PRELIMINARY STUDIES IN THE TERRESTRIAL DISPOSITION OF SILVER FROM CLOUD SEEDING1

ABSTRACT. Silver iodide is currently the most favored cloud seeding material in weather modification projects. While the literature indicates that its ecological effects are likely to be insignificant, its disposition in the terrestrial ecosystem after snow melt has not been adequately studied. Silver levels in soil, plant and litter material are being monitored twice a year on a mountainous area in southwestern Colorado, to determine whether annual accretion from cloud seeding can be measured with current techniques and whether significant changes in silver concentration take place in grass, aspen, and spruce communities. One AgI generator site is also being monitored. Comparison of silver concentrations in terrestrial components of the target area indicates no measurable increase after the first winter's seeding. On an ash basis, spruce foliage and litter contain about four times as much silver as soil. On a dry weight basis, soil from all three plant communities contains about six times as much silver as foliage. Consistent increases in silver concentration were found in soil and pine foliage within 200 meters of one generator site.     

ON THE EVALUATION OF OPERATIONAL CLOUD SEEDING PROJECTS1

ABSTRACT Operational cloud seeding projects, those designed to produce a desired change in the weather and that are nonexperimental in nature, continue to be pursued widely in the United States. A recurring question by scientists, project sponsors, and cloud seeders has been, “was the weather altered and if so, by how much?” Evaluation of such projects is now recognized as having scientific benefits, and a four-year study has addressed various techniques and statistical methods to perform evaluations and to learn more about how to modify the weather. Most such evaluations hinge on some type of space-time comparisons, but valid comparisons can be obtained only avoiding biases in the project design and operation. Through simulated changes in weather conditions, it was determined that the principal component regression techniques were used to evaluate selected rain and hail modification projects, revealing modification in certain projects and none in others. Various relevant issues have been examined such as use of other weather variables (covariates) to increase detection power, the validity of using historical data as controls for discrete operational periods, possible randomization options during cloud seeding operations, and analyses of individual rain events versus that based on monthly or seasonal units.     

EFFECTS OF SIMULATED CLOUD SEEDING ON STREAMFLOW OF SELECTED WATERSHEDS IN PENNSYLVANIA1

A mathematical model was developed to simulate the hydrologic behavior of five small watersheds in central Pennsylvania. Continuous hydrographs for the 6-month period, April to September 1964, were simulated. Synthesized rainfall cycles consisting of increasing rainfall by 10, 20, and 30 percent to simulate the effects of cloud seeding were processed through the watershed model to determine the effects on low flow augmentation. Other rainfall cycles used consisted of increasing every third storm by 30 percent and of developing a rainfall cycle by processing daily radiosonde data through a mathematical cumulus cloud model to obtain a prediction of rainfall following seeding. A comparison of actual and predicted hydrographs indicated that simulated cloud seeding resulted in significant monthly and seasonal water yields. In general, the results of the study appear to indicate that on a theoretical basis cloud seeding would be a feasible method of augmenting low stream-flow during the summer months on watersheds in the northern Appalachian region.     

EFFICIENT MANAGEMENT POLICIES FOR URBAN WATER SUPPLY1

ABSTRACT .This paper attempts to spell out the difficult conditions faced by urban water supply managers in achieving overall efficiency. Based upon these conditions, and changes that are likely in the next decade, it then tries to suggest strategies that would lead to even higher levels of efficiency in the future. A blending of political and economic concepts is used to make what is hoped to be a realistic analysis. What do we mean by “efficient”? The usual welfare economics definition is attainable only under a very special and highly unrealistic set of institutional arrangements. As soon as we delegate responsibility to a specialized agency we provide the opportunity, indeed we make it imperative that, in a social sense, a sub-optimization will take place. From the specifics of the indictment of this sub-optimization we can learn something about the opportunities for more efficient management in the future. In general there is an under-exploitation of multiple-function, multiple-objective opportunities. The pressures for sub-optimization hinge very directly on the sources of support and opposition to the water supply agency. A change requires the creation of a broader political base. The search for regional solutions is largely a political problem, and probably the development of flexible, responsive regional agency, so long sought, is still the answer.     

CONSERVATIONAL WATER PRICING FOR INCREASED WATER SUPPLY BENEFITS1

ABSTRACT: A study was undertaken to see if benefits from water supply could be increased by utilizing price-usage information in reservoir design studies. Three pricing policies were examined. The first policy assumed no price-use relationship, and quantity demanded was based on existing community usage with a low water rate. The price of water was set to recover system costs. A price-use relationship was assumed in the second policy and the water rate was constant. The price of water was determined from the associated system which provided maximum expected net benefits. The third policy assumed the price-use relationship and the price charged for water during each billing period was a non-linear function of storage which increased as the amount of water in storage at the beginning of the period decreased. It was found that the use of the conservation pricing policies substantially reduced storage requirements while providing demonstrable net benefits to the community and a large average supply. The conservation pricing policies substantially lowered the average price paid for water. The effect of uncertainty in consumer response to changes in price was studied by using a probabilistic price-use relationship. This uncertainty did not significantly reduce the effectiveness of the conservation policy. It was concluded that demand management by the use of a proper pricing policy could significantly increase net water supply benefits to a community.     

CONJUNCTIVE USE OF SEA AND FRESH WATER RESOURCES: AN INTEGER PROGRAMMING APPROACH1

ABSTRACT Mathematical models are formulated for selection of water resources projects to meet the future additional water requirements of a given region at the minimum present worth cost. The projects available are surface water reservoirs and desalination plants. The modles are used for selecting both the development sequence of projects and their optimum sizes. Decisions with regard to planning time horizon and discount rates are made outside of the mathematical model. The algorithm used for solving these models is an integer programming routine using the implicit enumeration technique. Some computational results are presented for a hypothetical case.     

ON PRECIPITATION SENSOR NETWORK DENSITIES FOR EVALUATING WINTERTIME OROGRAPHIC CLOUD SEEDING EXPERIMENTS1

Principal component analysis is used to investigate density requirements of wintertime orographic cloud seeding experiment precipitation sensor networks. Three passes in the vicinity of Climax, Colorado are studied. The eighteen or more evenly spaced precipitation sensors of each pass are almost completely described by three principal components. These three principal components appear to represent (i) mean precipitation, (ii) slope orientation to storm systems, and (iii) elevation. Evaluation of these principal components is implemented with two distribution-free tests, a proportionality test and the runs test. The results of this study suggest that the loss of experimental information caused by low density precipitation sensor networks may be of little consequence.     

IMPACT OF DROUGHT ON QUALITY IN A NEW JERSEY WATER SUPPLY SYSTEM1

ABSTRACT. New Jersey, together with other states in the northeast, was stricken with drought during 1961-66. The effect of this drought was most severe in the northern part of the State. The water quality of the Passaic River, which drains the urban, industrialized northeast, perhaps deteriorated the most among the major drainage systems. This river system is used as a raw-water source by 10 water suppliers. The impact of the drought upon the water supply of the Passaic Valley Water Commission, the most downstream of the basin's suppliers, which supplies an average of about 90 million gallons a day to more than 650,000 persons, is evaluated herein. The drought's impact on the raw-water quality is appraised by the comparison of before-and-after qualities of dissolved solids, dissolved oxygen, biochemical-oxygen demand, turbidity, and hardness. For example, at the worst point during the drought, monthly average dissolved-solids content in the raw water were about 210 percent, hardness, about 167 percent, and biochemical-oxygen demand about 270 percent higher than antecedent values. In general, the study concludes that the drought produced a deterioration in both raw and finished water quality, and is estimated to have increased chemical-treatment costs during the drought by about $650,000.     

WATER SUPPLY FORECASTING IN REAL-TIME1

ABSTRACT: A strategy is developed for making seasonal water supply forecasts in real time. It links the traditional regression based forecasting techniques to real-time data acquired by systems such as the Soil Conservation Service SNOTEL and the U.S. Bureau of Reclamation Hydromet networks. The concept is based on interpolating between the forecast values obtained by using real-time data in the forecast equations that bracket the real time. Different interpolation procedures were examined and the procedure for calculating confidence intervals about the forecast estimates is developed. The entire conceptual procedure is demonstrated using data from the Reynolds Creek, Idaho, experimental watershed maintained by the USDA-ARS Northwest Watershed Research Center in Boise, Idaho.     

EVALUATION OF PRACTICES IN WATER SUPPLY FORECASTING1

ABSTRACT: Snowmelt runoff is a primary source of water supply in much of the Western United States. Multipurpose planning requires long-range forecasts and the accuracy of the forecasts has a significant effect on economic benefits. In an effort to increase the accuracy of snowrnelt runoff forecasts, selected practices in water supply forecasting were evaluated. These practices include 1) using multiple regression in developing forecasting models;2) using a model that was calibrated to make forecasts an April 1 for making forecasts at other times;3) using maximum snow water equivalent measurements in forecast equations; and 4) using weighted snow water equivalent measurements for making forecasts. The results of a case study indicate that forecasting accuracy is significantly affected by these practices. Goodness-of-fit statistics may not be indicative of the accuracy of forecasts when the prediction equations are used to make forecasts for dates other than that used in calibration. The use of maximum snow water equivalentmeasurements and weighted averages did not improve forecast accuracy.     

OPTIMIZATION IN MUNICIPAL WATER SUPPLY SYSTEM DESIGN1

ABSTRACT. The design of a municipal water supply system may involve utilizing singly or in combination a conventional water supply, a desalted water supply, and a supply from a recharged aquifer reservoir. Optimization of the design requires a model formulated in a way that modern methods of systems analysis can be used. This study concerns the formulation, solution, and evaluation of a mathematical model of a municipal water supply system that includes a supply from a variable quality output desalting plant. The combined system is operated in conjunction with an artificially recharged aquifer reservoir. Also considered are short periods of water shortages. The model is set up in an approximate linear programming format, and the optimum solution (minimum cost) is found. The model is tested by applying it to the design of a supply system to meet the 1985 estimated water demand of the city of Lincoln, Nebraska. Results of this test indicate that the artificial reservoir and the existing conventional supply system are capable of supplying that demand during all but the peak period. An electrodialysis desalting system is used in this analysis. It is competitive only when the length of transmission pipeline for a conventional supply system approaches 90 miles. The model is formulated in a general way so that it can be applied to almost all situations encountered in municipal water supply design, as well as to the specific system designated for this study.     

CONSERVATION PRACTICES AND ATTITUDES AMONG MARYLAND WATER SUPPLY MANAGERS1

ABSTRACT: In addition to offsetting water supply shortages, water conservation is recognized as serving many purposes, ranging from reduced energy consumption to lower capital costs. Since the discussion of these benefits has been a recent development and has generally excluded local water supply managers, a question arises as to whether supply managers are implementing conservation programs to exploit these benefits. A survey of the managers at 35 Maryland water utilities provides insight into the prevailing attitude toward conservation in a water rich eastern state. The results indicate that most managers continue to view conservation only as a short term response to temporary supply shortages. Only 12 Maryland utilities have undertaken any form of water conservation activity and just two systems have ongoing, comprehensive conservation programs. Institutional, perceptual, economic, political, and time constraints all contribute to the managers’attitudes and general inaction. If water conservation is to be widely practiced, these issues must be addressed and the benefits attributed to conservation must be better documented and articulated to supply managers.     

SOCIOLOGICAL ASPECTS OF WATER DEVELOPMENT1

Decisions to develop water resources systems so far have been primarily taken on the basis of engineering and economic feasibilities. Very rarely, if ever, sociological feasibility has been considered, except in a very broad sense. Planning is for the people, and it should improve the quality of life. Hence, it is argued that water resources decisions ought to be primarily social ones, and that the success or failure of any resource development should not only be judged by its techno-economic excellence but also by its impact on people. Water resources planning process is discussed, and the difficulties associated with the evaluation of sociological feasibility of projects are enumerated. The social consequences of water development projects are traced through planning, construction, operation and management impacts. Finally, it is suggested that the foremost factor in the success of any water management program is the public understanding and acceptance of that program.     

A LINEAR ANALYSIS OF AN URBAN WATER SUPPLY SYSTEM1

The use of linear programming as a planning tool for determining the optimal long-range development of an urban water supply system was explored. A stochastic trace of water demand was synthesized and used as an input to the model. This permitted evaluating the feasibility of imposing demand restrictions as an effective cost reduction mechanism. The City of Lincoln, Nebraska, was used as the urban model. The fundamental problem was to allocate limited water supplies from several sources to an urban load center to minimize costs and comply with system constraints. The study period covered twenty years, and findings indicate the planning direction for stage development during this period. Sensitivity analyses were performed on cost coefficients and demands. Thirteen sources were included in the initial computations. Conclusions were that linear programming and generated demand traces are useful tools for both short- and long-term urban water supply planning. Lowering peak demands results in long-range development of fewer sources of supply and more economic and efficient use of the supplies developed.     

SYSTEMS ENGINEERING AND WATER RESOURCES IN SOUTHERN NEVADA1

ABSTRACT The Las Vegas Valley in southern Nevada has provided ample opportunity for mission oriented water resources research, and, to some extent, application of those research results. Past studies of the ground-water systems have resulted in the construction of a direct electrical analog, two digital simulation models, a Hele-Shaw fluid analog, a linear programming model, and two dynamic programming models. The work accomplished has dealt with the problems of groundwater management, waste water reclamation and artificial recharge, and conjunctive use water management. The current study is attempting to integrate previous results and new work into a detailed and realistic conjunctive use water resource management model to achieve system efficiency under more than one criteria. The research team is interdisciplinary in nature and encompasses the physical and social sciences.     

ECONOMIES ASSOCIATED WITH SIZE OF WATER UTILITIES AND COMMUNITIES SERVED IN NEW HAMPSHIRE AND NEW ENGLAND1

ABSTRACT. This study investigates economies associated with size of New England water utilities. Regression analysis techniques were applied to annual water cost and production data reported in the American Directory of Water Utilities (1968-1969). Modest economies of size in the production of water were found. Because in large communities more water is used per person, total cost increases at a slightly faster rate than population increases, but per unit costs of producing water decline. Substantial economies occurred when the number of customers was held constant and volume of water per customer increased. This study indicates possible economies when two or more of the many very small utilities combine activities to form a larger unit and by encouraging present customers to use more water.     

WATER RESOURCES AS SOCIAL PROBLEMS1

ABSTRACT. Evidence from 1969 studies in Virginia and Ohio suggests that neither community leaders nor the general public are likely to define water related problems as major problem areas. An examination of the components of a social problem tends to indicate that water problems have not moved beyond a level of minimal public concern. When respondents were willing to describe existing or potential water problems, perceptions as well as possible solutions were described in abstract rather than action-oriented terms. It is suggested that efforts to eliminate water resource problems are not likely to be effective until public concern moves to motivational and behavioral levels.     

PRECIPITATION AUGMENTATION-PROBLEMS AND PROGRESS1

ABSTRACT: Advances in the science of weather modification have provided an opportunity for significant progress in the area of precipitation management. Coordination of efforts and intensification of both laboratory and field research could lead to major advances within the decade. In view of the important decision-making role played by society, however, it is necessary that our scientific efforts be coordinated with a public relations program designed to inform and educate the public on the role and potential of artificial precipitation augmentation. In addition, careful consideration must be given to those social and legal issues related to weather modification. Environmental impact, land use, economic potential and damage liability are aU factors of importance in any comprehensive analysis. Rational solutions to questions in each of these areas is dependent upon the establishment of a sound scientific basis for operational weather modification, which should be the first priority.     

WATER RESOURCES APPLICATIONS OF STREAM CHANNEL CHARACTERISTICS ON SMALL FORESTED BASINS1

ABSTRACT. Stream channel characteristics were found to be useful indices to the hydrology of 27 small forested basins in the Northeast United States. Channel width alone explained 37 percent of the variation in mean annual runoff, whereas channel width combined with basin area explained 78 percent of the variation in mean annual runoff. This approached the percentage of variation in mean annual runoff explained by mean annual precipitation (83 percent). A simulated 15% increase in precipitation, such as might occur in a weather modification project, produced increases in channel width, depth, and channel area of 3, 4, and 8 percent, respectively.     

THE IMPACT OF PRESSURE SEWERS ON THE NATION'S WATER RESOURCES1

ABSTRACT. Over the last few years, several studies sponsored by both government and interested national engineering associations have evaluated the relative merits of pressure sewer systems. Surprisingly little data has been forthcoming, however, with regard to the effects of pressure sewers on both the economics of land development and the country's water resources. The intention of our paper is to detail the salutary effects of pressure sewers on water supply resources, the indirect effect on other resources by decreasing the contribution of sanitary sewage to their pollution, and to illustrate where, in some locations of the country, pressure sewers would benefit the economics of land development. As engineers from a large industrial firm that has built hardware that will allow the concepts stated above to become realities, we will present data to enforce our convictions. Some effects on municipal treatment plants, and emplacement costs of the system are described. Since the main thrust of our paper is to treat the effect of pressure sanitary sewers on the water resources of the country, specific peripheral data is not presented at length. The pressure sewer effects on lowering water usage in homes and the decrease in groundwater contamination by replacing septic tanks with pressure sewers in selected locations is presented. Advanced technology concepts such as energy assisted sewer systems should be considered as a favorable economic manner in which to preserve selected water resources. During the 1965 drought that affected the Northeastern section of the U.S., a federal government document reported that there was really no shortage of water, but that present water resources lacked management. Pressure sewers may be a water resources management tool and an effective one if not promulgated as a cure-all for the water pollution problems facing this nation.