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-4571	article	1999	Albert, RΓ©ka and Albert, RΓ©ka and Jeong, Hawoong and Jeong, Hawoong and BarabΓ΅si, Albert LΓ΅szlΓ³ and BarabΓ΅si, Albert-LΓ΅szlΓ³	Diameter of the World-Wide Web	Nature	10.1038/43601	Despite its increasing role in communication, the World-Wide Web remains uncontrolled: any individual or institution can create a website with any number of documents and links. This unregulated growth leads to a huge and complex web, which becomes a large directed graph whose vertices are documents and whose edges are links (URLs) that point from one document to another. The topology of this graph determines the web's connectivity and consequently how effectively we can locate information on it. But its enormous size (estimated to be at least 8Γ—108 documents1) and the continual changing of documents and links make it impossible to catalogue all the vertices and edges.
publications-4572	article	1998	Redner, S. and Redner, Sidney	How popular is your paper? An empirical study of the citation distribution	European Physical Journal B	10.1007/s100510050359	Numerical data for the distribution of citations are examined for: (i) papers published in 1981 in journals which are catalogued by the Institute for Scientific Information (783,339 papers) and (ii) 20 years of publications in Physical Review D, vols. 11-50 (24,296 papers). A Zipf plot of the number of citations to a given paper versus its citation rank appears to be consistent with a power-law dependence for leading rank papers, with exponent close to -1/2. This, in turn, suggests that the number of papers with x citations, N(x), has a large-x power law decay \(N(x) \sim {x^{ - a}}\), with \(a \approx 3\).
publications-4573	article	1997	Axelrod, Robert and Axelrod, Robert	Advancing the art of simulation in the social sciences	Complexity	10.1002/(sici)1099-0526(199711/12)3:2<16::aid-cplx4>3.0.co;2-k	Advancing the state of the art of simulation in the social sciences requires appreciating the unique value of simulation as a third way of doing science, in contrast to both induction and deduction. This essay offers advice for doing simulation research, focusing on the programming of a simulation model, analyzing the results and sharing the results with others. Replicating other peopleβ€™s simulations gets special emphasis, with examples of the procedures and difficulties involved in the process of replication. Finally, suggestions are offered for building of a community of social scientists who do simulation.
publications-4574	article	1998	Bush, Cheryl A. and Bush, Cheryl A. and Uber, James G. and Uber, James G.	Sampling Design Methods for Water Distribution Model Calibration	Journal of Water Resources Planning and Management	10.1061/(asce)0733-9496(1998)124:6(334)	Field sampling is sometimes performed to support modeling activitiesβ€”specifically, to estimate the parameters of a mathematical model or, more accurately, to calibrate the model. In this case, a relevant question for field samplings design is β€_x009c_how to maximize the confidence in estimated parameter values, given a level of sampling effort?β€_x009d_ We approach this question using established ideas in parameter estimation and sampling design theory and propose general sensitivity-based methods to rank the locations and types of measurements for estimating the parameters of a water distribution network model. The proposed methods are suboptimal, yet practical, and are applied to select good tracer and pressure measurement locations for estimating pipe roughness coefficients. These particular results suggest that, when compared to pressure measurements, tracer measurements can be informative for calibrating network hydraulic parameters but one must take more care in selecting their location. Using the proposed methods...
publications-4575	article	1999	HΓ¶glund, Lena and HΓ¶glund, Lena	Household demand for water in sweden with implications of a potential tax on water use	Water Resources Research	10.1029/1999wr900219	The purpose of this paper is to estimate empirically the effects of a water tax on water use and on the size and stability of the tax revenues. A tax exceeding value-added tax can be motivated on efficiency grounds when there are environmental external costs of water use and when water is a scarce resource. A household demand function for water is estimated using community level data for 282 (out of 286) Swedish communities studied annually over the period 1980β€“1992. Static and dynamic demand functions are estimated using panel data methods. The results show a long-run price elasticity of β’0.10 in marginal price models and β’0.20 in average price models. The findings imply that a tax of 1 Swedish Kronor (SEK) mβ’3 of water used (corresponding to a 5\% increase in the mean average price) would generate βΌ600 million SEK in tax revenues per year when levied on all households in Sweden. The water consumption would, however, only be reduced by βΌ1\%.
publications-4576	article	2001	Lansey, Kevin and Lansey, Kevin E and Elshorbagy, Walid and El-Shorbagy, W. and Elshorbagy, Walid and Ahmed, Iftekhar and Ahmed, Iftekhar and Araujo, J. B. and Araujo, J. and Haan, C. T. and Haan, C. T.	Calibration assessment and data collection for water distribution networks	Journal of Hydraulic Engineering	10.1061/(asce)0733-9429(2001)127:4(270)	Calibration of a water distribution network is intended to develop a model that mimics field conditions under a range of demand distributions. In this paper, a three-step calibration procedure is developed that considers the uncertainties in measurement and estimation and provides a measure of the quality of the calibration. The approach can also be used to identify preferable conditions for data collection. The procedure's steps are parameter estimation, calibration assessment, and data collection design. Parameter estimation considers input uncertainty and the resulting uncertainty in model parameters. Calibration assessment analyzes the propagation of the parameter errors on model predictions. The trace of the covariance matrix of the predictive heads is used to measure the model uncertainty. Based on this uncertainty and using a sensitivity-based heuristic analysis, data collection experiments can be designed for systemwide tests and critical pipe for individual pipe tests. An example system is analyz...
publications-4577	article	2000	Clark, Robert M. and Deininger, Rolf A.	Protecting the Nation's Critical Infrastructure: The Vulnerability of U.S. Water Supply Systems	Journal of Contingencies and Crisis Management	10.1111/1468-5973.00126	Terrorism in the United States was not considered a serious threat until the second half of the 1990s. However, recent attacks both at home and abroad have forced government planners to consider the possibility that critical elements of the U.S. infrastructure might in fact be vulnerable to terrorism. The potential for chemical or biological contamination of water supply systems exists along with the possibility that such systems might be sabotaged. This article reviews the threat of biological and chemical compounds in relation to the characteristics of water supply systems. Vulnerability of such systems to terrorist attacks is examined, as well as possible physical and chemical countermeasures that could be applied. A case study is presented of an accidental contamination event that illustrates the difficulty of tracking such events in a drinking water system. It can be concluded that municipal water supplies are vulnerable. However, appropriate physical planning of such systems, including contingency back-up with separate water lines for emergencies, coupled with proactive monitoring, will significantly increase security in the face of possible terrorist attacks.
publications-4578	article	1999	Harmant, Ph. and Nace, A. and Kiene, L. and Fotoohi, F.	Optimal Supervision of Drinking Water Distribution Network		10.1061/40430(1999)52	In the context of the self supervision of drinking water distribution systems, network managers have to carry out regular sampling campaigns. These samplings give a selective overview of quality but may suffer from a lack of representativity. Considering that a rational approach of the choice of sampling sites would improve the control of the quality in the network, the CIRSEE has developed a new strategy of selection of sampling sites. This strategy is based on an algorithm derived from a publication of Lee and Deininger. Modeling of the hydraulic behavior of the network is a compulsory step to street optimal sampling points. A covering matrix, deduced from PiccoloΒ® hydraulics modeling (developed by SAFEGE), defines the link between each network node. Afterwards, the algorithm selects the most representative points (for sampling or on line monitoring) in terms of consumption and of water degradation (function of pipe diameter and water retention time).
publications-4579	article	2001	Pastor-Satorras, Romualdo and Pastor-Satorras, Romualdo and VΓ΅zquez, Alexei and Vazquez, Alexei and Vespignani, Alessandro and Vespignani, Alessandro	Dynamical and Correlation Properties of the Internet	Physical Review Letters	10.1103/physrevlett.87.258701	The description of the Internet topology is an important open problem, recently tackled with the introduction of scale-free networks. We focus on the topological and dynamical properties of real Internet maps in a three-year time interval. We study higher order correlation functions as well as the dynamics of several quantities. We find that the Internet is characterized by nontrivial correlations among nodes and different dynamical regimes. We point out the importance of node hierarchy and aging in the Internet structure and growth. Our results provide hints towards the realistic modeling of the Internet evolution. Complex networks play an important role in the under- standing of many natural systems (1,2). A network is a set of nodes and links, representing individuals and the interactions among them, respectively. Despite this simple definition, growing networks can exhibit a high degree of complexity, due to the inherent wiring entanglement occur- ring during their growth. The Internet is a capital example of growing network with technological and economical relevance; however, the recollection of router-level maps of the Internet has received the attention of the research community only very recently (3-5). The statistical analysis performed so far has revealed that the Internet ex- hibits several nontrivial topological properties (wiring redundancy, clustering, etc.). Among them, the presence of a power-law connectivity distribution (6,7) makes the Internet an example of the recently identified class of scale-free networks (8). In this Letter, we focus on the dynamical properties of the Internet. We shall consider the evolution of real In- ternet maps from 1997 to 2000, collected by the National Laboratory for Applied Network Research (NLANR) (3). In particular, we will inspect the correlation properties of nodes' connectivity, as well as the time behavior of several quantities related to the growth dynamics of new nodes. Our analysis shows dynamical behavior with dif- ferent growth regimes depending on the node's age and connectivity. The analysis points out two distinct wiring processes: the first one concerns newly added nodes, while the second is related to already existing nodes increasing their interconnections. A feature introduced in this pa- per refers to the Internet hierarchical structure, reflected in a nontrivial scale-free connectivity correlation function. Finally, we discuss recent models for the generation of scale-free networks in the light of the present analysis of real Internet maps. The results presented in this Letter could help develop more accurate models of the Internet.
publications-4580	article	2000	Maslia, Morris L. and Maslia, Morris L. and Maslia, Morris L. and Maslia, Morris L. and Sautner, Jason B. and Sautner, Jason B. and Sautner, J. B. and Aral, Mustafa M. and Sautner, J. B. and Aral, Mustafa M. and Aral, Mustafa M. and Aral, Mustafa M. and Reyes, Juan JosΓ© and Reyes, Juan JosΓ© and Reyes, J. J. and Reyes, J. J. and Abraham, John and Abraham, John and Abraham, John E. and Williams, Robert C. and Abraham, John E. and Williams, Robert C. and Williams, Robert and Williams, Robert	Using Water-Distribution System Modeling to Assist Epidemiologic Investigations	Journal of Water Resources Planning and Management	10.1061/(asce)0733-9496(2000)126:4(180)	An epidemiologic study of childhood leukemia and central nervous system cancers that occurred in the period 1979 through 1996 in Dover Township, N.J., is being conducted. Because groundwater contamination has been documented historically in public- and private-supply wells, there is the possibility of exposure through this pathway. The Dover Township area has been primarily served by a public water supply that relies solely on groundwater; therefore, a protocol has been developed for using a water-distribution model such as EPANET as a tool to assist the exposure assessment component of epidemiologic investigation. The model is being used to investigate the question of human exposure to groundwater contaminants. Because of the unavailability of historical data, the model was calibrated to the present-day (1998) water-distribution system characteristics. Pressure data were gathered simultaneously at 25 hydrants throughout the distribution system using continuous recording pressure data loggers during 48 h tests in March and August 1998. Data for storage tank water levels, system demand, and pump and well status (on/off) were also obtained. Field data gathering procedures, calibration results, and water-quality simulation using a naturally occurring element (barium), as well as an analysis indicating the percent of water originating from points of entry to the water-distribution system for 1998 conditions, are presented.