Journal of Water Resources Planning and Management

A compendium of several important articles on the application of computerized decision support systems (DSS) in water resources management is presented. The articles cover software development, hardware selection, data acquisition and control, successes, pitfalls, and documentation of the benefits and values of these systems for a wide variety of applications, on both a small and large scale. DSSs are described for hydropower system operation, power load dispatch, computerized training simulators, center pivot irrigation systems, advanced supervisory data acquisition and control for transbasin diversion projects, large‐scale water supply systems, and operation of complex multipurpose, multireservoir systems. The conclusions from this experience base is that well‐planned computerized DSSs succeeded in: (1) Reducing operational costs; (2) improving system efficiency and productivity; (3) handling tasks previously considered infeasible; and (4) increasing system reliability.

A water resources management decision support system (WRMDSS) consists of integrated computer hardware and software packages readily usable by managers as an aid for making implementation and operations decisions. WRMDSSs allow incorporation of operator judgment into the analysis process, thus providing for man‐machine synergism. The state‐of‐the‐art of WRMDSSs is examined through a review of a number of examples, including microcomputers, flash‐flood warning and regional water‐monitoring systems, water supply and reservoir operating systems, computer‐aided planning, and expert systems. Microprocessor technologies, increasing computer main memory capabilities at decreasing costs, distributed and parallel processing computational methods, integrated system modeling software packages, and artificial intelligence techniques are the driving forces tending to enhance the development and successful implementation of WRMDSSs. Continued development is expected with the potential for enhancing system operational efficiencies and improving confidence in the computer‐based planning process.

Interactive computer simulation is presented as an off‐line decision support tool for training operators of complex water resource systems to define effective operational policy. The ability of the operator or analyst to interact with a system model throughout the simulation process is documented, along with the potential for including intangible aspects of system operation directly into the analysis. Interactive simulators are currently being used by the Western Area Power Administration for training system operation personnel. A case study is also reviewed in which operational guidelines were developed for a three‐reservoir system involving various physical, economic, and legal constraints.

A dynamic programming optimization technique has been applied to three case studies involving hydropower scheduling. Each involved the analysis of an operating strategy for a different time perspective, i.e., instantaneous, hourly, and monthly time frames. The case studies included: (1) The optimal instantaneous scheduling of hydropower units, with different generating characteristics to maximize overall plant efficiency; (2) the optimal hourly scheduling of hydropower generation between two hydrologically linked power plants to maximize overall daily/weekly system efficiency; (3) the optimal monthly scheduling of hydropower generation to minimize the purchase cost of imported power supply subject to a time‐of‐day rate structure. The case studies have shown that optimization techniques can be successfully implemented to gain insight into complex operating strategies.

Microcomputers can improve the management of center pivot sprinkler systems by providing recommendations for irrigation scheduling and selection of the most economical pump combinations. When linked with radio telemetry systems, multiple pivots and pumps can be monitored and controlled from a single location and interfaced with load control programs. Irrigators that can take advantage of the possible savings in labor and pumping costs can justify the necessary investment in a monitoring and control system.

The Windy Gap Project consists of a diversion dam on the Colorado River, a 600 cfs $\left(17m^3{S}^{-1}\right)$ pumping plant, and 30,000 ft (914.4 m) of 108‐in. (2.7‐m) diameter pipeline. The purpose of the project is to divert and transport water from the Colorado River Basin to the Colorado‐Big Thompson (C‐BT) system fqr storage and delivery to users in the South Platte River Basin. Sophisticated compromise agreements were developed to meet the legal, political, social, institutional, and environmental requirements to build the project; as a result, the operations control strategy is complex and practically impossible to operate by conventional supervisory control systems. A state‐of‐the‐art computer based supervisory control and data acquisition (SCADA) system was developed to operate the Windy Gap Project. The SCADA system.is an anticipatory closed loop control system which requires a minimum of human interaction and operates in a real time environment. The basic objective of the SCADA system is to maximize the amount of water diverted while minimizing power cost and meeting the constraints as a result of the compromise agreements.

The Central Arizona Project (CAP), one of the nation's largest water conveyance systems, is designed to deliver much of Arizona's allotment of Colorado River water for municipal, industrial, and agricultural uses in central and southern Arizona. The size and nature of the CAP dictates the use of a computer‐based programmable master supervisory control (PMSC) system as the primary means of operating the aqueduct. A dual‐computer master station is connected to remote terminal units (RTUs) located at each pumping plant, checkgate, and turnout. Through the RTUs, the master station can send instructions to, and receive information from, any point along the • aqueduct. Complex scheduling models generate pump, checkgate, and turnout schedules for the entire aqueduct system. These scheduling models are based on a constant volume philosophy of operation to keep the system responsive to changes in demands. Optimization models can modify these schedules to take advantage of the less expensive off‐peak power costs. The PMSC will also monitor the aqueduct depths and flows measured in the field and compare them to those predicted in the scheduling models. If a large enough divergence occurs, the dispatcher is alerted and predetermined reaction procedures are implemented to shut down or stabilize the aqueduct.

The Lower Colorado Region, U.S. Bureau of Reclamation (Reclamation), is responsible for maintaining and operating Hoover, Davis, and Parker Dams, and the appurtenant reservoirs and powerplants. Operation of this dam and reservoir system is governed by a complex body of congressional acts, a Supreme Court decree, an international treaty, and interstate agreements that have come to be known as the “Law of the River.” Reclamation uses three computer models for decision support purposes ranging from scheduling hourly release rates to planning future monthly and seasonal operations. A computer model called the “24‐month study” is used for planning monthly and seasonal operation of the reservoir and powerplant system. Another model is used to plan and schedule releases for downstream water delivery, energy generation, and flood control requirements on a daily and weekly basis. Finally, Reclamation water schedulers use the Supervisory Control and Data Acquisition (SCADA) computer model of the Western Area Power Administration to automatically control hourly releases for the next 24‐hr day and for same‐day changes at Davis and Parker powerplants.

The Tennessee Valley Authority (TVA) is currently making significant use of computers and associated models for decision support in managing and operating their large system of reservoirs and power facilities. Current uses include assistance in daily operation of the reservoir system, in which computers are used to collect data and execute essential operational programs. This system has allowed collection and processing of a broader scope and greater quantity of data, increased accuracy and accessibility to data, reduced tedious manual computations, and has provided more rapid evaluation of a large number of operational alternatives, all at reasonable cost. This results in a better information base for decision making, more rapid response to system changes, and better operational control. A key factor in the success of the implementation of the computer support system has been the close working relationship between the system developers and the operational staff. A number of computer models are also employed for operational planning, hydrodynamic modeling of rivers and reservoirs, water quality evaluation, and hydropower system optimization.