Larry W. Mays

Model for real-time optimal flood control operation of a reservoir system

A methodology and model have been developed for the real-time optimal flood operation of river-reservoir systems. This methodology is based upon combining a nonlinear programming model with a flood-routing simulation model within an optimal control framework. The generalized reduced gradient code GRG2 is used to perform the nonlinear optimization and the simulator is the U.S. National Wheather Service DWOPER code. Application of the model is illustrated through a case study of Lake Travis on the Lower Colorado River in Texas.

Groundwater Resources Sustainability: Past, Present, and Future

With the worldwide depletion of groundwater and the intensified use around the world, particularly in many arid and semi-arid regions for irrigation and municipal use, there is no satisfactory approach to groundwater sustainability. The lack of and miss-management of this valuable resource has not only created serious groundwater pollution problems but has created present and/or future water supply problems. This paper does not present a solution, but instead examines economic ideas such as exhaustible resource theory (over exploitation), and optimization methodologies that can incorporate new ideas of groundwater sustainability, population growth constraints, include both short term and long term consequences, and consider multi-objectives. Concepts of groundwater footprint, recharge, and safe yield are discarded as concepts for measuring groundwater sustainability. The concept of developing a sustainability index that could also be used within the context of optimization is introduced. Also the concepts of traditional knowledge are discussed with the emphasis on the use of these methodologies for both developed and developing regions of the world to achieve groundwater sustainability.

Optimal maintenance scheduling for water distribution systems

Abstract The scheduling of maintenance for water distribution systems is a complex task encompassing a wide range of alternatives. The methodology presented in this paper can consider the major piping alternatives of replacing and cleaning, and relining. It also considers the potential of pumping improvements while accounting for the costs of maintenance, failure and operations for a multiple-period planning horizon. To solve the problem a nonlinear optimization model is linked with a network simulation model. The application showed that the procedure can determine solutions in reasonable times.

Optimal risk-based design of storm sewer networks

Optimal design of sewer network has conventionally been pursued within a deterministic framework. However, such design may be appropriate because of existence of uncertainties affecting the performance of a storm sewer system, e.g., precipitation rate, insufficient data, errors in design equations, and other factors. These uncertainties are systematically evaluated and incorporated in the proposed design of a storm sewer system. The optimal choice of slopes and diameters of the entire sewer network is based on a tradeoff between risk due to potential flood losses and the cost of installation of the sewers. Discrete differential dynamic programming technique is used in the risk-based design.

Ancient water technologies

1. A Brief History of Water Technology during Antiquity: Before the Romans Larry W. Mays 2. Water Technology in Ancient Mesopotamia Aldo Tamburrino 3.Water Technology in Ancient Egypt Larry W. Mays 4. Ancient Greek Lavatories: Operation with Reused Water Georgios P. Antoniou 5. Water Resource Management in Irans Ancient Persepolis Complex Mahdi Moradi- Jalal, Siamak Arianfar, Bryan Karney and Andrew Colombo 6. A Web Based Information System for the Inspection of the Hydraulic Works in Ancient Greece Nikos Mamassis and Demetris Koutsoyiannis 7. A Brief History of Roman Water Technology Larry W. Mays 8. Analysis of the water system of the Roman city of Apamea Benoit Haut and Didier Viviers 9. Water Technology in the Ancient American Societies Larry W. Mays and Yuri Gorokhovich 10. Groundwater Resources and Earthquake Hazards: Ancient and Modern Perspectives Yuri Gorokhovich, and Lee Ullman 11. Lessons from the Ancients on Water Resources Sustainability Larry W. Mays

Development of an Optimization/Simulation Model for Real-Time Flood-Control Operation of River-Reservoirs Systems

Real-time optimal operation models for river-reservoir systems, unfortunately, are not widely available. Such models are still in their infancy perhaps due to the complexity of the application. This paper presents the development and testing of a methodology for determining reservoir release schedules before, during, and after an extreme flood event in real time. The problem is formulated as a real-time optimal control problem in which reservoir releases represent the decision variables. The model consists of five major components: (1) the U.S. Army Corps of Engineers (USACE) Hydrologic Engineering Center - Hydrologic Modeling System (HEC-HMS), which simulates rainfall-runoff processes of watershed systems; (2) the U.S. Army Corps of Engineers Hydrologic Engineering Center - River Analysis System (HEC-RAS) for one-dimensional unsteady flow routing; (3) a reservoir release operation model; (4) a short-term rainfall forecasting model to project rainfall over the next few hours during a rainfall event; and (5) a genetic algorithm (GA) optimizer interfaced with the other components that determine the real time operation of a river-reservoir systems. An example application is used to test the development of the modeling framework, also illustrating the use of such a model. Each model component and its interface in the modeling framework was tested for quality assurance.

The application of simulated annealing to the optimal operation of water systems

The operation of water distribution systems impacts the water quality in these systems. EPA regulations require that water quality be maintained at all points in the system including the point of delivery. Methods to optimize water system operations have been restricted to reducing costs related to pumping and costs related to sizing, construction and/or maintenance of piping while meeting customer demands, pressure limits, and tank operation restrictions. There have been few attempts to optimize water system operations for both hydraulic and water quality performance and they have been restricted to simplified systems. President, Goldman, Toy and Associates, Inc., 1990 W. Camelback Rd., Suite 401, Phoenix, AZ 85015; e-mail: fredg@goldmantoy.com. Prof., Department of Civ. and Envir. Engrg., Arizona State University, Tempe, AZ 85287; email: mays@asu.edu. A new methodology that formulates the water distribution system problem as a discrete time optimal control problem was developed which linked the method of simulated annealing with EPANET for optimal operation of water distribution systems for both water quality and hydraulic performance. Most optimization techniques require the calculation of derivatives, response functions, or other methods that are limited to specific problems. Simulated annealing allows optimization for a variety of objective functions and can consider many modifications to operational conditions without reprogramming of the optimization procedure. The new methodology was applied to two water systems as examples. The northwest pressure zone in Austin, Texas application considered pump operation to

Optimization – Simulation Model for Detention Basin System Design

A model for the design of detention basin systems is presented that interfaces a simulated annealing (SA) optimization procedure with the U.S. Army Corps of Engineer’s Hydrologic Engineering Center - Hydrologic Modeling System (HEC-HMS). The optimization model is based upon the simulated annealing method to optimize the size and location of detention basin system including the outlet structures subject to design constraints. The program is implemented in Visual Basic for Applications (VBA) interfacing the simulated annealing model with the HEC-HMS model using an MS Excel environment. The respective result files are created by using a VBA executed Python script to extract the appropriate data from the HEC-HMS project DSS file after each simulation performed for the SA procedure. Example applications include a single detention basin system and multiple detention basin systems considering two scenarios. Though the implementation requires considerable computational effort with respect to the number of hydrologic simulations, simulated annealing proves to be an effective tool in the optimal design of detention basin systems as compared to traditional standards of practice.

Water Resources Sustainability: Development of a Multiobjective Optimization Model

AbstractThis research investigates the application of multiobjective optimization (MO) modeling to the issue of water resources sustainability, from a water supply standpoint, with specific application to the Prescott Active Management Area (AMA) in Arizona. One unique aspect of the investigation is the development of a method to quantify the nonuse value of groundwater for use in a quantitative optimization model. Another is the incorporation within the model of objectives that include the typically conflicting goals of growth, conservation, and cost minimization. The model is solved using a multiobjective genetic algorithm.

Prediction of Intake Vortex Risk by Nearest Neighbors Modeling

Vortex formation at intakes can cause damage, clogging, reduced flow efficiency, and even loss of life. For practical prediction of vortex risk, engineers often compare expected design parameters with published data by using parameter proximity to evaluate the relative risk of vortex formation. Unfortunately, this procedure is ill-defined, and the resulting risk estimates are highly subjective. In response, a formal equivalent of the data proximity procedure was developed by implementing the nearest neighbors algorithm on available experimental and field data. This database was partitioned and the machine learning parameters adjusted to obtain a stochastic model with maximum predictive accuracy. Unlike the flow parameters and submergence, the approach geometry was not found to be a significant factor in the model, although this may be attributable to data noise and range of tested values. The final model, which excluded the channel approach geometry, fit all vertical intake vortex formation data to within 0.1% error and perfectly fit the horizontal intake data. Probability charts generated from the model show regions of vortex formation and problems more numerous and larger on average than regions of low vortex probability, thus validating consideration of potential vortex formation risk for conservative intake design.