摘要:

The technical specification of plant‐water relationships has led to errors in the formulation of response models for water inputs. Consequently, the optimizing procedures making use of these models may have been misleading as to both the practical water application rules recommended and the usefulness of the optimizing procedure. In this paper we show that the distribution of water within the root zone, at least for tea in Malawi, plays an important part in determining response to irrigation. This means that two or more soil moisture state variables will be necessary in the dynamic programing (DP) method of finding the optimal application policy, and this makes DP even more difficult to use in practice than has been previously indicate

ISSN:0043-1397    

DOI:10.1029/WR013i001p00001

年代:1977

数据来源: WILEY

摘要:

The efficiency and equity of the separable costs‐remaining benefits (SCRB), alternative justifiable expenditure, and use of facilities methods of cost allocation are examined. On efficiency grounds, only the SCRB formula satisfied all three efficiency criteria. From an equity viewpoint, no one method allocates costs so that each purpose shares fairly in the savings from multiple‐purpose development. The source of inequity with the SCRB and alternative justifiable expenditure methods arises because either separable costs or specific costs are subtracted from justifiable costs on a 1:1 basis. Conceptual problems in defining capacity preclude the use of facilities method from satisfying the equity objective. An adjustment in the SCRB method is proposed which will enable this procedure to satisfy both efficiency and equity crite

ISSN:0043-1397    

DOI:10.1029/WR013i001p00008

年代:1977

数据来源: WILEY

摘要:

Eight fluorescent dyes (amino G acid, photine CU, fluorescein, lissamine FF, pyranine, rhodamine B, rhodamine WT, and sulpho rhodamine B) were compared in laboratory and field experiments to assess their utility in quantitative tracing work. The properties considered included sensitivity and minimum detectability, the effect of water chemistry on dye fluorescence, photochemical and biological decay rates, adsorption losses on equipment and sediments, toxicity to man and aquatic organisms, and cost. The orange fluorescent dyes are more useful than the blue and green because of the lower background fluorescence at the orange wave band, which permits higher sensitivities to be obtained. Pyranine fluorescence is strongly affected by pH over the range encountered in natural waters, which precludes its simple use in quantitative work. Amino G acid, photine CU, pyranine, and fluorescein all have high photochemical decay rates. Pyranine, lissamine FF, and amino G acid are the dyes most resistant to adsorption, but rhodamine WT, fluorescein, and sulpho rhodamine B also have moderately high resistance. Rhodamine B is readily adorbed by most materials. Rhodamine WT (orange), lissamine FF (green), and amino G acid (blue) are the three tracer dyes recommended; they may be used simultaneously to trace three injection sites with the filter combinations suggested.

ISSN:0043-1397    

DOI:10.1029/WR013i001p00015

年代:1977

数据来源: WILEY

摘要:

Geothermal activity may lead to convection currents in saturated permeable layers within the earth. This article concerns instability criteria for such a flow field in which the fluid flows initially at moderate Reynolds numbers. Supercritical conditions were analyzed by expanding the finite amplitude perturbations through truncated eigenfunctions. This approach yielded expressions for the intensity of transport processes through the aquifer. It was found that mechanical dispersion due to convection motions reduces the intensity of transport processes.

ISSN:0043-1397    

DOI:10.1029/WR013i001p00034

年代:1977

数据来源: WILEY

摘要:

As a part of the interdisciplinary methodology for exploring the characteristic behavior of the hydrometeorological components of the United States, spectral analysis (consisting of spectral density and cross‐spectral density techniques) is employed to provide statistical information in the frequency domain. The spectral density technique is applied to analyze the 5 years of mean monthly time series of atmospheric vapor transport ∇·Q, atmospheric precipitable water ΔW, runoffR, precipitationP, evapotranspirationE, and change in storage ΔSfor 76 drainage basins of the United States, and on an experimental basis, cross‐spectral techniques are tried for these time series in 10 large combined drainage basins. The outcome from the spectral density analysis provides information about the spatial variation in the periodic properties of the ∇·Q, R, P, ΔS, andEtime series over the United States, whereas the cross‐spectral analysis illuminates the cross‐correlation characteristics of the hydrometeorological data in light of the variations in coherence, partial coherence, and leading and lagg

ISSN:0043-1397    

DOI:10.1029/WR013i001p00041

年代:1977

数据来源: WILEY

摘要:

Information on the processes of erosion and sedimentation, while sometimes sufficient for gross estimates of yield, remains inadequate for modern environmental management. Little is known about sequential processes involved in the systems of erosion and sedimentation, and practice and theory require attention to unsteady or discontinuous erosion and transportation as sediments move from source through channel systems with intermittent periods of storage. While climatic and hydrologic variations markedly affect yield, transport and deposition thresholds of erosion of cohesive materials and sequences of such effects remain unclear. Impact assessment requires understanding of the highly variable temporal and spatial character of sediment behavior, which is often correlative with pollutant behavior.

ISSN:0043-1397    

DOI:10.1029/WR013i001p00050

年代:1977

数据来源: WILEY

摘要:

A two‐dimensional vertically well‐mixed steady state intertidal model based upon the law of conservation of mass was developed to describe the distribution of chloride, nitrogen, biochemical oxygen demand, and dissolved oxygen within a geometrically complex estuary having interconnected tributaries and bayous. The model was verified against two sets of independent field data taken under different temperature and flow conditions within the Pascagoula River basin estuary. Application of the model under critical temperature and flow conditions was made to assess present water quality within the estuary and to predict the effect of alternate wastewater management methods on the water quality within the estu

ISSN:0043-1397    

DOI:10.1029/WR013i001p00055

年代:1977

数据来源: WILEY

摘要:

Previously, a new mathematical model based on the ‘tension center’ or ‘strain nucleus’ concept was proposed by the author for the response characterizing flow in a confined aquifer undergoing three‐dimensional consolidation. The new approach differs fromBio's[1941] in that it leads to the development of a unique integrodifferential equation for the pressure head decline occurring within the porous system. The consideration of the horizontal strain components results in a conceptually simple modification of the classical diffusion equation to which a further integrodifferential term accounting for the three‐dimensional effect is added. In the present paper the new equation of flow is solved in a pumped artesian aquifer enclosed in a half space by an iterative finite element technique. It is shown that in shallow and relatively thick units (withW≃ 0.5, whereWis the ratio between the average depth and the thickness of the aquifer), downward vertical components of flow develop and that the average drawdown deviates moderately from the Theis solution and is no longer uniquely represented against the dimensionless time. The three‐dimensional effect produces an additional soil compression which retards the piezometric decline. At large values of time the horizontal strain components vanish, the diffusion equation holds, and the solution becomes parallel to the Theis profile. As a major consequence the traditional aquifer tests can still be applied to assess the formation permeability, but they yield a 40% overestimate of the elastic storage coefficient. In deeper units (W>0.5) the importance of the three‐dimensional effect diminishes, is already small whenW= 1, and becomes negligible forW≥ 2. In this case the diffusion equation and its solutions are sufficiently accurate. From a practical standpoint the quantitative results given herein are limited by the condition that a mechanically homogeneous and isotropic hal

ISSN:0043-1397    

DOI:10.1029/WR013i001p00062

年代:1977

数据来源: WILEY

摘要:

This paper develops a methodology for solving the problems of conjunctive use of a large‐scale complex groundwater system, a network of streams, and reservoirs all interacting with one another. Decomposing the model of a large‐scale aquifer system as well as that of a stream network into interacting submodels provided an improved mathematical model of the entire physical system. A theorem is proved that establishes the necessary conditions for the existence of a solution to the optimal control problem associated with the management of the groundwater system. A sample problem was formulated in which the options of groundwater operations and surface water supply are conjunctively utilized to meet the water needs of several water users in a basin. The management problem was solved via decomposition and multilevel appro

ISSN:0043-1397    

DOI:10.1029/WR013i001p00069

年代:1977

数据来源: WILEY

摘要:

The physical system this paper deals with is a river basin with multiunit aquifers and interconnected streams. The problem was how to model this complex system mathematically and then to represent it in terms of its response to stress in the form of pumpage and recharge. The system responds to pumpage in two ways: as drawdown or as flow between streams and aquifers. A hierarchy of linear mathematical models for a large‐scale physical system response to stress was developed. For the system response an explicit mathematical expression was used to couple the physical system with the formulation of a management model. The models developed in this paper were successfully tested on a case study of the Fairfield‐New Baltimore area at the lower part of the Great Miami River in southwestern O

ISSN:0043-1397    

DOI:10.1029/WR013i001p00078

年代:1977

数据来源: WILEY