摘要:

A comparison between the fixed schedule of planned expansion of water supply sources and an alternative expansion program based on a short‐term decision from monitoring reservoir levels, water use, and streamflows and employing water reuse capacity and new source development is simulated for the Colorado Springs, Colorado, municipal water system. For this complex, fast growing system with supply based on streamflows and some current reuse capacity the alternative plan postpones major new development an average of 14 years at a cost at present value of half the original planned expansio

ISSN:0043-1397    

DOI:10.1029/WR011i005p00607

年代:1975

数据来源: WILEY

摘要:

A demand curve for land treatment of municipal waste water is derived assuming a profit‐maximizing framework. The outputs of a waste treatment facility are taken to be volume of waste water, degree of waste removal, and potentially marketable by‐product. The demand curve for land treatment technology is estimated by utilizing data collected from 125 U.S. cities. The dependent variable is adoption or non‐adoption of land treatment, and coefficients are estimated by nonlinear regression. The price of by‐products (water), required degree of treatment, price of capital, and local construction cost share all significantly increase adoption. Volume of river flow, rainfall, and volume of effluent flow all have a significant negative effect on adoption. Land prices were insignificant, a factor which is believed to be due to the nonpurchase of land by many land treatment fac

ISSN:0043-1397    

DOI:10.1029/WR011i005p00616

年代:1975

数据来源: WILEY

摘要:

The computer time required for a water resource optimization problem by dynamic programing (DP) or discrete differential dynamic programing (DDDP) may be considered as the sum of the compiling time for programing language translation, the initiating time for the program, and the execution timeTE. The execution time is the dominant component of the total computer time and may be formulated asTE=TaMN Пi=1SQiПj=1DPj, in which Tais the time for one unit operation,Mis the number of iterations involved in optimization,Nis the number of stages, and Qiand Pjare the number of feasible values that state variablei(i= 1, 2, …, S) and decision variablej(j= 1,2,…,D), respectively, can take in each iteration or in the optimizational procedure. The value ofTadepends on nature of problem, type of computer, method of coding, kind of compiler, and other factors. The computer memory required for this optimization problem may be considered as the sum of the machine memory which is relatively constant, the code memory which increases slowly with the problem size, and the data memory which increases rapidly with the problem size. The data memory consists of the basic data memory, the performance data memoryP= 2 Пi=1sQi, and the optimal decision data memoryT=NDПi=1sQi. The cost trade offs involved in replacing core memory by slow‐speed memory (disks or tapes) are investigated. The computers used in the analysis include: IBM 360/50, IBM 360/75, IBM 360/91 and Burroughs B‐6700. The problems verifying the formulas include operations of single‐and multiple‐purpose reservoir networks and optimal design of storm sewer system

ISSN:0043-1397    

DOI:10.1029/WR011i005p00621

年代:1975

数据来源: WILEY

摘要:

On the basis of Monte Carlo experiments it was noted that in the absence of information about the distribution of floods and the economic losses associated with the design of flood reduction measures, the use of the normal distribution to represent the distribution of floods is generally better than either the Gumbel, log normal, or Weibull distributions. Nothing is gained in terms of reducing expected opportunity design losses if the underlying distribution F(x) is identified over and above simply using the normal as the assumed distribution. On the other hand, without identifying F(x) but with some detailed specification of the ratio of overdesign to underdesign losses and with a limited specification of the skewness of floods, a considerable reduction in the expected opportunity design losses results.

ISSN:0043-1397    

DOI:10.1029/WR011i005p00629

年代:1975

数据来源: WILEY

摘要:

The purpose of this research is to determine the consequence of using Markovian and self‐similar synthetic data generators in the economic design of a multipurpose reservoir. This leads to the study of two engineering problems: sizing a reservoir and operating a reservoir. This work is the sequel to the paper ‘Practical Application of Fractional Brownian Motion and Noise to Synthetic Hydrology’ (Chi et al., 1973). To study the effects of synthetic data generators, a one‐reservoir model is used as a case study and typical flood, water supply, and recreation cost functions are employed to answer the questions: Does the complex model yield a more accurate economical answer? What are the trade offs between using simple or complex hydrologic models in operating and in sizing analysis? Is it worth the extra effort in analysis cost over ranges of simulation periods? The optimum reservoir size is found to agree within 15% for the two hydrology models. A higher variance for the self‐similar solution is present. Both streamflow generators give cost plus loss estimates which differ about 5% under optimal conditions. A 95% confidence band for total cost (i.e., expected present value of losses plus fixed cost of the reservoir( shows the historic result to be conservative. Computing times for the generation of synthetic streamflow differ by an order of magnitude for simple and complex models. The problem of sizing is sensitive to the different streamflow generators; regret is of the order of 5%. Operating rules of a reservoir are fairly insensitive to the choice of the streamflow model. Furthermore, one can state that given limited resources, a Markovian model can be used for both sizing and operating a multipurpose reservoir. And no discrimination between a simple Markovian model and a complex self‐similar model cou

ISSN:0043-1397    

DOI:10.1029/WR011i005p00648

年代:1975

数据来源: WILEY

摘要:

Daily discharge flows are transformed by a recession equation into a dimensionless time series which reflects the storage characteristics of a watershed and also indicates the direct response of a watershed to precipitation. Spectral techniques of time series analysis are employed as an exploratory tool for suggesting different models describing a watershed's response.

ISSN:0043-1397    

DOI:10.1029/WR011i005p00657

年代:1975

数据来源: WILEY

摘要:

Evaporation is estimated for Lake Huron by the energy budget method and compared to available mass transfer estimates. Data were from representative shoreline station measurements and vessel cruise measurements. Agreement between evaporation by the energy budget and by mass transfer was reasonable from February through July with the exception of May when measurement of the heat content was a problem. For the remainder of the year the disparity is marked. The principal difficulty encountered was the lack of meteorological measurements on the lake or adequate techniques to extrapolate the quantities from shoreline data. Quantitative monthly values for each component in the budget equation are the first published for Lake Huron and one of the few sets available for the Great Lakes.

ISSN:0043-1397    

DOI:10.1029/WR011i005p00661

年代:1975

数据来源: WILEY

摘要:

Prosper, a phenomenological model of water exchange between soil, plant, and atmosphere, was used to simulate evapotranspiration and annual drainage for 2 years from a mature oak‐hickory forest in the southern Appalachians. The simulation was tested by comparing drainage to measured streamflow. In a year of unusually high precipitation the simulated annual drainage was within 1.5% of measured streamflow. Simulations were also performed by using the same 2 years of meteorologic data, but vegetation parameters were changed to represent a young white pine plantation and a regrowing hardwood forest 1 year after clear‐cutting. The model estimated that drainage for an average rainfall year was reduced 20 cm by a 16‐year‐old white pine plantation and increased 36 cm by clear‐cutting. These results were comparable to changes of −20 and +38 cm observed in watershed experiments at Coweeta Hydrologic Laboratory. Simulated evapotranspiration during the summer was nearly identical for hardwood and pine forests, while winter and early spring water loss was greater for pine. Simulation suggests that the greater evapotranspiration by pine was due to increased interception in all seasons and increased transpiration in the dormant season. For the clear‐cut area, simulated evapotranspiration was considerably less than it was for the pine or hardwood forest and thus caused simulated soil moisture contents to be greater during the

ISSN:0043-1397    

DOI:10.1029/WR011i005p00667

年代:1975

数据来源: WILEY

摘要:

With the experience gained from an earlier gage (Tabler and Jairell, 1971), significant innovations have greatly improved the operation of a simple, inexpensive instrument for recording blowing snow. The most important improvement is the efficient turntable design which allows the precipitation gage to be independent of the snow trap, the result being a high‐quality chart record. Principal advantages include simplicity, inexpensiveness, and suitability for operation in remote areas lacking electrical power. The relationship of snow caught by this gage to snow accumulation behind a snow fence should be studied further as a means of calibration. It appears that the gage can be used to estimate total snow transport during drifting event

ISSN:0043-1397    

DOI:10.1029/WR011i005p00674

年代:1975

数据来源: WILEY

摘要:

A mathematical and statistical study which shows the flexibility and limitations of the log Pearson type 3 distribution is carried out. The results obtained indicate the various forms of density function and relationships that exist between distribution parameters and moments, coefficient of variation, and coefficient of skewness. The method of fitting proposed by the Hydrology Committee of the Water Resources Council is compared with a new method which instead of using moments of the logarithmic values retains the moments of the original data. In the case of events with a large return period the results obtained by the two methods may deviate appreciably, and because in the proposed method the same weight is given to each of the observed values, it will result in a better fit of the data.

ISSN:0043-1397    

DOI:10.1029/WR011i005p00681

年代:1975

数据来源: WILEY