摘要:

Statistical or Bayesian decision theory was applied to a farm management situation in Sevier County, Utah, which is characterized by risk and uncertainty with respect to the supply of late season water. Information on reservoir carry‐over and mountain snowpack becomes available just before resources must be committed. These data are incorporated into the model as predictors of the late season water supply. Use of this predictive information is compared to the ‘no data’ situation, in which the predictive information is not used, and also to the ‘perfect knowledge’ situation, in which the availability of full information at the time of resource commitment is assumed. A limited growing season and other physical constraints along with lack of markets restrict the flexibility of the management decisions so that the profitability of adapting the technique is not great in the present application. However, the technique is shown to be usable and potentially profitable in a variety of management s

ISSN:0043-1397    

DOI:10.1029/WR007i003p00443

年代:1971

数据来源: WILEY

摘要:

Water pollution is perceived by the general public to be of increasing concern as a major problem facing the state. From a survey of a representative sample of adults in Wisconsin, it was shown that the public has rather definite ideas about what constitutes a description of pollution. The respondents mentioned algae and murky, dark water but did not often mention attributes such as chemicals or disease germs that are not detected by the human sensory system. When the respondents were asked to name water in the state that they felt was polluted, they named waters that in fact have the characteristics they described when defining pollution. The most widely used indicators of water pollution seem insufficient in light of the public definition of, and concern about, water pollution.

ISSN:0043-1397    

DOI:10.1029/WR007i003p00453

年代:1971

数据来源: WILEY

摘要:

Regional water quality management models for river systems with multiple sources of pollution are reviewed. The optimal solution is analyzed from the point of view of comparing the efficacy of more intensive waste treatment by the individual waste discharger with the efficacy of increased upstream treatment. The value of upstream waste treatment to the individual discharger diminishes the further upstream one moves. A relationship for evaluating this trade off is presented. The alternative situations that might occur in a regional system are then analyzed. An application of the analysis to a hypothetical region is presented.

ISSN:0043-1397    

DOI:10.1029/WR007i003p00458

年代:1971

数据来源: WILEY

摘要:

An attempt is made to apply a previously developed general model of investment‐pricing decisions to the particular problem of choosing the timing and sizes of additions to capacity in urban water supply systems. On the basis of empirical data, typical but hypothetical cost and demand curves for water supply are defined and incorporated into the model. The model is then solved under varying assumptions with regard to rate of growth in demand, the level of the discount rate, and the length of the planning horizon. The results are compared in terms of their efficiency with results that could be expected from conventional approaches to the problem by employing certain arbitrarily assumed schemes of average cost pricing combined with rules of thumb criteria for choosing the size and timing of capacity investment.The major conclusions reached are that at present we do not have the empirical data necessary to effectively implement the general model in the water supply area and that the results do suggest that the multistage marginal cost approach toward planning and operating urban water supply systems might be 10–20% more efficient than traditional average cost approac

ISSN:0043-1397    

DOI:10.1029/WR007i003p00463

年代:1971

数据来源: WILEY

摘要:

The sequencing and scheduling aspects of some important capacity expansion problems encountered in water resources development are studied. Dynamic programing algorithms are developed for both project timing problems and combined project selection and timing problems involving durable high cost water supply projects, which in the aggregate are subject to continuous time demand requirements. The structure of the problems is successfully exploited to produce computationally efficient algorithms to solve problems of the dimension encountered in water resources systems. The computational superiority of these algorithms over conventional dynamic programing algorithms is discussed and illustrated by a numerical example.

ISSN:0043-1397    

DOI:10.1029/WR007i003p00479

年代:1971

数据来源: WILEY

摘要:

A chance constrained formulation of a multireservoir system is considered. Minimum and maximum release requirements, minimum pool level, and minimum freeboard capacity are specified by the management for each reservoir. The management also specifies the maximum probabilities beyond which these requirements are not violated. By proposing linear decision rules for the releases, the authors reduce the chance constrained formulation to an ordinary linear programing formulation. The linear decision rule states that the release from a reservoir during a given time period is defined by the difference between the ‘net initial storage’ and a ‘decision parameter’ for that reservoir during that period. The objective function considers only the total cost of reservoirs, because the primary objective is to meet the various given demands at a minimum cost. This model has been applied to the Minnesota Rive

ISSN:0043-1397    

DOI:10.1029/WR007i003p00485

年代:1971

数据来源: WILEY

摘要:

Five‐stamen tamarisk, an important phreatophyte in the southwestern United States, is difficult to eradicate for water salvage. There also is increasing opposition to its eradication because this species provides cover for wildlife and greenery in the environment. The application of nontoxic antitranspirant sprays to reduce tamarisk transpiration may be an alternative to eradication. We tested several antitranspirants, including a combination of the monomethyl and monoglyceryl esters ofn‐decenylsuccinic acid (MDSA‐GDSA), 8‐hydroxyquinoline sulfate (8‐HQS), and phenylmercuric acetate (PMA), on tamarisk in greenhouse and field environments. PMA was toxic at a concentration of 0.001Mand was therefore not considered in the evaluation described below. The effects of MDSA‐GDSA and 8‐HQS on transpiration, growth, net photosynthesis, dark respiration, relative stomatal apertures, chlorophyll and protein contents, and foliage temperature were evaluated. Transpiration rates of plants treated with MDSA‐GDSA and 8‐HQS were 25–35% less than those of control plants for 20 days in the greenhouse and for at least 5 days in the field. Growth was reduced for 2–3 weeks, and net photosynthesis for less than 1 week. The other physiological factors were not changed substantially. Foliage temperatures increased 2°–3°C for 3 days following treatment in the field. Further study for possible management

ISSN:0043-1397    

DOI:10.1029/WR007i003p00499

年代:1971

数据来源: WILEY

摘要:

The energy and water balance components of a 70‐year‐old Norway spruce forest, a 2‐year‐old alfalfa field, and a potato field near Munich, Germany, were computed for the period May–October 1965 by using hourly averages of metorologic parameters. Turbulent diffusion and energy budget methods were used to determine evapotranspiration and convective exchange. The two methods yielded satisfactory, agreement for the low crops but not for the forest. The mean seasonal albedo values for the potatoes and the alfalfa were 0.18 and 022, respectively. The albedo of the forest was obtained for 1 day and averaged 0.05. The shortwave incoming radiation over the forest was 12% less than that over the fields. The net shortwave radiation over the forest was 2 and 7% greater than that over the potatoes and the alfalfa, respectively, whereas the long wave emission from the forest was 22 and 15% less than that from the potatoes and the alfalfa, respectively. The total net radiation over the forest was 20% greater than that over the alfalfa and 16% greater than that over the potatoes. Sensible heat flux from the forest was 2.6 and 1.6 times greater than that from the alfalfa and the potatoes, respectively. Evapotranspiration from the forest was 4% less than that from the alfalfa but 14% greater than that from the potatoes. The roughness lengths of the forest and the fields were about 0.1 of their heights. The zero plane displacements were 0.71 and 0.5–0.6 of the heights of the forest and the crops, respectively. The exchange coefficient at the top of the trees was about 100 times as large as that at the tap of the crops. The water supply in the soil was not limiting on any of the three experimental sites during the vegeta

ISSN:0043-1397    

DOI:10.1029/WR007i003p00511

年代:1971

数据来源: WILEY

摘要:

Rainfall on five soil and water conservation research watersheds near Treynor, Iowa, varied from 18 to 22 inches for the period of May 28 to June 27, 1967. This unique series of events has a return period that exceeds 100 years, based on the 97‐year Weather Bureau record at nearby Omaha, Nebraska.Surface runoff from two corn cropped watersheds planted on an approximate contour approached or exceeded 50% of the storm rainfall during the period. Surface runoff was 8% or less for all rainfall events on a corn cropped, terraced watershed and 17% or less for all but one storm on a grassed watershed.These rains occurred a few weeks after planting when the corn plants were only 6 inches tall; consequently, little or no erosion protection was provided for the bare, loose soil. Sheet rill erosion rates were 75 to 100 tons per acre on the contoured corn watersheds. By contrast, conservation practices on two other watersheds limited the sheet rill erosion to 2.5 tons per acre.Gullies on the contoured corn watersheds eroded severely, whereas conservation practices on the other watersheds reduced gully erosion to an insignificant amoun

ISSN:0043-1397    

DOI:10.1029/WR007i003p00524

年代:1971

数据来源: WILEY

摘要:

An iterative process that is used to solve flow dynamics is studied; a highway culvert and embankment system serves as an example. Time step criteria governing convergence of the iterative process is analyzed. The Lipschitz ratio is applied to calculate the controlling algebraic time step relationship. The time step for convergence is shown to vary with current inflow and antecedent storage. Parameters of the iterative process are calculated for the example by assuming nonlinear functional forms for stage storage and discharge storage relationships and by inferring the appropriate coefficients. Numerical results are presented for several extreme cases that bracket orifice and weir flow conditions. The approach should be applicable to other hydrologic systems such as small dams, catch basin flow, and retarding basins. As for the route or convolute question, which concerns the direct conversion of rainfall excess to watershed outflow, this analysis aids in the selection of a time increment for direct routing.

ISSN:0043-1397    

DOI:10.1029/WR007i003p00536

年代:1971

数据来源: WILEY