Journal of Water Resources Planning and Management

Many water utilities in the United States depend upon surface water as their primary source of drinking water. Toxic screening models can be used to provide a means for identifying and assessing the pollutants likely to be in water utility source water from point and nonpoint upstream dischargers. Two case studies are presented to evaluate this concept. One is based on the stretch of Ohio River between the Kanawha River and Cincinnati, OH and ranks the vulnerability of the utilities along this stream segment to organoleptic, toxic, and carcinogenic pollutants. The second case study uses the lower Mississippi to illustrate the use of flow routing models to predict the concentration of contaminants at downstream utilities, based on upstream industrial discharges. The important interaction between time of passage and disappearance coefficient of the pollutant is illustrated.

In order to improve the reliability of hydraulic network models as well as eliminate the need for trial‐and‐error calibration methods, an explicit calibration algorithm is proposed. The calibration algorithm is formulated in terms of headloss coefficients and is developed from a reformulation of the basic network equations. The basic network equations are solved explicitly for headloss adjustments to exactly meet one or more measured conditions of pressure or flow for given network loading and operating conditions. The adjustments determined in this manner are used to revise pipe roughnesses or defined concentrated head (minor) losses to meet the measured conditions. In order to demonstrate the feasibility of the approach, the developed algorithm is applied to an example network.

An optimal control management model for spatial and temporal allocation of groundwater is presented. The management model integrates a physically‐based finite‐difference aquifer simulation model, and a linear‐quadratic optimal control model. The objective functional represents present discounted benefits determined from the derived demands for irrigation water net of pumping costs. The dynamic aquifer simulation equations are directly incorporated in the optimal control model, and the cost of pumping is calculated using a drawdown correction. Aggregated parameters obtained from detailed digital model studies such as by the US Geological Survey can be used to readily calibrate the model for a particular groundwater basin. A case study application is presented to demonstrate the potential use of the model as a management tool.

Conflicts occur between the commerce clause of the US Constitution and state statutes that forbid the export of water to other states. In Nebraska versus Sporhase, such a conflict was examined and a far‐reaching decision was made. The US Supreme Court held that, except under narrowly defined conditions, it is illegal to apply a statute to prevent the movement of water from one state to another. Water is considered to be a form of commerce similar to wheat or steel. While state planning may be applied to water (its use and supply in the state), it cannot be used to prevent someone from out of state from appropriating water for out‐of‐state uses.

Large‐scale water resburce projects must be operated and maintained so that the benefits for which they were built actually occur. The key to substantial improvement in project performance is in operating the various project components in a comprehensive, integrated fashion. Optimal integration of the system's many facets and analysis of tradeoffs between conflicting objectives requires the assistance of analytical tools to provide information on which to base management decisions. An interactive river basin network flow model called MODSIM2 has been developed for this purpose. MODSIM2 is applied to a large irrigation/hydropower system in the Philippines, while the upper Pampanga River Integrated Irrigation System (UPRIIS) is in Central Luzon. Through use of the calibrated model, it was possible to: (1) Locate a bottleneck in the conveyance system causing irrigation shortage; and (2) show that with integrated operations, firm energy generation can probably be increased up to four times the current level without causing irrigation shortage.

A statistical procedure is developed for estimating generalized skew coefficients used in the WRC Guidelines for flood frequency estimation. The method is based on weighted least squares regression in which the weights are determined by separating residual variance into that due to model error and that due to sampling error. Results indicate that actual model errors are much smaller than estimates provided by ordinary least squares regression procedures.

This paper illustrates that it is possible to calibrate accurately a mathematical model of a complicated water distribution system (271 nodes, 307 pipes, 9 pressure reducing valves) if adequate and accurate data are collected. It is essential that the model be calibrated for a range of water use rates and patterns as otherwise it is possible for the model to appear to be calibrated even though it contains significant errors. For example, in this system it was possible to make the model appear calibrated for C‐factors that varied by a factor of 3 provided that sufficient errors were made on other input parameters. The key to collecting adequate data is that the head at boundary nodes (pumps, tanks, pressure reducing valves) be known when pressure readings are made in the system.

Tucson, AZ is one of the nation's largest cities entirely dependent on groundwater for its water supplies. It faced a 1980 overdraft of over 60% of the area's total groundwater withdrawals. The quality of its diminishing supply also is threatened by various sources of contamination. But important efforts are being made to solve these water problems by municipal conservation, by Arizona's adoption of a stringent new Groundwater Management Act, and by federal settlement of Indian water claims and construction of the Central Arizona Project. The competition among water uses—agricultural, municipal, and industrial—has not been eliminated, but a framework has been established for Tucson to end its overdrafts eventually. However, some major problems have not yet been resolved, including the socioeconomic impacts of water market solutions on Tucson area farmers and Indians, and groundwater contamination (primarily from copper mine tailings and trichloroethylene, TCE). Most importantly, fundamental issues of equity and carrying capacity are raised by the actions needed to provide water for Tucson's explosive growth in the midst of a desert.

This paper provides a brief description of the most common method of calculating urban flood damages‐prevented benefits and critically appraises the data, assumptions, and techniques that may lead to erroneous estimates of benefits. Several issues were identified that, to the writer's knowledge, are not typically addressed in studies: (1) Bias resulting from inaccurate estimates of structure elevations; (2) failure to consider that unemployed labor may be used to repair flood damages; (3) failure to consider replacement of existing structures; and (4) underestimation of willingness to pay for repairs. With a better understanding of the weaknesses of current techniques, future research and data gathering can be directed to yield the greatest increase in overall accuracy.

An ensemble of analytical tools is used to identify capacity expansion alternatives for the Delaware River dredged‐material disposal system. Characteristics of the river and riparian area are stored and analyzed with a geographic information system. Site attractiveness maps produced with these data yield an array of potential expansion sites. The least‐costly schedule for acquisition of these sites is identified with branch‐and‐bound enumeration. For the enumeration, the operation cost of alternative expansion plans is evaluated with a network‐flow programming model of the disposal system.