摘要:

A climatic model developed for estimating the depressing effect of drought on the diameter growth of loblolly pines in the southern United States is used to project potential pine growth under conditions of no soil moisture deficit, which irrigation could assure. The regional distribution of the additional growth demonstrates that the benefits of irrigation would increase from the Atlantic coast toward east Texas. The dollar value of the additional growth based on the current price of pulpwood is compared with the costs necessary to irrigate southern pines. Under present conditions of technology, costs of irrigation would exceed benefits. Technological changes, higher pulpwood prices, or decisions of the federal government to improve southern forests may justify the irrigation costs necessary to increase southern pine production.

ISSN:0043-1397    

DOI:10.1029/WR009i006p01485

年代:1973

数据来源: WILEY

摘要:

The capacity expansion of a mixed hydrothermal power system is analyzed by means of dynamic programing to compare alternative sequences of power development and by means of a fast running, approximate simulation model to evaluate the operation of possible power system states in the dynamic programing model. Because the simulation of all states in the dynamic programing model is too time consuming, only selected states are simulated, and these states are identified by using an iterative solution procedure. The resulting ‘dynamic programing‐simulation strategy’ is applied to the preliminary planning of the expansion of a mixed hydrothermal power system in Brazil. The solution procedure is computationally efficient and leads to a substantial reduction in the estimated cost of a future sequence of power develo

ISSN:0043-1397    

DOI:10.1029/WR009i006p01497

年代:1973

数据来源: WILEY

摘要:

In the representation of natural catchment systems with mathematical models, a relatively wide range of choice exists among models of various degrees of completeness and sophistication. When the cost, as well as the appropriateness, of a model is considered for a particular purpose, it is desirable to have an objective criterion to make this selection. The concept of entropy as used in information theory provides one such criterion. Entropy is a measure of the degree of uncertainty of a particular outcome in a process; therefore, in dealing with the prediction of a hydrologie variable such as streamflow, one can compute the entropy of this variable from historical data and thus characterize the unexpectedness or variability inherent in the process. This represents a property of the system and is called marginal entropy. It is likewise possible to evaluate the uncertainty of the predictions made by a given mathematical model of the catchment by comparing these predictions with the measured flow. This is done through the conditional entropy. By combination of these two entropy functions a criterion called ‘transinformation,’ providing an objective evaluation of the goodness of the model, is obtained. The important point to note is that this assessment depends not only on the model but on the characteristics of the output series resulting from the natural process. The above criteria, which have been discussed in other contexts, were applied to a basin for which a number of years of historical flow record and concurrent model simulations were available. The results show the value of the entropy criterion in judging model performance as well as the difficulties and limitations of the met

ISSN:0043-1397    

DOI:10.1029/WR009i006p01511

年代:1973

数据来源: WILEY

摘要:

A synopsis of self‐similar stochastic processes is presented with special emphasis on fractional Brownian motion and noises. Detailed analysis and discussion are on the approach of ‘fast fractional Gaussian noises’ by Mandelbrot and his collaborators. Modifications are incorporated and parameter selection criteria suggested so that the method becomes simpler, more flexible to use, and easier to follow. A step‐by‐step procedure is included for convenience of ap

ISSN:0043-1397    

DOI:10.1029/WR009i006p01523

年代:1973

数据来源: WILEY

摘要:

Maximum likelihood equations for the estimation of Gumbel distribution parameters from censored samples are derived; expressions for their large‐sample standard errors are also given. Censored samples arising in annual maximum flood series are described, and it is shown that a set of historic floodmarks may, under certain assumptions, be combined with recent noncensored data, to form what is essentially a censored sample. Maximum likelihood methods are applied to such a sample, and the resulting estimates are compared with those obtained from the recent data alone. The estimates agree closely, and the use of the extra information contained in the historic floodmarks is shown to lead to a reduction in the large‐sample standard errors of the estima

ISSN:0043-1397    

DOI:10.1029/WR009i006p01534

年代:1973

数据来源: WILEY

摘要:

The technique of data display, the synographic mapping system (Symap), was applied in ecological studies of unstratified Gulf Coast estuaries. Thirty‐four computer maps of spatial distribution of primary nutrients and chlorophyll concentrations in San Antonio and Matagorda (Texas) estuaries were prepared from survey data covering the period 1970‐1971. The maps provided a convenient means for detecting the sources of estuarine enrichment by primary nutrients and of seasonal changes in dispersion patterns. Weighted average concentrations of each compound in the entire estuarine water mass were determined from such displays and used in comparison of concentrations for different months of the survey period. The data presented on Symap displays were used in the determination of mixing and exchange efficiency in the estuaries. The results indicated that incoming nutrients often have very short residence times. Behavior of the nutrients followed patterns similar to those discussed by Pritchard (1954). It was demonstrated, however, that the efficiency of exchange and residence time of each compound vary significantly within a year, conditioned by variable compound loading, quantity of tributary runoff, range of tidal activity, and variable biological food demand. An attempt was made to relate the chlorophyllaconcentrations obtained as weighted averages from Symap displays to concentrations of phosphorus, nitrogen, and carbon, to the amount of tributary runoff, and to yearly seasons by means of coaxial graphical correlat

ISSN:0043-1397    

DOI:10.1029/WR009i006p01543

年代:1973

数据来源: WILEY

摘要:

The mixed Lagrangian and Eulerian approach is proposed to study the thermal and hydraulic performance of cooling ponds that are used mainly to dissipate the waste heat from power plants into the atmosphere. The hydraulic behavior of the cooling pond is analyzed by the Eulerian method, and the Lagrangian approach is used to study the thermal distribution, ‘Isotime’ lines are obtained by numerically solving the governing hydrodynamic equations. The Lagrangian temperature is obtained by solving the energy equation either numerically with the fourth‐order Runge‐Kutta method or analytically with the linearization of the net heat flux at the water surface. The Lagrangian temperature is then converted to the Eulerian temperature through the isotime lines. This model is applied to predict flow patterns, isothermal lines, and discharge temperature for a cooling pond in the southwestern United

ISSN:0043-1397    

DOI:10.1029/WR009i006p01555

年代:1973

数据来源: WILEY

摘要:

The relative, magnitudes of surface cooling and lateral diffusion and advection from a thermal effluent are investigated. Data have been gathered at Nine Mile Point, east of Oswego, New York.,An estimate of the energy balance of this plume is made. The effective lateral diffusion coefficient obtained from this budget is larger than most values published. Also, surface cooling is suggested to be larger than that estimated by a Dalton type formula. This suggestion is supported by an estimate of advection of sensible heat above the plume. A modification of the temperature of the air over the plume is indicated by the data, although no increase in vapor pressure is observed. However, the variance of the vapor pressure in both time and space suggests a high degree of turbulence.

ISSN:0043-1397    

DOI:10.1029/WR009i006p01565

年代:1973

数据来源: WILEY

摘要:

Energy balance measurements of evapotranspiration from a young Douglas fir forest are reported for a period of 18 days in July 1970 when soil water was not limiting. Peak daily evapotranspiration rates characteristically occurred 2–3 hours after solar noon, and evapotranspiration showed a short‐term independence from net radiation. This behavior is interpreted as being a consequence of the large forest roughness. Daily evapotranspiration and net radiation were, however, well correlated. Values of surface diffusion resistance calculated from Monteith's combination formula are presented. Daytime values showed significant day‐to‐day differences, and an attempt to define a potential evapotranspiration rate by assuming a constant daytime surface resistance was not successful. Comparison of evapotranspiration measurements with a potential evaporation formula for wet surfaces developed by Priestley and Taylor suggests that evaporation of intercepted water proceeds 20% more rapidly than evapotranspiration from the nonwetted

ISSN:0043-1397    

DOI:10.1029/WR009i006p01579

年代:1973

数据来源: WILEY

摘要:

The effect of fog intensity and leaf shape On water storage on leaves was studied by using a simple fog wind tunnel and leaves of aluminum and plastic. Test equipment was designed to allow quantification of the chosen variables rather than to duplicate natural conditions. Two intensities of fog were produced, and drip was measured from leaves of five different shapes. Fog intensity effects tended to obscure weaker leaf shape effects in the tests. Drip measurements were reasonably close to values predicted by calculation using an exponential equation based on fog flow and leaf storage capacity. Results indicate that the method of estimating fog drip could be useful when appropriate climatic and vegetative characteristics are known.

ISSN:0043-1397    

DOI:10.1029/WR009i006p01591

年代:1973

数据来源: WILEY