Journal of Water Resources Planning and Management

Competition for water among governmental entities with common river systems has become increasingly fierce. This competition will no doubt become even more fierce as populations continue to grow and become increasingly dispersed. One of the major issues involved in water resource availability is the construction of reservoirs to provide continuous and dependable water supply. Historically, the approach to reservoir “sizing” is based on comparing the lowest historical stream flow against the highest water demands anticipated. More recently stochastic techniques have been used to estimate water yield. This paper uses a technique, “deficit analysis,” that matches available flow versus actual and/or projected demands. If demand exceeds available flow, a deficit occurs that must be satisfied by flow augmentation or reservoir capacity. Standard techniques such as the Ripple procedure or routing techniques can reveal total amounts of water required. By studying the shape and timing of deficits important additional design information can be gained. The technique is applied in a case study context to reservoir selection in the Washington D.C. Metropolitan Area.

Land application of municipal effluents is encouraged by existing federal water quality legislation and regulations as an alternative to conventional surface water discharge of partially treated effluent. However, conversion to the land application approach may impact downstream water users since the associated operations are likely to increase water consumption or change the location of return flows, or both. The legal status of such changes must be evaluated by application of state water law. In the western United States, the doctrine of prior appropriation protects appropriators whose water rights depend on return flows of prior appropriators by restricting changes in the manner in which the prior rights are exercised. In the East, the riparian doctrine sets limits on the amount of water consumption and place of water use. Although there is little direct precedent interpreting the principles of the two doctrines in relation to land application, potential constraints exist. This paper evaluates the significance of these constraints and the possible impact of water law on the adoption of the land application technique.

The operation of reservoirs often requires frequent updating of the results of the operation model. This is mainly because of errors involved in forecasting the natural inflows to the reservoirs or demands for water and energy or both. Current models used for operation usually require the use of large computers because of their core‐storage and computation‐time requirements. Frequent use of such models for the purpose of updating will often result in high computation cost and usually involves long turnaround times. This paper presents an efficient algorithm for the monthly operation of a system of two parallel multipurpose reservoirs that is solved with a minicomputer. The operation model is applied to Shasta and Folsom reservoirs of the California Central Valley Project, and the results are reviewed.

A regionalization technique is employed to obtain estimates of water availability at ungaged potential small hydropower sites in the Philippines. The flow duration characteristics at representative locations across the country were first parameterized to permit numerical interpolation. Then the geographic variation of one of the parameters was mapped to span the whole archipelago. Using regression, another parameter was expressed as a function of the drainage area. The regionalized map and the regression equation may then be used to synthesize a flow duration curve at an ungaged site. Future modifications of the procedure are suggested as additional data become available.

In many cases, channel modifications have extremely adverse impacts on aquatic communities. Rudimentary design guidelines are presented for simple structures (sills, current deflectors, and individual boulders) used to accelerate biological recovery of modified stream channels. These structures increase the physical habitat diversity of a modified channel. Data from nine case studies are presented in tabular form, including stream channel characteristics, structure dimensions, and an analysis of biological effectiveness and structural durability. Available literature on habitat structures focuses on applications to unenlarged coldwater streams with coarse bed material. Documented experience with enlarged warmwater streams that have poorly armored channels is extremely limited.

Water conservation and reuse concepts which have been used at several major power plants (200 MW or larger) in the southwest, southeast, west, and mid‐west United States are described. These plants typically employ wet‐type cooling towers and most use wet‐type, closed‐loop sulfur dioxide absorbers. All plants have limited discharge or zero liquid discharge site requirements. Basic concepts include the on‐site storage of raw water and wastewater for operating flexibility, the treatment of raw water to optimize water use, water conservation in mechanical systems to minimize blowdown or waste streams, direct wastewater reuse and indirect reuse with wastewater treatment to reduce raw water requirements and site discharges, and water management to control the overall plant water balance.

In calibrating a water distribution system model, the model user usually adjusts pipe roughness (e.g., Hazen‐Williams C factor) or water use so that pressures and flows predicted by the model agree with values observed in the field. This paper presents formulas to assist the user in deciding whether to adjust C or water use and by how much. The key to using the formulas is to observe pressures in the system for at least two significantly different use rates. Such data are often collected during fire flow tests. A model is considered calibrated to the extent that it can predict the behavior of the water distribution system over a wide range of operating conditions and water use.