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 Research type Water System Technical Focus Abstract Link with Projects Link with Tools Related policies ID
publications-4521 article 2018 Haag, Sebastian and Haag, Sebastian and Anderl, Reiner and Anderl, Reiner Digital twin – Proof of concept Manufacturing letters 10.1016/j.mfglet.2018.02.006
publications-4522 article 2018 RajratnaKharat and RajratnaKharat and Bavane, Vikas and Bavane, Vikas and Marode, Santosh Jadhao Prof. Roshan and Marode, Santosh Jadhao Prof. Roshan DIGITAL TWIN: MANUFACTURING EXCELLENCE THROUGH VIRTUAL FACTORY REPLICATION 10.5281/zenodo.1493930
publications-4523 article 1984 Maidment, David R. and Maidment, David R. and Parzen, Emanuel and Parzen, Emanuel Time patterns of water use in six Texas cities Journal of Water Resources Planning and Management 10.1061/(asce)0733-9496(1984)110:1(90) Time series of monthly water use data from 6 Texas cities are examined. The time variation of the data may be divided into long memory (on average, 70\% of total variation), short memory (15\%) and residual error (15\%). Long-memory results from trend and seasonal variation. In each city, trend is analyzed by stepwise regression of mean annual water use on population, number of water connections, household income and water prices, in which population is consistently the most significant explanatory variable for trends in water use from year to year. Short-term memory results from autocorrelation and climatic correlation. Climate correlation is strong in the three cities examined in the semi arid High Plains of Texas where if one inch more than mean monthly rainfall or pan evaporation occurs, it results on average in a 10 gpcd (38 Lpcd) change in mean monthly water use (decrease for rainfall, increase for evaporation). In three cities in humid East Texas the response of water use to weather variations is weaker. Confidence limits on modeled water use adequately envelop the response of water use to the droughts experienced by these cities from 1961-1978.
publications-4524 article 1986 Agthe, Donald E. and Agthe, Donald E. and Billings, R. Bruce and Billings, R. Bruce and Dobra, John and Dobra, John L. and Raffiee, Kambiz and Raffiee, Kambiz A Simultaneous Equation Demand Model for Block Rates Water Resources Research 10.1029/wr022i001p00001 This paper examines the problem of simultaneous-equations bias in estimation of the water demand function under an increasing block rate structure. The Hausman specification test is used to detect the presence of simultaneous-equations bias arising from correlation of the price measures with the regression error term in the results of a previously published study of water demand in Tucson, Arizona. An alternative simultaneous equation model is proposed for estimating the elasticity of demand in the presence of block rate pricing structures and availability of service charges. This model is used to reestimate the price and rate premium elasticities of demand in Tucson, Arizona for both the usual long-run static model and for a simple short-run demand model. The results from these simultaneous equation models are consistent with a priori expectations and are unbiased.
publications-4525 article 1989 Billings, R. Bruce and Billings, R. Bruce and Day, W. Mark and Day, W. Mark Demand management factors in residential water use: the southern Arizona experience Journal American Water Works Association 10.1002/j.1551-8833.1989.tb03182.x Two models of residential water demand were run with data from three water utilities in the Tucson, Ariz., metropolitan area to estimate the response of water use to variations in price, household income, and a variety of socioeconomic and climatic variables. The study covered a period when all three utilities experienced substantial reductions in residential water use. All three utilities examined imposed availability-of-service charges, and the largest utility used increasing-block rates and seasonal rates. Because of disagreement in the literature about the proper specification of price under these conditions, demand models were estimated using both the traditional average-price variable and the marginal price plus rate premium. Estimated long-term price elasticities for the combined time-series-cross-section models averaged -0.72, and they varied depending on model specification and time period. Individual demographic district elasticities were also estimated. Several principles of conservation pricing and other aspects of demand management for water utilities are discussed.
publications-4526 article 1990 Boulos, Paul F. and Boulos, Paul F. and Wood, Don J. and Wood, Don J. and Wood, Don J. Explicit calculation of pipe-network parameters Journal of Hydraulic Engineering 10.1061/(asce)0733-9429(1990)116:11(1329) An explicit algorithm is presented for directly determining a variety of design, operating, and calibration parameters for pipe networks. The problem solution is based on the reformulation of the steady‐state network equilibrium equations in terms of specified pipe‐system parameters. Since these equations are nonlinear, the incremental Newton‐Raphson method is used as the basic solution procedure. A continuous variable space is assumed for the various parameters, which are selected to exactly satisfy stated pressure and flow requirements at critical nodes and pipes throughout the pipeline systems for a range of operating conditions. This approach offers a basis for determining the optimum values for the various design, operating, and calibration parameters in the sense that the parameters can be calculated to exactly meet the specified pressure and flow constraints. All types of pipe distribution systems can be considered. The solution space is secured through a well‐arranged interaction between network t...
publications-4527 article 1997 Halhal, D. and Halhal, Driss and Walters, Godfrey A. and Walters, Godfrey A. and Ouazar, Driss and Ouazar, Driss and Savić, Dragan and Savic, Dragan WATER NETWORK REHABILITATION WITH STRUCTURED MESSY GENETIC ALGORITHM Journal of Water Resources Planning and Management 10.1061/(asce)0733-9496(1997)123:3(137) The importance of water distribution network rehabilitation, replacement, and expansion is discussed. The problem of choosing the best possible set of network improvements to make with a limited budget is presented as a large optimization problem to which conventional optimization techniques are poorly suited. A multiobjective approach is described, using capital cost and benefit as dual objectives, enabling a range of noninferior solutions of varying cost to be derived. A structured messy genetic algorithm is developed, incorporating some of the principles of the messy genetic algorithm, such as strings that increase in length during the evolution of designs. The algorithm is shown to be an effective tool for the current optimization problem, being particularly suited both to the multiobjective approach and to problems that involve the selection of small sets of variables from large numbers of possibilities. Two examples are included that demonstrate the features of the method and show that the algorithm performs much better than a standard genetic algorithm for a large network.
publications-4528 article 1999 Grimm, Volker and Grimm, Volker Ten years of individual-based modelling in ecology: what have we learned and what could we learn in the future? Ecological Modelling 10.1016/s0304-3800(98)00188-4
publications-4529 article 1999 Michelsen, An M. and Michelsen, An M. and McGuckin, J. Thomas and McGuckin, J. Thomas. and Stumpf, Donna and Stumpf, Donna Nonprice water conservation programs as a demand management tool Journal of The American Water Resources Association 10.1111/j.1752-1688.1999.tb03615.x : Water providers nationwide are implementing nonprice conservation measures such as education, public information, appliance retrofit and ordinances, with the expectation that these programs will reduce residential water demand. However, little empirical information exists on the effectiveness of nonprice conservation programs in reducing water demand. Previous econometric studies indicate these programs have had minimal impact. We examine the types and number of major nonprice conservation programs that have been implemented during an 11-year period in seven cities in the southwestern United States. A cross sectional, monthly time series residential water demand model, with parameters to control for variation in prices, temperature, precipitation and other factors, was used to empirically investigate the effectiveness of nonprice conservation programs in reducing water demand. We found significant reductions in use ranging between 1.1 percent and 4.0 percent per program. Because of the lack of information, we were unable to distinguish the effectiveness of individual or specific types of programs. Beyond finding that nonprice programs can be effective in reducing demand, questions regarding the efficiency and benefits to be achieved by conservation remain. As a step towards separating and evaluating the effects of individual programs, program benefits and efficiency, we recommend that utilities maintain more detailed and consistent information regarding the implementation of their nonprice programs.
publications-4530 article 2000 Cohen, Reuven and Cohen, Reuven and Erez, Keren and Erez, Keren and ben‐Avraham, Daniel and ben-Avraham, Daniel and Havlin, Shlomo and Havlin, Shlomo Resilience of the internet to random breakdowns Physical Review Letters 10.1103/physrevlett.85.4626 A common property of many large networks, including the Internet, is that the connectivity of the various nodes follows a scale-free power-law distribution, P(k)=ck^-a. We study the stability of such networks with respect to crashes, such as random removal of sites. Our approach, based on percolation theory, leads to a general condition for the critical fraction of nodes, p_c, that need to be removed before the network disintegrates. We show that for a<=3 the transition never takes place, unless the network is finite. In the special case of the Internet (a=2.5), we find that it is impressively robust, where p_c is approximately 0.99.