摘要:

Transferable discharge permit (TDP) programs for managing multiple pollutants may be complicated by interdependent treatment costs. Under such systems pollutants may be managed as several individual commodities or grouped together and managed as a single commodity. This paper presents an approach for evaluating the cost efficiency of TDP programs in which permits for several pollutants are traded as individual commodities. Two market scenarios, representing simultaneous and sequential TDP markets, are developed to provide high and low benchmarks for cost efficiency, respectively. The scenarios demonstrate the control of biochemical oxygen demand (BOD), phosphorus, and nitrogen discharges in a typical river basin. A method for estimating feasible transfer payments under the market scenarios is also described and demonstrated for markets for BOD and phosphorus permits. The costs of these scenarios are compared with each other and with that of a uniform treatment approach. These comparisons suggest that a TDP program that manages several pollutants on an individual basis is a cost effective management strategy for conventional municipal pollutants and that any interdependencies that exist among these pollutants in terms of waste treatment costs do not limit the effectiveness of this simple program.

ISSN:0043-1397    

DOI:10.1029/WR024i007p00897

年代:1988

数据来源: WILEY

摘要:

Determining the optimal long‐term operating policy of a multireservoir power system requires solution of a stochastic nonlinear programing problem. For small systems the solution can be found by dynamic programing, but for large systems, no direct solution method exists yet, so that one must resort to mathematical manipulations to solve the problem. This paper presents a very efficient procedure for the case where high correlation exists between the reservoirs' trajectories and hence between the state variables. The procedure consists of performing principal component analysis (PCA) on the trajectories to find a reduced model of the system. The reduced model is then substituted into the operating problem, and the resulting problem is solved by stochastic dynamic programing. The reservoir trajectories on which the PCA is performed can be obtained by solving the operating problem deterministically for a large number of equally likely flow sequences. The results of applying the manipulation to Quebec's La Grande river, which has five reservoirs, are reporte

ISSN:0043-1397    

DOI:10.1029/WR024i007p00907

年代:1988

数据来源: WILEY

摘要:

The problem of diffusion and dispersion in porous media is considered in the absence of either adsorption or chemical reaction. For this situation, local volume averaging has been used to obtain both a convection‐dispersion equation and a method of closure that provides for a direct theoretical prediction of the dispersion tensor. This approach is associated with three length scales,lβ, the pore diameter,ro, the radius of the averaging volume, andLthe macroscopic length scale, and makes use of a representative unit cell to determine the dispersion tensor. Previous work suggests that extremely complex unit cells must be used to capture the observed dispersion phenomena, and complex unit cells naturally introduce another length scale, i.e., the length scale associated with the local heterogeneities. To deal with this problem, we propose the use of large‐scale averaging to account for the influence of the local heterogeneities. This leads to a large‐scale convection‐dispersion equation that contains additional terms involving time derivatives which arise as a result of the presence of heterogeneities and which do not appear in the conventional local volume average convection‐dispersion equation. The first new term contains the second derivative with respect to time and is likely to be unimportant for time scales appropriate for groundwater transport processes; however, it may be important for small‐scale laboratory experiments. The second new term contains a mixed space‐time derivative which may be important for many cases of practical interest. A closure scheme is presented that allows for the theoretical determination of all the coefficients that appear in the large‐scale convective‐convection

ISSN:0043-1397    

DOI:10.1029/WR024i007p00913

年代:1988

数据来源: WILEY

摘要:

The closure scheme which is presented in part 1 (Plumb and Whitaker, this issue) is solved for a stratified system and for a two‐dimensional spatially periodic system. By this we mean that the ω and η regions, which make up the heterogeneous media, are distributed in a spatially periodic manner. The solution to the closure problem yields the information necessary to determine the large‐scale dispersion tensor and the other coefficients that appear in the large‐scale dispersion equation. The theoretical results for the stratified system exhibit an increase in the longitudinal dispersion coefficient of several orders of magnitude over that which would be predicted using established correlations based on laboratory experiments with seemingly homogeneous porous media. For the cases studied, the coefficient of the mixed space‐time derivative appears to be significant and this coefficient increases for those conditions which yield increasing longitudinal dispersion coefficients. The results for the two‐dimensional spatially periodic system are in qualitative agreement with experimental observations, and we found that both the size of the heterogeneity and the difference in the hydraulic conductivity between the two regions had an important influence on the large‐scale dispersion tensor. As in the case of a stratified medium, the predicted values of the coefficient of the mixed space‐time derivative (the skewness vector) indicate that this term could be a significant factor in the prediction of mass transport in heterogeneo

ISSN:0043-1397    

DOI:10.1029/WR024i007p00927

年代:1988

数据来源: WILEY

摘要:

The application of time domain reflectometry (TDR) to determine soil water content, using only the time axis of a TDR trace, has been widely investigated. Other interpretations from the TDR trace, such as the determination of electrical conductivity, make use of the amplitude or reflection coefficient values. These latter interpretations must take account of multiple reflections in the media. A multiple‐reflection algorithm is developed which takes account of primary reflection first, then provides for inclusion of higher‐order reflections as well. The algorithm is formulated to generate the TDR trace from a sequence of known dielectrics. The inverse case is analyzed where the dielectric constant of the layered medium is calculated from a measured TDR trace. The model allows for both conductive and nonconductive dielectrics. Experiments showed that the model is a reasonably good qualitative representation of the layered nonconductive media with a wide range of dielectric constants. There is insufficient information in a TDR trace to solve the conductive cases except for a single layer. From KCl solutions at two concentrations the experiments showed that instantaneous reflection and transmission are inadequate assumptions for conductive systems. This indicates the need for caution when applying the model to conductive media such as soils, especially where soil water content is not unif

ISSN:0043-1397    

DOI:10.1029/WR024i007p00939

年代:1988

数据来源: WILEY

摘要:

The simultaneous measurement of water content and electrical conductivity of soils and KCl solutions was achieved using time domain reflectometry (TDR). Coaxial transmission lines varying in length from 90 to 300 mm contained either KCl solutions or soil of varied water and salt content. The water content of soil or dielectric constant of the water solutions was determined from the travel time. The measured dielectric constant of KCl solutions was unchanged from that of pure water (81) at those concentrations where there was sufficient reflected signal for measurement. Two analyses were used for determination of electrical conductivity, one based on signal attenuation after one “round‐trip” and the second based on a thin sample approximation for the signal reflection and attenuation. Reference measurements of conductivity were made on the same samples using low‐frequency conductance bridge measurements. These analyses of the TDR traces showed that for water solution both the thin sample analysis and the analysis after a signal had traversed one round‐trip yielded conductivity in agreement with bridge conductivity values. This indicated that the imaginary part of the complex dielectric constant was negligible. For soils the thin sample analysis was in general agreement with the bridge measurements. From the analysis of signal after one round‐trip in soils there was indication that the imaginary part of the dielectric constant should not be assumed negligible. Further investigation of the frequency dependence of the dielectric constant and attenuation will be required to identify the relative contributions of the real and imaginary parts of the dielectric constant to measurement by TDR. The effect of impedance‐matching transformers on conductivity measurements in the field has yet to b

ISSN:0043-1397    

DOI:10.1029/WR024i007p00945

年代:1988

数据来源: WILEY

摘要:

An optimization model is presented for selecting among and sizing potential reservoirs on a river basin. The provision of water to meet municipal and industrial, irrigation, and hydropower demands, as well as recreation and flood control at each candidate reservoir site are considered. A compact, nonlinear optimization formulation for the reservoir sizing problem is derived by decomposing the problem into simulation and optimization components. Reservoir storage capacities needed are determined using a modified sequent peak algorithm to simulate monthly reservoir operation. Simulation is also employed to determine optimal sizes for hydropower generators at each site. Similarly, average annual flood control and recreation benefits are determined through simulation. An optimization scheme that considers annual yields for each purpose with specified reliabilities and conservation and flood storage as decision variables is used to integrate these simulations into an optimal screening algorithm. Significant savings in computational and memory requirements over other formulations are offered at the expense of nonlinear functional forms. Applications of the model developed with data from sites on the Lower Bear River are presented.

ISSN:0043-1397    

DOI:10.1029/WR024i007p00953

年代:1988

数据来源: WILEY

摘要:

The greatest difficulty in applying the geomorphologic instantaneous unit hydrograph is the estimation of the time scale of the hydrologic response of a basin. We derive the time scale from the effective streamflow velocity of the highest‐order stream and the spatial distribution of velocity throughout the stream network. The latter is described by a dimensionless geomorphologic function with a single‐shape parameter. The proposed method is applied to some Italian bas

ISSN:0043-1397    

DOI:10.1029/WR024i007p00969

年代:1988

数据来源: WILEY

摘要:

A comparison of six equations which estimate free water evaporation using climatological data show that the equations vary greatly in their ability to define the magnitude and variability of evaporation. The equations compared included the Kohler‐Nordenson‐Fox, Kohler‐Parmele, Linacre, Priestley‐Taylor, Stewart‐Rouse, and deBruin, which range from equations requiring only temperature data to those requiring temperature, radiation, wind, and humidity. Several years of monthly estimates for May through September were made at two locations in Wyoming using each of the six equations. Means and standard deviations of the monthly data were calculated and t‐tests and regressions comparing the data from the various equations and against pan data wer

ISSN:0043-1397    

DOI:10.1029/WR024i007p00979

年代:1988

数据来源: WILEY

摘要:

This paper presents the multidimensional representation of the cumulative rainfall process and derives a closed‐form expression for the mean and space‐time covariance functions. A parameter estimation procedure is developed. Sensitivity analysis provides useful information for devising the parameter estimation strategy. The cumulative rainfall model is applied to 8 years of digitized rain gage data from the Walnut Gulch Experimental Watershed. The most useful feature of the model is its self‐consistency, implying that even after using information from a given limited set of data it still leads to realistic parameters which reproduce historical statistics at several levels of time and space s

ISSN:0043-1397    

DOI:10.1029/WR024i007p00985

年代:1988

数据来源: WILEY