Journal of Water Resources Planning and Management

The need to detect anthropogenic impacts in the natural environment has increased interest in the design of cost‐effective environmental monitoring networks. A variety of statistical models have been proposed for this purpose. This paper examines four statistical models, with varying degrees of complexity, used to represent the underlying characteristics of potential impacts. The models are incorporated into an optimization procedure used to select cost‐effective designs. Aquatic monitoring data from a nuclear power plant are used to test the robustness of the statistical models, analyze their sensitivity to input parameters, and determine the circumstances that require the use of more complex statistical models to design effective monitoring programs.

The Galloway Project has presented the states on the Colorado River with a proposal requiring a new definition of rights under the Colorado River Compact. These proposals have caused several agencies and states to reevaluate the Colorado River Compact, and to reconsider their present position on the meaning of the terms that have been defined. The Galloway Project proposal is causing a new consideration of water leasing, states rights, state politics, and interstate sales of water.

A real‐time flood management (forecasting) model is developed for flood operation of the Lower Colorado River‐Highland Lake System in Texas. This model combines techniques for one‐dimensional unsteady flow routing, rainfall‐runoff modeling, graphical display capability, and interactive software capability. Unsteady flow routing is performed using the United States National Weather Service DWOPER model. The model allows for specification of alternative future precipitation and river‐level scenarios and operational controls in addition to real‐time river levels, reservoir levels, and rainfall.

Electronic spreadsheet software developed for microcomputers provides a means by which an engineer can prepare and analyze data, estimate model parameters, perform desktop calculations, and thoroughly document all work. This paper presents ways to use spreadsheets to perform a variety of tasks related to solving water resources problems. Applications include database management, simple computer mapping, spatial data analysis, a hydrologic budget, trend analysis, a runoff simulation, a flood routing simulation, and a continuous surface‐groundwater model. Examples from a recently completed water resources study are included.

The probability distribution of storage in the Highland Lakes reservoir system on the Lower Colorado River in Central Texas is projected up to six years into the future. Projections are based on simulation using historical hydrologic data, initial storage conditions, expected water demands, and system operation policy. Results are compared with those obtained by application of Gould's probability matrix method, which assumes annually uncorrelated hydrologic data. Although serial correlation of combined annual inflows is not statistically significant, it is demonstrated that persistence in the annual data reduces the expected system storage under steady‐state conditions from 86.5% to 81.7% of the active storage capacity. Mechanisms are illustrated for evaluating the effect of reductions in contracted water supply on future reservoir storage levels.

A computational method is described for finding the approximate optimal capacity expansion plan for a surface‐water supply system. The algorithm determines the estimated least‐costly sizing, sequencing, and operation of surface‐water storage and conveyance facilities over a specified set of staging periods. The expansion problem is separated into capital investment and system operation subproblems. A dynamic programming (DP) algorithm computes the least‐costly capital investment plan, where the optimal operating costs are approximated for each feasible set of projects. Development plans at each stage are then analyzed using a coupled set of network optimization models to compute actual system operating costs. These optimal operating costs are used to update the estimated minimum system costs. When an expansion plan is obtained by DP, which has the true operating costs, then the estimated minimum‐cost policy has been found. This approximate optimal plan is the true optimum if evaporation differences between reservoirs are insignificant. The algorithm is applied to the Guadalupe and San Antonio river basins in Texas to demonstrate its use in regional planning.

A linear programming method is suggested for evaluating and scheduling water conservation measures for deferring or avoiding a single anticipated capacity expansion project. The method is contrasted with long‐run marginal cost techniques and demonstrated for the case of a small city contemplating conservation to defer a water treatment plant expansion alternative.

Hydraulic structures are designed with reference to some natural events that could be imposed on the structure during its anticipated service life. Due to the existence of various uncertainties, the design of hydraulic structures should include as many of these uncertainties as possible. This paper closely examines the effect of inherent hydrologic and parameter uncertainties, as well as hydraulic uncertainty on the optimal risk‐based design of hydraulic structures through an example of levee system design.