in the number of edges starting from a node) is a Poisson distribution. In contrast, recent empirical studies, including the work of our group, indicate that the topology of real networks is much richer than that of random graphs. In particular, the degree distribution of real networks is a power-law, indicating a heterogeneous topology in which the majority of the nodes have a small degree, but there is a significant fraction of highly connected nodes that play an important role in the connectivity of the network. The scale-free topology of real networks has very important consequences on their functioning. For example, we have discovered that scale-free networks are extremely resilient to the random disruption of their nodes. On the other hand, the selective removal of the nodes with highest degree induces a rapid breakdown of the network to isolated subparts that cannot communicate with each other. The non-trivial scaling of the degree distribution of real networks is also an indication of their assembly and evolution. Indeed, our modeling studies have shown us that there are general principles governing the evolution of networks. Most networks start from a small seed and grow by the addition of new nodes which attach to the nodes already in the system. This process obeys preferential attachment: the new nodes are more likely to connect to nodes with already high degree. We have proposed a simple model based on these two principles wich was able to reproduce the power-law degree distribution of real networks. Perhaps even more importantly, this model paved the way to a new paradigm of network modeling, trying to capture the evolution of networks, not just their static topology.
publications-4392	article	2001	Downing, Thomas E. and Downing, Thomas E. and Moss, Scott and Moss, Scott and Pahlβ€Wostl, Claudia and Pahl-Wostl, Claudia	Understanding climate policy using participatory agent-based social simulation		10.1007/3-540-44561-7_15	Integrated assessment models (IAMs) have been widely applied to questions of climate change policy--such as the effects of abating greenhouse gas emissions, balancing impacts, adaptation and mitigation costs, understanding processes of adaptation, and evaluating the potential for technological solutions. In almost all cases, the social dimensions of climate policy are poorly represented. Econometric models look for efficient optimal solutions. Decision making perspectives might reflect broadscale cultural theory, but not the diversity of cognitive models in practice. Technological change is often ignored or exogenous, and without understanding of stakeholder strategies for innovation and diffusion. Policy measures are proposed from idealised perspectives, with little understanding of the constraints of individual decision makers. We suggest a set of criteria for IAMs that can be used to evaluate the choice and structure of models with respect to their suitability for understanding key climate change debates. The criteria are discussed for three classes of models-- optimising econometric models, dynamic simulation models and a proposed agent-based strategy. A prototype agent-based IAM is reported to demonstrate the usefulness and power of the agent based approach and to indicate concretely how that approach meets the criteria for good IAMs and to complex social issues more generally.
publications-4393	article	2002	Hallam, Nicholas B. and Hallam, Nicholas B. and West, John R. and West, John R. and Forster, C.F. and Forster, C.F. and Powell, Jennifer and Powell, James C. and Spencer, I and Spencer, I	The decay of chlorine associated with the pipe wall in water distribution systems	Water Research	10.1016/s0043-1354(02)00056-8
publications-4394	article	2003	Todini, E. and Todini, E	A more realistic approach to the β€_x009c_extended period simulationβ€_x009d_ of water distribution networks		10.1201/noe9058096081.ch19
publications-4395	article	2003	Poulakis, Z. and Poulakis, Z. and Valougeorgis, Dimitris and Valougeorgis, Dimitris and Papadimitriou, Costas and Papadimitriou, Costas	Leakage detection in water pipe networks using a Bayesian probabilistic framework	Probabilistic Engineering Mechanics	10.1016/s0266-8920(03)00045-6
publications-4396	article	2003	Dalhuisen, J.M. and Dalhuisen, J.M. and Florax, Raymond J.G.M. and Florax, Raymond J.G.M. and de Groot, H.L.F. and de Groot, Henri L. F. and Nijkamp, Peter and Nijkamp, Peter	Price and Income Elasticities of Residential Water Demand: A Meta-Analysis	Land Economics	10.2307/3146872	This article presents a meta-analysis of variations in price and income elasticities of residential water demand. Meta-analysis constitutes an adequate tool to synthesize research results by means of an analysis of the variation in empirical estimates reported in the literature. We link the variation in estimated elasticities to differences in theoretical microeconomic choice approaches, differences in spatial and temporal dynamics, as well as differences in research design of the underlying studies. The occurrence of increasing or decreasing block rate systems turns out to be important. With respect to price elasticities, the use of the discrete-continuous choice approach is relevant in explaining observed differences.
publications-4397	article	2005	Ostfeld, Avi and Salomons, Elad	Optimal early warning monitoring system layout for water networks security: inclusion of sensors sensitivities and response delays	Civil Engineering and Environmental Systems	10.1080/10286600500308144	Drinking water utilities around the world are vulnerable to various types of terrorist attacks including warfare contamination and bioterrorism. A distribution system comprises water tanks, pipes, pumps, and other components that deliver treated water from treatment plants to consumers. Particularly among large utilities, distribution systems may contain thousands of kilometers of pipes and numerous delivery points, which can be highly vulnerable to a terrorist deliberate contamination injection. This paper extends previous work on optimal early warning monitoring system layout for water networks security by addressing the monitoring stations detection sensitivities and response delays, and the consumer demands and contaminant injected flow rates randomness. The methodology developed is demonstrated on two example applications.
publications-4398	article	2005	Moss, Scott and Moss, Scott and Edmonds, Bruce and Edmonds, Bruce	Sociology and simulation : Statistical and qualitative cross-validation	American Journal of Sociology	10.1086/427320	Agentβ€based simulation modeling enables the construction of formal models that simultaneously can be microvalidated against accounts of individual behavior and macrovalidated against aggregate data that show the characteristics of many socially derived time series. These characteristics (leptokurtosis and clustered volatility) have two important consequences: first, they also appear in suitably structured agentβ€based models where, like real social actors, agents are socially embedded and metastable; second, their presence precludes the use of many standard statistical techniques like the chiβ€square test. These characteristics in timeβ€series data indicate that a suitable agentβ€based model rather than a standard statistical model will be appropriate. This is illustrated with an agentβ€based model of mutual social influence on domestic water demand. The consequences for many frequently used statistical techniques are discussed.
publications-4399	article	2005	Berry, Jonathan W. and Hart, William E. and Phillips, Cynthia A. and Uber, James G. and Walski, Thomas M.	Water Quality Sensor Placement in Water Networks with Budget Constraints		10.1061/40792(173)60	In recent years, several integer programming models have been proposed to place sensors in municipal water networks in order to detect intentional or accidental contamination. Although these initial models assumed that it is equally costly to place a sensor at any place in the network, there clearly are practical cost constraints that would impact a sensor placement decision. Such constraints include not only labor costs but also the general accessibility of a sensor placement location. In this paper, we extend our integer program to explicitly model the cost of sensor placement. We partition network locations into groups of varying placement cost, and we consider the public health impacts of contamination events under varying budget constraints. Thus our models permit cost/benefit analyses for differing sensor placement designs. As a control for our optimization experiments, we compare the set of sensor locations selected by the optimization models to a set of manually-selected sensor locations.
publications-4400	article	2006	Janssen, Marco A. and Janssen, Marco A. and Π_x009e_ΡΡ‚Ρ€ΠΎΠΌ, ΠΠ»ΠΈΠ½ΠΎΡ€ and Ostrom, Elinor	Empirically Based, Agent-based models	Ecology and Society	10.5751/es-01861-110237	There is an increasing drive to combine agent-based models with empirical methods. An overview is provided of the various empirical methods that are used for different kinds of questions. Four categories of empirical approaches are identified in which agent-based models have been empirically tested: case studies, stylized facts, role-playing games, and laboratory experiments. We discuss how these different types of empirical studies can be combined. The various ways empirical techniques are used illustrate the main challenges of contemporary social sciences: (1) how to develop models that are generalizable and still applicable in specific cases, and (2) how to scale up the processes of interactions of a few agents to interactions among many agents.