bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistics of heights of various auroral forms from Southern Norway: Second communication
Authors: Störmer Carl
Published: February 2008

(1) Introduction—In a short paper published in this Journal in December, 1946, I gave the results of 12,330 measurements of height of polar aurora observed in Southern Norway during 1911–44. The present paper deals with the statistical work undertaken since that publication.

If we compare the diagram of height (Fig. 1) in the above‐mentioned paper with the corresponding one from my expedition to Northern Norway in 1913 [see 1 of “References” at end of this paper], one of the essential differences is that the aurora in Southern Norway occur at much greater heights than those in Northern Norway. There are two reasons for this. First, certain aurora occurring in the Earth's shadow during years of great solar activity as rays and red diffuse surfaces [2], often reach great heights (from 300 to 700 km) and are seldom observed in Northern Norway. Second, the auroral rays in that part of the atmosphere lying in sunshine—which have only once been measured in Northern Norway [3]—have a position very much higher than aurora in shadow, as already pointed out in my paper on sunlit auroral rays published in 1929 [4]. This difference is clearly seen in Figure 1, where the 12,330 heights from my first paper of 1946 are split into heights of aurora in shadow (left) and aurora partly or completely in sunlight (right) [5]. For each kilometer the measured heights are distributed as points along the corresponding horizontal line at approximately equal distances. The same remark applies to the other Figures in this paper.
Seventh Pacific Science Congress, New Zealand, February, 1949
Authors: Beagley J. W.
Published: February 2008

An outline of the topics to be discussed at the Seventh Pacific Science Congress in the Division of Geology and Geophysics is as follows:
Apia Observatory April to June, 1948
Authors: Gerard V. B.
Published: February 2008

(Latitude 13° 48′.4 S., longitude 171° 46′.5 or 11h 27m.1 W. of Gr.)

April 6–7—A sudden commencement of 18 gammas in H at 03h 58m GMT, April 6, introduced a period of mild disturbance lasting until 16h 51m when a large positive bay in H, with rapid irregular oscillations superimposed, commenced. The bay lasted until 18h 22m and was terminated by a rapid fall of 42 gammas in H over a period of ten minutes. Further rapid oscillations continued to about 08h 30m, April 7, with minor activity persisting for some hours afterwards. K‐index 5 was recorded during the sixth and seventh three‐hour periods of April 6.
A summary of the results of the recent magnetic survey of Great Britain and Ireland conducted by professors Rücker and Thorpe: Part I. On the accuracy of the delineation of the terrestrial isomagnetic lines
Authors: Rücker A. W.
Published: February 2008

My friend Dr. Thorpe and I have completed a Magnetic Survey of the United Kingdom of Great Britain and Ireland, of which a full account has recently been published in the Transactions of the Royal Society. I do not propose in this article to give a detailed description of our work, but there are certain points which we have been able to discuss with unusual fulness, an account of which may be interesting.

observations have been made by us or under our direction at 882 places in the British Isles. There is therefore one station to every 139 square miles of land area.
On the distribution of magnetic observatories over the globe
Authors: Schmidt Adolf
Published: February 2008

The first and most important object being to investigate the main features of terrestrial magnetism in its totality, the points of observation evidently should be disposed as uniformly as feasible. This holds, whatever general problem may be pursued: that of establishing the average magnetic condition, or the secular variation; of observing regular oscillations or disturbances. For special problems, which certainly should not be neglected, but are, in immediate importance, second to the main problem, it may be desirable or necessary to condense stations in certain localities, but it is not here contemplated to enter upon the discussion of special questions.

The existing observatories are far from satisfying the above demand. The great majority are on European ground; i. e., within
of the earth's surface. Of the others, the southern hemisphere contains three, none of them south of lat. 38°. The immense surface of the Pacific, too, is entirely devoid of them. The defects of this arrangement, though they have less influence in the case of phenomena (as e.g., the daily variation), which depend mainly, though not entirely, on latitude, become more noticeable, as the phenomena vary likewise in longitude. It is immaterial whether the results of the observatories be treated simply statistically and comparatively, or a generalization be attempted graphically or by computation. The one way or the other may be better adapted to the individual problem, yet upon the selection of the particular method to be employed can not depend the maximum reliability of the results deduced from the available data in a given case. The lack of uniformity in the distribution of magnetic stations would lead us to expect rather uncertain conclusions with regard to the earth's magnetic action, unless in a special case some law should appear simple and undisturbed. For this very reason, on the other hand, a marked improvement in the results might be hoped for, by a judicious disposition of but a few stations within the area not covered hitherto.
Erdmagnetische Observatorien und Electrische Bahnen
Authors: Eschenhagen M.
Published: February 2008

Bei der grossen Ausbreitung, welche in neuester Zeit der Betrieb elektrischer Bahnen im Stadtverkehr, sowie auch zur Verbindung mehrerer Orte unter einander gewinnt, scheint die Zeit nicht mehr fern, dass die Beobachtungen der erdmagnetischen Erscheinungen durch jene Betriebe mindestens sehr beeinträchtigt, wenn nicht ganz verhindert werden.

Zu Washington und Toronto (Canada) ist dies bereits der Fall, wahrend in Deutschland eine ganze Reihe physikalischer Universitäts‐Institute an der Ausführung magnetometrischer Messungen verhindert und die Beobachtungen an Galvanometern wesentlich auf unempfindliche Instrumente beschränkt sind.
Nonstructural measures for flood control
Authors: James L. Douglas
Published: February 2008

A workable procedure is devised for incorporating optimal amounts of nonstructural measures in flood‐control planning, determining proper project timing, and providing review as new developments unfold. Optimality is based on the economic efficiency criterion, or minimizing the sum of the four flood control cost components: flood damage, structural measure cost, the cost of floodproofmg, and the cost of land use adjustment. Optimum timing is estimated by minimizing independently the total cost in successive 10‐year stages. Periodic review is obtained as the plan for each upcoming stage is reviewed before it is applied. The technique was used to analyze a small watershed in Sacramento County, California, and it produced a flood‐control program significantly less costly than that obtained by current procedures. Structural measures for flood control were found most applicable at the two extremes of extensive agricultural or urban damages. Nonstructural measures were favored in situations involving rapidly expanding urban development suffering fairly frequent flooding or unusually costly structural measure construction. Residual flood damages were found to increase with time even after the optimum combination of structural and nonstructural measures was applied.
Role of storm surveys in small watershed research
Authors: McGuinness J. L. , Harrold L. L.
Published: February 2008

A local severe storm was studied to determine the feasibility of using storm survey techniques on small areas. The areal distribution of storm rain amounts was well defined. An indirect measurement of peak runoff was made, and a probable hydrograph was synthesized for a 1030‐acre watershed near the storm core. The survey technique is recommended as a supplement to the more conventional hydrologic research methods.
Characteristics of recession flows from small watersheds in a semiarid region of Arizona
Authors: Brown Harry E.
Published: February 2008

Recession flows from eight small watersheds in central Arizona are described and differentiated on the basis of watershed precipitation and vegetative cover. Average or ‘master’ curves were prepared for each watershed and described in terms of standard deviation and coefficient of variation of the slopes. Duration of master recessions, which varied from 1 to 23 hours, depended on season and vegetation type. Maximum peak discharges, which varied from 30 to 125 csm, usually came from summer rainstorms. The steepest master recession slope was 1.6 on an upper woodland watershed for summer storms; the most gradual was 0.1 for a pine forest watershed for winter‐spring storms.
Wells in homogeneous anisotropic aquifers
Authors: Hantush Mahdi S.
Published: February 2008

When the hydraulic conductivity of an aquifer is a function of direction only, the aquifer is referred to as homogeneous and anisotropic. Anisotropic aquifers are a common occurrence in nature. The effect of anisotropy on the flow of groundwater has been of concern to many hydrologists. Nearly all solutions of flow problems now available do not take into consideration such effects. The process of obtaining such solutions, however, can be used to obtain solutions for problems in homogeneous and anisotropic aquifers. Boundary‐value problems describing the flow in homogeneous anisotropic mediums may be changed by using a simple transformation of coordinates to problems whose solutions are either available or can be obtained through the usual processes of mathematical analysis. Although the process of carrying out the transformation to completion is routine to hydrologists who are versed in mathematical analysis, it is not routine to many active and experienced hydrologists. Solutions are presented herein for the drawdown around wells in homogeneous anisotropic aquifers which, during the period of pumping and the subsequent period of recovery, may be assumed for all practical purposes to be infinite in areal extent. (Key words: Groundwater; hydraulics; wells.)
Broad horizons in water resource planning and investment
Authors: Howe Charles W.
Published: February 2008

In spite of vastly expanded knowledge and computational abilities available in the planning of water resource systems, the scope of most planning efforts remains too narrow. It is argued that planning efforts must be broadened in three ways; (1) geographically, to take into account not just hydrologic interdependencies but the wider range of market and financial relationships; (2) between public and private sectors, to assure that public investments yield sufficiently high returns; (3) to encompass all relevant alternatives, both technological and institutional, for attaining the objectives of development. Examples are given from various water resource areas of the costs of failing to use sufficiently broad horizons in planning.
Measurement of hydraulic and sediment transport variables in a small recirculating flume
Authors: Rathbun R. E. , Guy H. P.
Published: February 2008

An evaluation of techniques for measuring the hydraulic and sediment transport variables in a small recirculating flume showed that (1) the average depth of flow over a ripple bed could be determined adequately by measuring the difference between the water‐surface elevation and the sand‐bed elevation at a large number of positions and averaging the results; (2) the water‐surface slope could be determined easily and accurately from a series of piezometers with taps positioned at 1‐meter intervals along the flume center line; (3) the sediment transport rate was determined by passing all the water‐sediment mixture through a trap covered with screen fine enough to hold the sand. The transport rate varied considerably (10‐fold range) with respect to time. The following transport phenomena were noted: (1) there was no particle movement on the plane bed before ripple formation; (2) the mean velocity for cessation of particle movement (on the ripple bed) was about one‐half that at which first movement occurred (on the plane sand bed).
Evaporation from large deep lakes
Authors: Morton Fred I.
Published: February 2008

Derived insolation and water budget evaporation data for Lake Superior and Lake Ontario are analyzed in terms of both the regional and the water surface energy balances. The results indicate that the seasonal pattern of evaporation is governed by heat storage changes, and that these changes are closely associated with atmospheric energy export from the lake. This finding provides a physical basis for the simple empirical relationships between monthly evaporation and island‐to‐mainland temperature differentials that are developed from the water budget evaporation data. Substantial atmospheric energy export, a concomitant of heat storage changes, reduces the energy available for evaporation. Therefore, evaporation from a large deep lake is less than that from a large shallow lake under comparable climatic conditions. The analysis also provides speculative reasoning and evidence to indicate that evaporation from a large deep lake is closely related to the radiant heat transfer to the sky.
An optimization method for branching multistage water resource systems
Authors: Meier W. L. , Beightler C. S.
Published: February 2008

Several optimization procedures have been proposed for the analysis of complex water resource planning problems. One of these techniques, dynamic programming, has been limited in its applicability to river basin systems, because these systems are nonserial and dynamic programming is by nature a serial procedure. Recently developed methods are discussed and illustrated with example problems for decomposing the nonserial river basin system into equivalent serial systems amenable to analysis by the dynamic programming method.
Sediment transport of streams in the Washita River Basin in Caddo and Grady Counties, Oklahoma
Authors: Allen P. B. , Welch N. H.
Published: February 2008

Sediment yields for nine experimental watersheds, whose drainage areas vary from 26.0 to 3290 square miles, were related to the geology in the watersheds. Yields from watersheds with mixed sandstone, siltstone, and shale geology were higher than for watersheds where the geology was predominantly sandstone. The highest yield rate was 29.7 inches per 1000 years for a mixed geology watershed, the lowest yield rate being 1.32 for a sandstone watershed. Stream channel shape was found to be related to the material in transport. Streams with large sand loads have wide, shallow channels, whereas streams with a predominantly silt load have narrow, deep channels. The correlation between the temperature of the flow and sediment concentration was +0.93. Several total load predictions made with the Colby and modified Einstein procedures were compared with those made with the Brooks total suspended load equation when field‐determined sediment z values and velocity k values were used. Computations by the modified Einstein and Colby method compared favorably with those made by the Brooks method.
Annual hydrologic response to watershed conversion from oak woodland to annual grassland
Authors: Lewis David C.
Published: February 2008

A 12‐acre experimental watershed in the Sierra Nevada foothills of central California has been subjected to intensive range management practices after a six‐year calibration. The treatment consisted of chemically killing a dense stand of oak trees and brush to improve forage production. An adjacent untreated watershed, which is geologically and hydrologically similar, provides a means of evaluating the annual hydrologie response. Streamflow comparison shows an average annual increase of 4.5 inches in water yield. Inflow‐outflow analysis shows a corresponding decrease in consumptive use from an average of 20 inches per year to 15 inches per year. The change in consumptive use is demonstrated in an annual water yield prediction model and in the relationship of consumptive use to precipitation. Estimates of annual potential evapotranspiration from climatological data are higher than measured consumptive use. Two methods for predicting annual consumptive use show close agreement with measured values for both the oak woodland and the annual grassland.
A test of the statistical theory of meander formation
Authors: Thakur T. R. , Scheidegger A. E.
Published: February 2008

The statistical theory of meander formation ascribes the meandering of stream channels to the hypothesis that a river has a Gaussian probability to deviate by an angle dΦ in progressing an elemental distance ds along its course. This paper aims at checking this hypothesis. Taking three cases, the Salt Fork Vermilion River in Illinois, the Assiniboine River in Canada, and, as an interesting comparison, a ‘river’ (Hadley Rill) on the Moon, it was indeed possible to show that the probability in question is Gaussian, using pertinent statistical tests. Our study can therefore be said to confirm to this extent the probabilistic view of meander development.
Dynamically Similar Motion of Two Miscible Constituents in Porous Mediums
Authors: Raats P. A. C. , Scotter D. R.
Published: February 2008

This study concerns the simultaneous motion of pairs of miscible constituents in porous mediums. Geometrically similar porous mediums are considered, and conditions for dynamic similarity are sought. It is found that in general the constituent pairs must have the same Schmidt number. Fortunately, this restriction does not apply if the inertial terms in the Navier‐Stokes equations are negligible. Two special cases are considered: (1) steady, creeping mean motion, and (2) oscillatory mean motion. It is pointed out that the dispersion arising in the first case can often be described macroscopically in terms of a dispersivity, and it is shown that such a dispersivity must be a unique function of the microscopic Peclet number. Some theoretical and experimental examples of this dependency are discussed. In the second case, the dispersion at appropriately scaled positions and times will also depend upon the dimensionless amplitude of the displacement.
Discussion of ‘Mathematical Assessment of Synthetic Hydrology’ by N. C. Matalas
Authors: Young G. K.
Published: February 2008

I wish to comment on the paper by N. C. Matalas, ‘Mathematical Assessment of Synthetic Hydrology,’ with regard to calculating the coefficients of equation 13.

Assume that the cells of M0 and M1 are directly derived from data. This implies thatA may be found using equation 16, which leaves the solution of B as the item of interest. Define C = M0 − M1M0−1M1t; thus, C = BBt. Matalas demonstrates that B is not unique. The fact that C is symmetric permits a simple and direct solution for B, which avoids the application of principal component analysis.
Lakeshore Property Values: A Guide to Public Investment in Recreation
Authors: David Elizabeth L.
Published: February 2008

A study of lakeshore property values in which land and improvement values were regressed against attributes of the site and lake to determine the importance of the various characteristics in predicting property values indicates that swampy or steeply sloped banks are negatively correlated with value, whereas water quality, proximity to population centers, and the presence of many other lakes in the area are positively related to value. No significant relationships were discovered between land values and the amount of public land in the vicinity or the degree of fluctuation in the lake level. Property values approximately doubled in the ten‐year period of the study. By suggesting characteristics that seem to be in greater demand, the study provides information to guide some of the decisions about where to spend the limited public budget for waterfront recreational facilities.
An Implicit Method for Numerical Flood Routing
Authors: Amein Michael
Published: February 2008

There is great need for fast and accurate methods for the numerical solution of the equations of unsteady flow, which play an important role in the field of water resources. An implicit method which is both fast and accurate can be established based on (1) a centered difference scheme for representing the primary differential equations in finite difference form, and (2) simultaneous solutions of the finite difference equations for each time step. The difference equations constitute a system of nonlinear algebraic equations that can be solved on a digital computer by rapidly convergent procedures based on the generalized Newton iteration method. Application of the implicit method to the movement of floods in long channels confirms the efficiency and accuracy of the method.
Water Level Fluctuation in Evapotranspirometers
Authors: Van Hylckama T. E. A.
Published: February 2008

Eleven plastic lined evapotranspirometer tanks were constructed near Buckeye, Arizona. The levels of the artificially maintained ground water in these instruments show distinct diurnal fluctuations. On bare tanks or on vegetated tanks that are not transpiring, this fluctuation is highly correlated with diurnal and semidiurnal atmospheric fluctuations. Two possible reasons for such response are discussed: There might be air bubbles in the saturated zone, or it might be caused by the flexible plastic lining of the tank. The barometric efficiency is about 40%. On vegetated tanks that are transpiring the water level and barometric curves are out of phase, but if the water levels are corrected for atmospheric pressure fluctuations a curve appears that represents the hourly rate of water use. The results may be important in the interpretation of transpiration well data.
Intrinsic Permeability of Hydrological Porous Mediums: Variation With Temperature
Authors: Greenberg David B. , Cresap Ronald S. , Malone Terry A.
Published: February 2008

Experiments designed to measure the intrinsic permeability of hydrological porous mediums have shown that in certain cases the permeability itself varies with temperature and is not constant, as was previously assumed. For cemented quartz mediums permeabilities were found to vary by as much as 0.5% per degree C over the temperature span (20–60°C) reported in this experimental study. Similar measurements with vitrified mediums showed no appreciable temperature coefficient of permeability. As a by‐product of the investigation a characteristic length parameter, in terms of the laminar (permeability) and inertial flow coefficients, has been used to define a modified Reynolds number for all porous mediums. This length parameter appears to be directly proportional to the mean pore dimension as determined from porosimetry measurements. The data obtained from all samples have been found to correlate well in graphical form and are presented in a generalized friction factor (modified Reynolds number) plot.
Optimal Taxing of Water Pollution
Authors: Upton Charles
Published: February 2008

(1) Within the context of the model, optimal taxes on water pollution do exist; (2) The condition for these taxes to raise revenue sufficient to pay for the cost of low flow augmentation has been derived; (3) The social cost of cleaner water has been derived; (4) The ‘waste’ load discharge method of taxation has been shown to be preferable to the ‘increased permissible waste load method’ when C′F ‐ C < 0; (5) The two schemes have been compared for a special case when C'F ‐ C > 0.
Field Observations Compared with Dupuit‐Forchheimer Theory for Mound Heights under a Recharge Basin
Authors: Bianchi W. C. , Haskell E. E.
Published: February 2008

The rising and falling hydrograph of a ground‐water mound beneath the center of a square or circular recharge basin has been theoretically described using the Dupuit‐Forchheimer (D‐F) assumptions. This study involved field testing these theories at a scale having operational significance.
Simulation of Overland Flow on Short Field Plots
Authors: Foster G. R. , Huggins L. F. , Meyer L. D.
Published: February 2008

Overland flow is a major component in any runoff event where the cultural practices significantly affect the watershed runoff hydrograph. A model based on the kinematic flow theory is proposed that satisfactorily predicts overland flow on very rough, short slopes. The model includes retention storage, provisions for a variable point‐infiltration rate and a variable coefficient of friction, the ‘drying up’ of the upstream end of the slope during recession, and a variable area infiltration rate that is a function of the water surface area during recession. Field hydrographs from fallow erosion‐study plots were analyzed for retention storage and estimated values of the Darcy‐Weisbach coefficient of friction. These results were used in the model to simulate hydrographs that were compared with field hydrographs to test the concepts used in the model. The model with a constant Darcy‐Weisbach coefficient of friction or Manning's n adequately describes overland flow on short erodible slopes. (Key words: Hydrology; overland flow)
Dispersion in Porous Mediums Due to Oscillating Flow
Authors: Scotter D. R. , Raats P. A. C.
Published: February 2008

The existence of irregularly oscillating air flow in soils, induced by turbulence in the atmosphere, and the possible effect of such flow on the transport of water vapor and oxygen in soil, make dispersion in porous materials owing to oscillating gas flow of interest. Theoretical study indicated that, for oscillating flow in geometrically similar porous mediums, the rate of dispersion of miscible fluids can be expressed as a function of two dimensionless parameters, the Peclet number and the dimensionless amplitude of the displacement. Experiments designed to test this prediction included the measurement of the dispersion of oxygen in nitrogen in beds of randomly packed spheres subjected to oscillating gas flow. It was found that defining a dispersivity, analogous to a diffusivity, is meaningful, and that the dispersivity was strongly dependent on both the Peclet number and the dimensionless amplitude of the displacement. Data obtained using different sized spheres verified the conclusions deduced from the similarity analysis. (Key words: Dispersion; evaporation; porous mediums)
Salt Water Interface in a Layered Coastal Aquifer
Authors: Rumer Ralph R. , Shiau J. C.
Published: February 2008

The aim of this investigation was to determine the shape and the position of the interface between the seaward flowing fresh water and the underlying salt water in both the isotropic and nonhomogeneous and the anisotropic and nonhomogeneous coastal aquifers. A transformation for the nonharmonic anisotropic layer was introduced so that the governing equations and boundary conditions in the complex potential plane were satisfied. For the nonhomogeneous layers, the homogeneous mathematical models were superimposed under the same dynamical conditions. Solutions of the flow patterns and interface locations have been presented in dimensionless form. It was assumed that the aquifers were anisotropic or non‐homogeneous only in the two‐dimensional sense. From earlier studies it has been shown that the solutions obtained are valid for both the confined aquifer and the unconfined aquifer when the length of salt intrusion is greater than the depth of the aquifer.
Axisymmetric Seepage through Homogeneous and Nonhomogeneous Porous Mediums
Authors: Jeppson Roland W.
Published: February 2008

Solutions to steady‐state free surface seepage from axisymmetric ponds through homogeneous and nonhomogeneous porous mediums to a drained layer at a finite depth are obtained by finite difference methods. In the formulation of the boundary value problems, the magnitudes of the radial and axial coordinates are considered dependent variables in the plane defined by the potential function and Stokes' stream function. Example solutions are given for seepage through (1) a homogeneous porous medium; (2) a nonhomogeneous porous medium in which the permeability decreases with depth; and (3) a nonhomogeneous porous medium in which the permeability increases with depth. The methods and techniques employed are equally applicable to other three‐dimensional seepage and potential fluid flow problems with axial symmetry and free surfaces. The essential differences in the formulation and solution to other problems will be the boundary conditions. (Key words: Porous mediums; seepage)
Evaluation of Channel Changes in St. Clair and Detroit Rivers
Authors: Brunk Ivan W.
Published: February 2008

Extensive improvements for navigation have been made in the St. Clair‐Detroit River (hereafter referred to as SCDR). It is shown that channel changes have lowered the level of Lake Michigan‐Huron by about 2 feet, bringing about the lowest levels of record in 1964 and 1965. The unrecognized changes in the regimen of the SCDR before 1900 have also resulted in the determination of flows that are much too large. The discharge of Lake Erie and the precipitation in the Erie basin are used to derive more reasonable estimates of the flow of the SCDR before 1900.
Some Comments on Regionalization in Hydrologic Studies
Authors: Matalas N. C. , Gilroy E. J.
Published: February 2008

At the jth site, a choice must be made between yi, a statistical characteristic of the observed flows, and ŷi, a regionalized estimate of the characteristic, for use in the model for generating synthetic flows at the jth site. The regional estimate is obtained from a regression of y on a set of basin characteristics. If
, then ŷi instead of yi, is used in the generating model, where
and Vii are the variances of ŷi and yi, respectively, and ρ′ is a measure of the interstation correlations. This criterion is shown to be independent of the jth basin characteristics. The criterion is a function of the jth basin characteristics if the data at the jth site are not used in developing the regression relation. For an ungaged site, ŷi may be obtained with variance that depends upon the basin characteristics at the jth ungaged site. (Key words: Statistics; regionalization; synthesis)
Further to the Hydrologic Importance of Transpiration Control by Stomata
Authors: Van Bavel C. H. M.
Published: February 2008

An exchange of views on the above subject [Idso, 1968; Lee, 1968] revolves principally around results of several experiments carried out by me and former colleagues. Some clarifying comments appear in order, since all relevant details were not published.

A general view must admit that, together with a number of internal and external conditions, leaf stomata determine the rate of transpiration. From a hydrologie or an engineering view, however, what matters is whether this role is of consequence. The issue can be settled only by a study of the transpiration from naturally exposed canopies of vegetation, of their atmospheric environment and, simultaneously, of the transpiration resistance of the leaves. Generalities derived from theoretical or simulation studies cannot supply the answer, and I agree completely with similar comments made by Idso [1968]. Experiments in which vegetation is wetted by rain or artificially cannot be used as evidence, unless the complete energy balance is simultaneously studied. Experiments involving singly exposed individual plants cannot inform us by simple analogy about the transpiration of natural stands.
Measurement of Small Surface Displacements Induced by Fluid Flow
Authors: Davis Stanley N. , Peterson Frank L. , Halderman Allan D.
Published: February 2008

Fluid flow to wells produces strain that has been measured as horizontal, vertical, and rotational displacements of reference points fixed on the ground surface. Most linear displacements measured were between 1 and 100 microns, and angular displacements were a few microradians. Of the various devices used to make measurements, a horizontal extensometer proved to be the most accurate and versatile. Most measurements were made of effects produced by pumping wells for 5 to 30 minutes. Such effects are almost entirely elastic, except in some geologically recent materials. Deflections of the land surface resembled the theoretical deflections caused by a point load on a plate of infinite extent resting on an elastic foundation. Significant horizontal strain was measured in all materials tested, suggesting that accepted equations for fluid discharge from wells might be modified for special conditions near the wells.
Analysis an evaporation control system on the Sea of Galilee
Authors: Reiser C. O.
Published: February 2008

Water Planning for Israel is conducting field tests to determine the feasibility of applying long‐chain alcohols on the Sea of Galilee for evaporation reduction. Good film covers have been obtained on 280‐acre Lake Zohar with winds up to 15 mph, and a spray system is being installed on Lake Kishon to test a larger lake with stronger prevailing winds. Using meteorological data and estimated evaporation rates for the Sea of Galilee, the reduced evaporation when covered with an alcohol film has been calculated from the added film resistance. The iterative solution of an energy balance equating the reduced evaporation energy to increased energy storage, back radiation, and conduction to the atmosphere gave a 40% reduction of the annual evaporation rate of 300 million cubic meters when applying a film for a 10‐month period. The film produces a maximum temperature increase of 5°C at the surface.
A Correspondence Principle for the Theory of Leaky Aquifers
Authors: Herrera Ismael , Figueroa V. Germán E.
Published: February 2008

A correspondence principle for leaky aquifers in which the storage in the confining layers is taken into consideration associates a nonleaky aquifer with every leaky aquifer. It is valid for long periods of operation. Using this principle, the study of the leaky aquifers is reduced to the study of the corresponding nonleaky aquifers. When the quality of the approximation is tested by applying it to an isolated well, complete agreement with results obtained by other methods is found. The principle is suitable for application to numeric studies of regional evolution of piezometric heads.
Ground‐water movement toward artificial cuts
Authors: Kashef Abdel‐Aziz I.
Published: February 2008

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 only.
Effects of Flood Protection on Land Use in the Coon Creek, Wisconsin, Watershed
Authors: Theiler Donald F.
Published: February 2008

In justifying small watershed projects under Public Law 566, the U.S. Soil Conservation Service (SCS) frequently counts as a benefit the intensified use of agricultural land resulting from increased flood protection. This paper, based on a study of a watershed project in southwestern Wisconsin, shows that actual land use changes were far less than predicted by the SCS. The reasons are less related to the watershed project than they are to changes in farming practices. Questions could be raised concerning the adequacy of project evaluation techniques.
Point Rainfall Frequencies in Convective Storms
Authors: Fogel Martin M. , Duckstein Lucien
Published: February 2008

An exponential relation was developed to describe the spatial distribution of convective storm rainfall in southwestern United States. Given that a storm center has occurred, a geometric distribution was used to describe the frequencies of point rainfall depths. A Poisson distribution was assumed to represent the probability of at least one storm center occurring over a given area a specified number of times during a season. Assuming that the two probability distributions are independent and uncorrelated, maximal and minimal distributions of point rainfall depths were derived. The minimal distribution indicates that with a very high certainty a single rain gage will miss at least one convective storm a year. When compared with frequencies determined from long‐term historical records, the maximal distribution exhibits a similar mean, a greater variance, and lower recurrence intervals for the higher rainfall depths.
Distribution of Interior Link Lengths in Natural Channel Networks
Authors: Smart J. S.
Published: February 2008

Interior link lengths were measured for 10 channel networks with magnitudes between 80 and 200. Nonparametric statistical methods were used to test the hypothesis that link length is independent of link magnitude. Four of the networks show no significant change (5% level) of link length with magnitude. Some of the other networks do have significant changes in link length, but the exact number depends on the nature of the alternative hypothesis. Half of the observed changes were positive and half were negative.
Constrained Random Walk Meander Generation
Authors: Surkan Alvin J. , Van Kan Joseph
Published: February 2008

Analyses of meander data and comparison of models based on von Schelling's theory of random walks for isotropic Gaussian deviations yield constraints satisfactory for simulation of realistic meander paths. Runge‐Kutta solutions of the differential equation for most probable paths modified to ∂2∅/∂s2 + σ2 sin ∂ = 0 exhibit excessive regularity. Calculation of correlation functions, transition probability matrices, and second moments for natural meander data as a function of segment direction reveals important dependency on segment ordering and shows isotropic random walk models to be untenable. Neither the directions, curvatures, nor their changes in natural meanders are Gaussian independent. Necessary constraints on random walk deviations for simulating meanders include a significant positive correlation for adjacent curvatures and directions and often a negative one between the curvature changes. Both result from azimuth dependence in the second moment of the curvature. Empirically, §Δθ(Φrpar; = A + B(Φ − ∂0)2 describes the standard deviation of curvature for directions ∂ near the mean direction Φ0. The application of this directional property of meander curvatures makes possible (1) simulation of realistic meander paths, (2) statistical determination of flow direction, and (3) numerical evidence of a unidirectional flow origin for any meander‐like path.
Institutional Factors Affecting Land and Water Development, Lower Rio Grande Valley, Texas
Authors: Trock Warren L.
Published: February 2008

Among the many institutional factors that complicate land and water development in the lower Rio Grande valley are (1) uncertainties in water rights, (2) a proliferation of special districts, (3) inappropriate water management policies among districts, and (4)numerous governmental entities involved in planning and administering water resources. It is recommended that the people of the valley urge and facilitate an early adjudication of rights. Certainty in water rights will encourage investments in the resource and help to implement needed facilities. Improvements in irrigation and drainage could be achieved by reorganizing the special districts. A master district for the three‐county area may be a logical alternative to the many districts that now exist. Rehabilitation of irrigation systems, including installation of water meters, will contribute to the management of water supplies.
The temporal allocation of ground water—A simulation approach
Authors: Bredehoeft John D. , Young Robert A.
Published: February 2008

Users of ground water are typically interdependent in that withdrawals affect the conditions of water supply experienced by neighboring pumpers. In such cases all costs are not registered on the unit making the withdrawal decision, and the individual user of ground water is encouraged to withdraw water at a rate faster than is socially optimal. Previous attempts to consider the problem of the optimal rate of pumping over time from a ground‐water basin have used a simplified model for the ground‐water system that assumes that drawdowns in response to withdrawals are uniformly distributed through the basin. However, large differences in drawdown commonly occur in developing ground‐water systems. These differences throughout the basin lead to great variations in water costs and perhaps to localized economic and hydrologic failure. We have incorporated a more realistic ground‐water model into a simulation program representing a ground‐water basin system. The effects of two policy instruments, a use tax and a quota, were investigated for a hypothetical basin in an arid region in which irrigated farming was the principal economic activity. A policy of unrestricted use was compared with a policy of regulation for several alternative aquifer developments. Policies that reduced the rate of withdrawal increased the discounted net economic yield.
Route or convolute?
Authors: Overton D. E.
Published: February 2008

Some of the conceptual hydrograph models for routing rainfall excess through a cascade of linear reservoirs have been reexamined. Because of the linearity of these models, convolution of the instantaneous unit hydrograph (IUH) is mathematically identical to synthetic hydrographs obtained by direct routing. Routing, however, has been a more traditional procedure mainly because the mathematics is much simpler and the solution of synthetic hydrographe is more direct. Also, reduction of storm duration in the IUH approach has significant disadvantages. If one chooses a linear cascade model for hydrograph synthesis, direct routing in the traditional sense is more direct, more informative, less tedious, and much less time consuming, and it permits sensitivity analysis of the model parameters as computational trials progress and accomplishes convolution implicitly.
Tritium rainout in the United States during 1966, 1967, and 1968
Authors: Stewart G. L. , Wyerman T. A.
Published: February 2008

Annual weighted average tritium concentration and total tritium rainout for United States precipitation continued to decline during 1966, 1967, and 1968. Arithmetic mean weighted average tritium concentration for 12 network stations decreased about 38% in 1966 compared to 1965; about 35% in 1967 compared to 1966; and about 30% in 1968 compared to 1967. The 1966, 1967, and 1968 values were only 20%, 13%, and 9% respectively, as great as they were in 1963. Tritium data for special samples collected following the Chinese nuclear bomb test on May 9, 1966, and June 17, 1967, indicate that no measureable tritium was added to United States precipitation as a result of these nuclear explosions. Tritium data are presented in both tabular form and on contoured United States maps in order that estimates of the tritium input function from precipitation to hydrologic systems can easily be made.
The flow interval method for analyzing timber harvesting effects on streamflow regimen
Authors: Troendle Charles A.
Published: February 2008

A flow interval method of determining the timing of significant portions of annual strearnflow was applied to the discharge data from five small mountain watersheds (four treatment watersheds and one control watershed) in West Virginia. Different degrees of timber harvesting had varying effects on the interval lengths and occurrence. The heavier cuttings caused an apparent lengthening in the shortest 25% and 50% intervals. In nearly every instance harvesting resulted in a decrease in the length of the longest 1% and 5% intervals.
Evaporation of Water into a Sub‐Zero Air Stream
Authors: Yen Yin‐Chao , Landvatter Gerald R.
Published: February 2008

Evaporation of water into sub‐zero air stream to simulate water surface conditions during North American winters has been experimentally carried out. The study covers an air velocity range from 10 to 160 cm/sec and air temperatures up to 20°C below that of the water surface. The results can be well represented by Num = 12.7 + 0.00288 ReL, where Num and ReL are the Nusselt number for mass transfer and the Reynolds number based on the length of the evaporating surface. This correlation gives a value about two and one‐half times higher than the result calculated from the Bowen ratio.
Hodograph Solution of the Drainage Problem with Very Small Drain Diameter
Authors: Youngs E. G.
Published: February 2008

The hodograph treatment of the drainage problem of uniform vertical fluxes draining to a system of parallel equally spaced cylindrical drains laid in an infinitely deep soil is applied to the case of very small drains. A simple approximate expression allowing the inclusion of the effect of the capillary fringe thickness is derived for the drain radius. Computed results are presented, and these are used in the discussion of experimental results for systems of gappy drains laid in a hydraulic model sand tank.
Use of Topologic Information in Processing Data for Channel Networks
Authors: Smart J. S.
Published: February 2008

The binary digit representation of channel network topology is proposed as an aid to data handling for channel networks. Examples of its use are drawn from the fields of water pollution control and geomorphology.
Application of the Convolution Relation to Estimating Recharge from an Ephemeral Stream
Authors: Moench Allen F. , Kisiel Chester C.
Published: February 2008

A linear model that permits calculation of recharge to the water table from a source of finite width and infinite length uses water level measurements made in an observation well near the source and independently estimated aquifer constants. The method requires determination of the input given the output (water level measurements) and the impulse response as a function of space and time. The latter is derived from the linear equations of groundwater motion for the particular geometry of this study. The input is obtained from the discrete form of the convolution integral by using the synthetic division method and is then summed over the appropriate time period to obtain total recharge. For the particular recharge event studies, results agree satisfactorily with an independent estimate of recharge and demonstrate that the convolution relation has practical application to groundwater flow problems.
Evaporation of Brine: A Field Study on the Bonneville Salt Flats, Utah
Authors: Turk L. J.
Published: February 2008

Evaporation rates were determined for seven brines whose average specific gravities varied from 1.207 to 1.333. Evaporation of the brines ranged from 70% to 9.5%, respectively, of the freshwater evaporation rate. The field data agree exceptionally well with differential vapor pressures over Great Salt Lake brine, measured in the laboratory by Dickson et al. [1965]. Water occasionally condenses on the heavier brines because of an inverted vapor pressure gradient.
Improvements in the Van Bavel‐Myers Automatic Weighing Lysimeter
Authors: Rosenberg Norman J. , Brown K. W.
Published: February 2008

The performance of the Van Bavel‐Myers lysimeter has been improved in two units installed at Mead, Nebraska. The units function according to design specifications (0.01 mm precision; 0.05 mm accuracy) after the following modifications were made: (1) provide drainage to maintain underground portions of the lysimeter in a water free condition, (2) relocate the electrical junctions to assure high electrical resistance between ground and the strain gage load cell, and (3) make mechanical damping devices accessible for cleaning and adjustment.