摘要:

This paper presents a minimum cost method to time and size water system component expansion to meet an exogenously determined growth rate. The method analyzes the economic impact both of the economies of scale in construction and of the real cost of capital. The result is a capacity expansion model which determines when and how much excess capacity should be installed to meet increasing demands. The economic effects of timing and sizing decisions on total costs are plotted for various interest rates and levels of economies of scale. The paper demonstrates that the costs of expansion are sensitive to the increase in demand specific to the facility being planned and that the design capacity must be set individually for each separable water system component according to its particular cost function. These findings suggest that the standard practice of designing excess capacity in a water system to meet a fixed future demand (i.e., 25‐year system) should be revise

ISSN:0043-1397    

DOI:10.1029/WR005i005p00929

年代:1969

数据来源: WILEY

摘要:

Benefits due to a flood warning system are estimated by using individual structure stage damage curves for several warning periods. Typical stage damage warning time data for residences, a grocery Supermarket, and a railroad switchyard serve as examples for benefit evaluation. The application of these concepts to 650 residences involved in the 1959 flood at Meadville, Pennsylvania, indicated that reducible damages represent approximately one third of the total residential damage. Both evacuation and temporary floodproofing, two non‐structural alternatives used frequently, may be evaluated more explicitly by this metho

ISSN:0043-1397    

DOI:10.1029/WR005i005p00937

年代:1969

数据来源: WILEY

摘要:

The three purposes of this paper are: (1) to describe the major schools of thought regarding the meaning and calculation of the appropriate social discount rate, (2) to specify and defend a preferred opportunity cost approach, and (3) to present an empiric estimate of the appropriate discount rate under conditions prevailing in 1966. This rate was found to be 7.3% for 1966.

ISSN:0043-1397    

DOI:10.1029/WR005i005p00947

年代:1969

数据来源: WILEY

摘要:

Three recording rain gages in a 9.7‐square‐mile basin in southern California were used with a deterministic rainfall‐runoff model to simulate flood hydrographs and peaks and to assess the effects of data errors on simulation results. Bias in the estimation of effective basin rainfall seemed to result in curve fitting parameter adjustments which compensated for the bias. The combined effects for a storm of both difference in the time distribution of rainfall at different points and spatial variability of rainfall volume over the basin limit the possible accuracy of simulation results. The use of a single rain gage on a basin with this hydrology can at best be expected to predict peak discharge with a standard error of estimate on the order o

ISSN:0043-1397    

DOI:10.1029/WR005i005p00958

年代:1969

数据来源: WILEY

摘要:

The rescaled rangeR(t, s)/S(t, s)is shown by extensive computer simulation to be a very robust statistic for testing the presence of noncyclic long run statistical dependence in records and, in cases where such dependence is present, for estimating its intensity. The processes examined in this paper extend to extraordinarily non‐Gaussian processes with huge skewness and/or kurtosis (that is, third and/or fourth moments

ISSN:0043-1397    

DOI:10.1029/WR005i005p00967

年代:1969

数据来源: WILEY

摘要:

The movement of a rainstorm determines the spatial and temporal distributions of the rainfall over a watershed and hence affects the characteristics of the flow on the watershed. In this study the importance of the movement of rainstorms on the time distribution of the surface runoff from watersheds is demonstrated through the use of a laboratory watershed experimentation system. Experiments were performed on the impervious square watershed for 2 rainfall intensities, 4 surface slopes, and 14 rainstorm velocities. Analysis of the mechanics of water flowing on watersheds is attempted to explain the influence of movement of rainstorms on the characteristics of surface runoff hydrographs.

ISSN:0043-1397    

DOI:10.1029/WR005i005p00989

年代:1969

数据来源: WILEY

摘要:

The U. S. ESSA Weather Bureau Hydrologic Research and Development laboratory has developed a complete hydrologie model utilizing an antecedent precipitation index (API) type rainfall‐runoff relation to compute surface runoff. With increasing demand for continuous river forecasts as well as flood forecasts, it is necessary to have a model that will predict all components of flow as functions of observable independent parameters on a continuous basis. To formulate the model, existing and proved techniques were used where possible and new techniques developed as necessary. The model consists of four basic parts: a relation for computing ground‐water recession, a method of computing the ground‐water flow hydrograph as a function of the direct runoff hydrograph, anAPI‐type rainfall‐runoff relation, and a unit hydrograph. The rainfall‐runoff relation is of the incremental type, yielding a runoff computation for each 6‐hour period rather than computing the total storm runoff. This has been accomplished through the inclusion of a new parameter, retention index. Two important features of the model are the ease of adjusting parameters to observed flow and the sequential development of the four basic parts with a minimum o

ISSN:0043-1397    

DOI:10.1029/WR005i005p01007

年代:1969

数据来源: WILEY

摘要:

If ground‐water levels of a confined aquifer fluctuate with sea tides, individual values of hydraulic conductivity and specific storage can then be determined. Apparent tidal efficiency and time lag are first calculated from the water level data recorded at an observational device situated inland from the sea, taking into account the response characteristics of the observational device according to criteria established byHvorslev[1951]. The true tidal efficiency of the aquifer at the seacoast is then determined from the apparent tidal efficiency and used to obtain the specific storage. This and the tidal time lag are utilized to calculate the hydraulic conductivity. The method was tested in Prince Edward Island, Canada, and yielded results compatible with pump test data. This is a simple and inexpensive way to test a confined aquifer in the coastal environmen

ISSN:0043-1397    

DOI:10.1029/WR005i005p01023

年代:1969

数据来源: WILEY

摘要:

Artificial cuts, such as open channels and highway cuts, produce an imbalance in the original ground‐water system. The developed drawdowns due to these cuts under the condition of saturated steady flow are studied theoretically by analyzing the seepage through trapezoidal sections of earth entailing the complexity of the free surface. The procedure is then extended to actual cases of extensive aquifers where such cuts exist. The proposed method is compared with some of the available rigorous mathematical solutions, such as those given by Falkovich, Mikhailov, Meletchenko, Pavlovsky, and Polubarinova‐Kochina. The proposed method is simpler in its application and also gives a complete solution for the free surface, the discharge face, the rate of flow, and the hydropotential distribution within the affected region, whereas the rigorous methods are planned essentially for the solution of the free surface o

ISSN:0043-1397    

DOI:10.1029/WR005i005p01032

年代:1969

数据来源: WILEY

摘要:

The Robert S. Kerr Water Research Center, U.S. Department of the Interior, and Southwestern Great Plains Research Center, U.S. Department of Agriculture, recently cooperated in a field investigation of the fate of DDT and nitrates when artificially recharged into the Ogallala aquifer. The USDA provided recharge and observation wells and hydraulic equipment for injecting 350 gallons per minute of water with known concentrations of radio‐active tracer, DDT, and nitrates. Following 10 days of recharge, the recharge well was pumped for 12 days at 500 gallons per minute. During recharge the nitrates moved to the observation wells e:ssentially at the same rate as the recharge water, and the DDT was adsorbed to the aquifer material very near the recharge well. During the pumping phase, 94% of both the recharge water and the nitrates was recovered. The concentration of DDT in the pumped water was about 16 times the recharge concentration at initiation of pumping but dropped below recharge concentration within one hour. Apparently a major portion of the DDT introduced during recharge was not recovered during pumping but remained in the aquifie

ISSN:0043-1397    

DOI:10.1029/WR005i005p01041

年代:1969

数据来源: WILEY