Quantification of the amount of redundancy in a looped water-distribution network is necessary in order to compare different designs and to use an optimization approach in the design of the system. In this work, redundancy is quantified using the expected shortage due to failure of individual pipes as a surrogate measure of reliability that permits incorporation of some considerations of frequency, duration, and severity of damage. Based on this surrogate, a gradient-modified linear-programming model is developed for minimum-cost design subject to reliability constraints. The model constrains the shortage at each node in the network to be less than or equal to some specified fraction of demand. A solution approach is proposed to overcome computational complexity, and is shown to bring practical-sized network solutions within reach. The model is used to explore the trade-off between cost and reliability. An extension of the algorithm considers storage tanks within the system.

The operation policy of Lake Shelbyville, Illinois has been modified several times in the past 20 years due to unusual weather conditions and changes in basin-wide water resources development. A modified stochastic dynamic programming (SDP) model, which accounts for the unrepeatable agricultural and property damages and improves the accuracy of these damage estimates, is used to evaluate the performance of Lake Shelbyville. The optimal pool levels in the summer months are found to be 2-5 ft lower than the current target level of 599.7 ft. The expected damages in the model increase by 9% when a penalty function is used to force the summer pool to the current target. Moreover, it would take more than one month for Lake Shelbyville to resume the summer pool from the winter drawdown. A transition period of at least two months for lake levels between winter and summer appears warranted.

This paper describes the use of a computer‐based environment to facilitate engineering decision‐making tasks. A prototype system is developed as an exploration tool and as a demonstration of the techniques and principles proposed for improving the effectiveness of decision‐making analysis tasks in ground‐water resources management. Several mathematical techniques, a modeling language, graphic displays, and a friendly interactive user interface are used. The mathematical techniques are: (1) A finite‐element method for ground‐water simulation modeling; (2) linear programming; (3) a new method for obtaining the exact non‐inferior set of a multicriterion problem; and (4) a modeling‐to‐generate‐alternatives (MGA) approach for generating potential alternatives. The modeling language is designed to relieve the analyst of the burden of formatting a general mathematical model for solution using existing mathematical programming packages. The graphic displays provide visual data for ease of data manipulation and effective comparison, and the friendly interactive user interface is designed for engineers who are not necessarily computer experts.

In developing management programs to regulate point sources of waterbomewaste, it may be convenient or even necessary to subdivide the dischargers into groups. For simplicity and effectiveness in meeting water quality goals, it is desirable that the regulatory decisions governing one group of dischargers be minimally influenced by those governing other groups. One way to accomplish this is to separate the watercourse into sets of water quality checkpoints such that each set of checkpoints is associated with a group of dischargers and the effect of the dischargers excluded from a given group upon the checkpoints associated with that group is small. This paper presents a quantitative method for effecting such groupings. The method minimizes the impacts of the dischargers included in a group on checkpoints associated with other groups of dischargers. The method is illustrated using data for several river basins, viz., the Lower Fox River in Wisconsin, the Willamette River in Oregon, and the Mohawk River in New York.

The modern engineering curriculum has evolved to be heavily weighted with science and analysis. Recent concern with the need for instruction in design has led to the introduction of capstone design courses. These courses give the student an opportunity to produce a design, using the scientific principles and analytic methods learned previously. However, students are often thrown into such a course with little preliminary instruction on design methods. Though much of our early understanding of design consisted of broad generalities combined with sets of unrelated, uncodified tips and pointers, there is now a growing body of rigorous knowledge, first suggested 20 years ago, that might be called the science of design. This material is primarily related to techniques for generating, evaluating, and selecting among alternatives. Development of this science must be continued, but its incorporation into the curriculum should not wait for its perfection. Many of its components can and should be taught now, preparing students to undertake capstone design courses.

Several models that can be used to optimally size water distribution pipes were applied to a hypothetical system. The results are summarized in this paper. The models produced solutions with costs that were within 10% of one another, although the solutions were quite different. While the models were helpful in sizing pipes, some manual calculations and a good deal of engineering judgment were required to apply them.

One complex aspect of environmental planning is the stochastic planning nature of environmental impacts. Planners can evaluate alternatives more fully if the stochastic impacts of various alternatives are incorporated into the analyses. Chance‐constrained modeling techniques that are currently applied to real problems cannot incorporate many stochastic environmental impacts because of random variables that are non‐normal and statistically dependent. In addition, confidence limits of distribution parameters cannot be reflected in solutions. The planning technique proposed in this paper uses linear programming and simulation interactively to resolve these difficulties. The technique is demonstrated using a model that selects power plant sites to fulfill two planning objectives: (1) satisfaction of air quality standards; and (2) minimization of the costs of flue gas treatment and electrical transmission. The stochastic environmental impacts that must be controlled are the SO2 impacts from power plants. Relying on the nonparametric method of order statistics, this modeling technique can incorporate random variables of any distribution. Furthermore, confidence limits selected by the model user are obtained. This modeling technique is applicable to any environmental planning problem where the stochastic environmental impacts can be modeled with impact coefficients.

The role of computers as instructional equipment is discussed. It is argued that general purpose software tools (e.g., spreadsheets, equation solvers) significantly and qualitatively change the way in which students (and professional engineers) can think about problems. For this reason, ability to use the personal computer is not merely an educational “end‐product,” it is a necessary step in further learning of engineering principles. Mere “computer literacy” is not enough; the student must be comfortable with the use of the machine as part of his everyday learning process. Ready access to such computers therefore becomes of major importance in engineering education.

A simplified method is proposed for analyzing multiperiod design of regional wastewater systems and other systems possessing a similar network flow structure. The primary objective of the method is generation of multiperiod locations and facility expansion timings. The method is based on several simplifying assumptions. The solution procedure involves a branch and bound algorithm specifically developed for integrating a set of solutions obtained using the initial design flow with a set of solutions obtained using the terminal design flow. A method for comparing the generated multiperiod alternatives is also proposed. The usefulness of the method is demonstrated, using as an example a hypothetical regional waste water system. A Fortran program was written to implement the method. The program is not in a form that would permit its transfer, but interested readers may contact the first author.

Linear programming gradient (LPG) method is an important method for the optimum design of looped water distribution systems, but the complex algorithm and slow convergence restrict its applications. In this paper, the design of the looped water distribution system is considered as a linear programming with variable coefficients. The derivatives of the cost with respect to pipe flows for water distribution system are deduced accurately for the first time. An efficient iterative algorithm for searching the optimum pipe flows is developed. An example is presented. It is shown that the new algorithm has better convergence than present algorithms

Water Resources ResearchVolume 15, Issue 6 p. 1651-1654 CommentariesFree Access Comment on ‘Design of optimal water distribution systems’ by E. Alperovits and U. Shamir G. E. Quindry, G. E. QuindrySearch for more papers by this authorE. D. Brill Jr., E. D. Brill Jr.Search for more papers by this authorJ. C. Liebman, J. C. LiebmanSearch for more papers by this authorA. R. Robinson, A. R. RobinsonSearch for more papers by this author G. E. Quindry, G. E. QuindrySearch for more papers by this authorE. D. Brill Jr., E. D. Brill Jr.Search for more papers by this authorJ. C. Liebman, J. C. LiebmanSearch for more papers by this authorA. R. Robinson, A. R. RobinsonSearch for more papers by this author First published: December 1979 https://doi.org/10.1029/WR015i006p01651Citations: 39AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat References Alperovits, E., U. Shamir, Design of optimal water distribution systems, Water Resour. Res., 136, 885–900, 1977. Citing Literature Volume15, Issue6December 1979Pages 1651-1654 ReferencesRelatedInformation

Alternative effluent charge programs are examined with regard to cost, charge payments, financial burden, and punitive effects. These efficiency and equity issues are evaluated for constant unit charge programs and for effluent charge schedule programs; the latter are found to reduce the charge payments and the financial burden significantly. Example charge schedule solutions are also shown to compare favorably to the corresponding direct regulation solutions.

The management of river basins has received wide attention in the last 10 years but few quantitative studies have been made. The management approach used for maintaining water quality in a river has been mainly the use of effluent or stream standards. Models also have been developed to determine the quality of effluent, which, when discharged, will meet the preset stream standard. Al though the stream standard seems to be a direct approach, as expressed by Liebman and Lynn,1 the setting of a stream standard leaves unanswered the following question: If several upstream plants each contribute to the depres sion of stream quality below the standard at some downstream point, which plant or plants shall be required to provide additional waste treatment and to what degree? The effluent standard, on the other hand, attempts to answer the question partly for a given set of stream standards. However, the question of equity still remains complicated. This simple basic problem, together with many others, has led to the concept of regional basin manage ment. One of the most important objectives of regional authority is to determine optimum cost effectiveness in obtaining the desired water quality and this objective has led to the need for the development of mathematical decision models to help the basin authorities in the planning and implementation of the best water quality control program from the various alternatives available at a time. There are two sets of decision models that consider regionalization, namely, facility-loca tion decisions and degree-of-treatment deci sions. The first set of decisions determines the location and the assignment of waste sources to regional treatment and the second set of decisions determines the degree of waste reduction to be provided by each facility. The scope of this paper falls within the second type of decision making. The paper provides a stochastic programming model that has the objective of minimizing the total operating cost of biochemical oxygen demand (bod) removal by determining the degree of removal required at each treatment facility without violating the desired dissolved oxygen (do) standards in the stream. The stochastic pro gramming model also includes a reliability parameter that provides an economic tradeoff associated with reliability for a desired water quality standard in a stream.

A dynamic programming model is developed that finds the optimal allocation of land uses to maximize economic rent to land net of flood damage. The model specifically considers the impact of upstream development on downstream flood levels and the impact of flood-plain development on the amount of damage for given flood levels. An efficient, but elementary, routing procedure is developed to meet the requirements of the dynamic programming model. The model is demonstrated on realistic data for a watershed with 42 subbasins and eight land-use categories. This test problem is solved in several trials, each trial requiring about 30 sec of computing time. The solutions appear to be stable despite the artificial discretization of flood flows. The model is useful for exploring the relationships among land use decisions and flood damages and for identifying target land use patterns for particular watersheds.

The theory and procedure of an heuristic algorithm that routes a known number of solid waste collection vehicles on a street network is presented. The network is assumed to be planar and connected, consisting of undirected streets. Each street has a travel cost and solid waste load associated with it. The purposes of the procedure are to determine collection districts. The districts must be such that the sum of solid waste loads within each district does not exceed vehicle capacity. Since the vehicle will necessarily traverse some streets where collection is not required and retraverse other streets more times than necessary for collection, the proposed algorithm attempts to minimize the sum of travel costs for these retraced streets. The algorithm determines districts and tours simultaneously. For each tour it lists a sequence of streets and specifies whether the street is merely traveled or also serviced.

NetworksVolume 7, Issue 1 p. 89-92 Article An improvement of Orloff's general routing problem J. W. Male, J. W. Male Illinois Institute of Technology Chicago, IllinoisSearch for more papers by this authorJ. C. Liebman, J. C. Liebman University of Illinois Urbana, IllinoisSearch for more papers by this authorC. S. Orloff, C. S. Orloff University of California Berkeley, CaliforniaSearch for more papers by this author J. W. Male, J. W. Male Illinois Institute of Technology Chicago, IllinoisSearch for more papers by this authorJ. C. Liebman, J. C. Liebman University of Illinois Urbana, IllinoisSearch for more papers by this authorC. S. Orloff, C. S. Orloff University of California Berkeley, CaliforniaSearch for more papers by this author First published: Spring 1977 https://doi.org/10.1002/net.3230070107Citations: 5AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume7, Issue1Spring 1977Pages 89-92 RelatedInformation