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An elementary exposition of choice criteria for social investment is presented. The two causes for discounting the future benefits, time preference and opportunity cost, are discussed. The general reasons for special methods of measuring benefits are brought out. The subsequent discussion is a more detailed analysis of the application of these general principles, together with some remarks on the measurement of costs. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The provision of navigable inland waterways has been an important part of the water resources development and conservation program of the United States. Two problems, one public and one private, arise in connection with such waterways: (1) the determination of optimal scale of waterway projects in terms of length, depth, and width; (2) the selection by private operators of the best equipment (boats, barges, and their configuration) to be used on particular water-ways. This paper provides functional relationships that permit prior evaluation of the effects of waterway scale variables on ton-mile costs of cargo transportation. The same relationships can be used to determine least-cost tow configurations for a given waterway. Finally, substitution possibilities between towboat and barge inputs are investigated. [ABSTRACT FROM AUTHOR]

This paper describes the application of systems analysis and digital computer simulation to the control of waterlogging and salinity in West Pakistan. The details of the project are not nearly so important here as the nature of the systems approach and the demonstration of digital computer applicability to civil engineering problems. The history of waterlogging and salinity of agricultural lands in West Pakistan is the by-product of a truly remarkable system of crop irrigation which has been employed in increasing intensity over a period of some 3000 years. During the early part of this century British hydraulic engineers initiated the barrage system of irrigation and began to divert large quantities of water from the mighty Indus River and the five great tributaries that drain the Punjab region of the subcontinent. The economic and technologic aspects of the remedy, a well field of truly heroic proportions, are discussed; the role of the digital computer is seen to be essential to the concept and thrust of an operations research solution. [ABSTRACT FROM AUTHOR]

Two methods are used to detect the presence of methane gas in water from wells in southwestern Louisiana. A commercially developed combustible gas indicator proved reliable when using proper collection and analytical techniques and mathematical formulas, provided no hydrocarbons other than methane are present. Data obtained from a gas-entrapment device showed that methane is the only hydrocarbon occurring in these waters. Values obtained for the quantity of methane present utilizing both methods agree within 10%. To aid the better understanding of the use of these two methods and to demonstrate what physical constants are used, the equations utilized in calculating the amount of methane are derived. [ABSTRACT FROM AUTHOR]

Movement of contaminants from many waste sites into the subsurface water circulation system results in contaminated zones, or enclaves, in the zone of saturation (below the water table). Difficulty in predicting the areal extent of a contaminated zone stems from the multiplicity of factors that need consideration, including: the great variety of waste materials, their range in toxicity and adverse effects; man's variable pattern of waste disposal and of accidental release of contaminants in the ground; man's variable pattern of water development from wells; behavior of each contaminant in the soil, water, and rock environment; ranges in geologic and hydrologie conditions in space; and ranges in hydrologie conditions in time. Two opposing tendencies need to be in focus before an evaluation of contaminated zones is undertaken: (1) the tendency of contaminants to be entrained in groundwater flow and (2) the tendency for contaminants to be attenuated to varying degrees by dilution in water, decay with time, or some other 'die-away' mechanism, and sorption on earth materials. Once a contaminated zone is approximately stable, an increase in concentration may cause it to remain about the same size under some conditions and to enlarge in others, according to combined attenuation effects. Where attenuation occurs only by dilution, the contaminated zone will become enlarged with increased concentration, and, where dilution is also slight, it may become greatly elongated in the direction of groundwater, and perhaps also of surface-water, flow. Where attenuation occurs also through decay or sorption, or through both mechanisms, the contaminated zone may not enlarge appreciably, even if the concentration of contamination is increased. The upper part of the zone of saturation in populated parts of the Earth may be considered as a galaxy in which millions of enclaves of contaminated water are scattered in uncontaminated groundwater. Interspersed with these enclaves are millions of water-supply wells, some of which pump contaminated water or help to disperse it even if it does not reach them. Although too few contaminated zones have been delineated to enable a statistical analysis of areal patterns, an approximation of their patterns of distribution can be deduced. [ABSTRACT FROM AUTHOR]

Studies have been made of the relationship between the rainout of radioactivity in convective storms and three rainfall factors: rainfall volume, storm duration, and rainfall rate. Data were used from four densely gaged sampling networks operated during the spring and summer of 1962-1964 in central Illinois. The network areas ranged from 10 to 6000 mi2 and provided data on both microscale and mesoscale relationships. Analyses of spatial variability showed a trend for the relative variability of radioactive rainout to (1) exceed the storm rainfall variability, (2) decrease with increasing rainfall volume and storm duration, and (3) increase with increasing network size. Investigation of the point representativeness of single measurements of radioactive rainout in a 15-storm sample indicated that an average error of 20-25% is introduced when a single observation is assumed to represent the mean rainout over areas of 10-12 mi2. Correlation analyses indicated that the rainfall at a given point is not strongly related to the radioactive rainout at that point. However, when areal patterns of rainfall and rainout are compared and allowance is made for displacement of high and low centers due to various meteorological influences, a strong association is indicated between the major features of the patterns in most storms. [ABSTRACT FROM AUTHOR]

Naturally occurring stable or radioactive isotopes may be used in some places to identify the origin of saline water that contaminates some coastal aquifers. In a recent study to determine the origin of saline water in the Ocala Limestone aquifer near Brunswick, Georgia, the following sources were analyzed for C14 and deuterium concentrations: potable water from the Ocala Limestone, contaminated water from the Ocala Limestone, saune water from the underlying Claiborne Group, and nearby ocean water. The chloride concentration of the groundwater ranges from about 25 ppm in the potable water to more than 2000 ppm in the deeper part of the Claiborne Group. From an interpretation of piezometric maps and other hydrologic data, previous investigators had concluded that the source of the contaminating water was the Claiborne Group and not the nearby ocean. The essentially uniform range of low values of −965 to −987‰ of the modern standard (National Bureau Standard C14 oxalic acid) for the C14 activity of the groundwater samples (regardless of the degree of contamination) is in agreement with this conclusion. If recent ocean water, which had a C14 value of +285‰, were the source of contamination, the contaminated water would have had a C14 activity higher than the activity of the fresh water. Deuterium analyses are not inconsistent with the interpretation that water from the Claiborne Group, rather than recent ocean water, is the source of the contaminating water. The concurrence of the hydrologic and the isotopic data in this area where the hydrology is well known suggests that isotopic analysis may be used to identify the origin of water in different portions of a hydrologic environment. [ABSTRACT FROM AUTHOR]

An analysis was made to determine the amount of annual and seasonal water yield, flow duration, and peak flow frequency for seven major physiographic units in the northeast. AU watersheds (137) in the northeast that were less than 100 square miles in area, that had continuous records from 1940 to 1957, and that were not appreciably affected by regulation and diversion were included in the analysis. In addition, streamflows of four small forested experimental watersheds were compared with average streamflow values of the physiographic units in which they were located. The longest simultaneous record available was for a 3-year period from 1959 to 1962. Results indicate significant differences in water yield between physiographic units as well as between watersheds within units. Water yields from the small experimental watersheds, although based on a shorter and different period of time, were found to correspond closely with average water yields of their respective physiographic units. [ABSTRACT FROM AUTHOR]

Streamflow from small watersheds on the western slopes of the Oregon Cascade Range is strongly influenced by a maritime climate (wet winters and dry summers). Although annual precipitation is high (94 inches in the study area), overland flow is almost unknown. Peak flows result largely from subsurface flow and under conditions in which both retention and detention reservoirs are almost filled during extended periods of low-intensity rainfall. Under these conditions, vegetation appears to exert a minimum influence on high streamflow. Lowest Streamflow occurs from late August to mid-November and may follow a 60− to 100-day period with little or no rain. The dense vegetation of this part of the Douglas-fir region appears to exert its major influence at such times. Removal of vegetation from only 30% of a 250-acre watershed has caused a 12-28% increase in minimum streamflow. On a 237-acre watershed on which 80% of the trees were cut, the increase in low flow was 85%. [ABSTRACT FROM AUTHOR]

The flow of water through a homogeneous anisotropic soil is governed by Darcy's equation in which the velocity is proportional to the imposed hydraulic gradient. The constant of proportionality (coefficient of permeability) is a symmetric tensor of second rank, reducing to a scalar only in the case of isotropic soils. It is shown that for determining the velocity vector from a known hydraulic gradient the permeability tensor ellipsoid should be constructed with semiaxes equal to the inverse of the square root of the permeability values. For determining the hydraulic gradient from a known velocity, the permeability tensor ellipsoid should have semiaxes equal to the square root of the principal permeability values. The fact that two different tensor ellipsoids can be constructed for a given anisotropic soil may produce confusion and give rise to a significant error. Special attention should therefore be given in evaluating the appropriate permeability value to be used in Darey's equation. It is recommended that the ellipsoid used always be the one with semiaxes equal to the inverse square root of the principal permeability values. Permeability tests were conducted on anisotropic sandstone. Cylindrical cores were taken at various directions with respect to a fixed coordinate system, and permeability values were determined in a constant-head permeameter. The values obtained when plotted on polar coordinate paper result in a two-dimensional permeability ellipse. The necessary graphical constructions for determining the direction of the velocity or the direction of the hydraulic gradient from the corresponding tensor ellipses are also given. [ABSTRACT FROM AUTHOR]

The cost allocation method described here, which is for dual purposes or combined electricity water desalination plants, uses exclusively economic data. The method is based on the cost of power and water produced in single-purpose plants and on the application of the cost relationship for a given net output of water and power to the total annual cost of a combined plant. [ABSTRACT FROM AUTHOR]

Comprehensive water resource planning formulates optimal programs, largely investment programs, in a systems context through use of principles of production and allocation economics and operations research. The planning problem entails maximization of an objective function, subject to constraints and to the production function. System design consists of derivation of three fundamental relationships-the cost-input, benefit-output, and output-input functions-and their application to the system under study. The process of system design at field level consists of three major elements: preparation for planning; performance of basic physical, economic, and social studies; and formulating system designs, which in turn involves preliminary screening of development alternatives and detailed systems analysis of the alternatives that survive the screening. Major new techniques of analysis, typically computer oriented, include (1) optimal scheduling methods for the planning task, such as the Critical Path Method and its variants; (2) regional input-output analysis to derive regional economic projections; (3) improved theoretical models and practical methods of data analysis for deriving benefit-output functions, including those for flood prevention, outdoor recreation, and domestic and industrial water supply; (4) models for generating synthetic streamflow sequences and stochastic storage-yield functions; (5) linear programming and rough simulation techniques for preliminary screening of development alternatives; and (6) detailed simulation analyses and response-surface sampling for derivation and study of final system designs. Some of the new techniques can be used feasibly in current planning; others require further development and testing before they can be put to practical use. [ABSTRACT FROM AUTHOR]

Adjustments of water between uses and areas of use is essential for the public interest in economic efficiency because of changing demands for water, differential rates of regional growth, and limited supplies. The physical aspects of water supplies give rise to rather complicated legal rules regarding property right management, particularly where transfers of ownership are attempted between uses and areas of use. Transfers entail effects on third party users, and the present legal restrictions on transfers do not lead to an economically efficient use of water. Application of marginal efficiency conditions to a water transfer and consideration of physical interrelatedness effects indicate that present procedures take into account protection of losers but do not allow for compensation from third party 'gainers.' Conclusions from an economic analysis of the transfer problem indicate that the benefits from the interrelated use before and after the transfer must be taken account of in specification of legal rules. Adoption of such rules would be necessary for efficient market allocation. [ABSTRACT FROM AUTHOR]

Savings in treatment costs to municipal water treatment plants downstream result directly from improved municipal sewage treatment upstream. The maximum return per additional investment dollar is from primary to secondary sewage treatment. The ratio of cost savings to the costs of additional treatment varies between negligible and 0.10. The quantity of withdrawal for municipal water supply required to justify additional upstream treatment costs is of the order of from 16 to 250:1 for small sewage treatment plants and from 10 to 30:1 for large sewage treatment plants, if in-place use and stream quality are of minor importance. If clean streams are desired, the costs of maintaining high stream quality must therefore be justified by in-place uses, such as for recreation and fish and wildlife preserves. In areas where reclamation of municipal waste effluents is feasible, present emphasis on maximizing stream assimilative capacity through minimum waste treatment is poor utilization of water resources. [ABSTRACT FROM AUTHOR]

A comparison is presented of monthly evapotranspiration data obtained by various methods for the valley of the Ruzizi (Eastern Congo Republic). Best agreement was noted for evaporation, as measured with a pan and calculated with Penman's equation. The Blaney-Criddle and the Thornthwaite methods did not have an adequate response to changes in evaporation potential, since temperature and day length varied little. Some improvement was observed with the Blaney-Morin method, which includes a humidity factor. [ABSTRACT FROM AUTHOR]

All available reports of rainfall interception by hardwoods of the eastern United States were reviewed and, where possible, combined. Results from these independently designed and analyzed experiments showed that hardwood throughfall and stemflow vary over a surprisingly narrow range. Combined regression analysis describes the relation between inches of gross rainfall ( P), throughfall ( T), and stemflow ( S) for summer as T = 0.901 P - 0.031, S = 0.041 P - 0.005; for winter as T = 0.914 P − 0.015, S = 0.062 P - 0.005. These equations can be modified for specified forest conditions or for use with seasonal rainfall. Fifteen standard gages were found necessary to sample the growing season throughfall within 5% error limits, and 6 were necessary for the dormant season. Hardwood litter interception, studied inadequately in most parts of the east, amounted to 2 to 5% of the annual rainfall in the southern Appalachians. Applicability of equations to research and to practical problems is discussed as well as need for further research. [ABSTRACT FROM AUTHOR]

A statistical model of turbulence for two-dimensional uniform flow in open channels is developed, and this model is used to derive the vertical velocity profile. This profile is defined by a three-parameter hyperbolic function, with two parameters reflecting the effect of bed roughness and fluid viscosity on the shape of the profile. The third parameter is the mean velocity in the vertical. The hyperbolic function is fitted to velocity data for water in natural channels, a laboratory flume, and air in a wind tunnel. A brief comparison of the hyperbolic function with the logarithmic function is given. [ABSTRACT FROM AUTHOR]

Temperature and hydrostatic pressure disrupt the structure of sea water; both the bulk order and the local order in the hydration atmospheres of ions are affected. These structural changes in turn affect transport processes such as electrical conductivity and viscous flow. [ABSTRACT FROM AUTHOR]

Uneven penetration of soil moisture has been observed after several southern California wildfires. This condition seems to be associated with an organic coating on soil particles that makes the soil hydrophobic. Field sampling shows the 'nonwettable' condition to be wide-spread in chaparral watersheds. [ABSTRACT FROM AUTHOR]

Equipotential and isobar patterns were calculated for the case of flow in a saturated inclined soil slab resting on an impermeable base. Two situations were analyzed, one with both upper and lower ends of the slab closed to flow and another with only the upper end closed. Most of the water flowing through the slab enters and leaves in a surface region near the ends of the slab. For slope length-to-depth ratios greater than about 10, the total flow can be estimated quite closely by treating the slab as an inclined one-dimensional flow system. [ABSTRACT FROM AUTHOR]

Unconfined flow of water to wells is related to anisotropy of the aquifer, changes in the coefficient of storage with time, degree of penetration of the pumping well, and position of the water table. Sluggish response of observation wells to changes of head in the aquifer may lead to erroneous analysis of pumping-test data. The manner and extent to which these factors affect water levels have been studied by field observation, by analytical equations, and by electric analogs. The typical S-shaped curves of log drawdown versus log time, observed around wells pumping from water table aquifers, can be explained by an infinity of combinations of possible flow patterns and observation conditions. Equations developed for artesian flow cannot be used for analysis of tests made under water table conditions unless steady-state conditions have been approached or reached. From a practical standpoint the time required to approach steady flow is much greater than the duration of most pumping tests. Thus if pumping tests are to be used for measuring the hydraulic properties of unconfined aquifers, the boundary conditions attending unconfined flow must be recognized in the analysis of test data. [ABSTRACT FROM AUTHOR]

An analytical solution is developed describing vertical steady flow of groundwater and heat through an isotropic, homogeneous, and fully saturated semiconfining layer. A type-curve method for estimating groundwater velocities from temperature data is presented. [ABSTRACT FROM AUTHOR]

New methods for designing water resource systems are being evolved as part of a general social tendency toward expressing social problems in the formal modes that have hitherto been restricted to scientific and engineering problems. Two general types of model have been fruitful in the field of water resource development: the simulation model and the analytic model. In simulation models temporal sequences of events are reproduced on electronic computers on a time scale in which minutes represent decades, leading to convenient estimates of the consequences of design decisions even in complicated circumstances. In analytic models consequences are expressed as explicit mathematical functions of design variables. Simulations are awkward when a wide range of design decisions has to be evaluated ; analytic models cannot be applied to practical problems without drastically simplifying them. But the two methods can be used in tandem, with analytic models delimiting the range within which simulation is required. [ABSTRACT FROM AUTHOR]

Organizational arrangements for the exercise of controls over surface water flows have taken a wide variety of forms. Political considerations have largely determined the choices between alternatives of private versus public development, state or local versus federal development, and the selection among alternative federal development agencies. Because of variations in the effectiveness of political forces through time and space, the development pattern in almost every major river valley is distinctive to itself. An analysis of control arrangements in a sample of 145 reservoirs indicates that public enterprise has almost entirely replaced private in current developments but that both state and federal water agencies show continuing vitality. The distinctions among levels of governmental control are closely related to the functions performed, with local governments most active in the provision of water supplies; special districts in reimbursable functions; state agencies in nonreimbursable functions; and the federal government in projects including flood-control (and navigation) benefits. [ABSTRACT FROM AUTHOR]

The basic concepts of systems analysis and optimum (least-cost) water pollution control are presented. The equations utilized to describe the time and space variability of dissolved oxygen are presented in a systems analysis context, and their usefulness in this form is discussed. The application of the mathematical model to the control of dissolved oxygen in the Delaware Estuary is given. Recent computer solutions are illustrated, and the sensitivity of the least-cost dissolved oxygen improvement solutions to the rate of atmospheric reaeration is presented. [ABSTRACT FROM AUTHOR]

Three methods to calculate the unsaturated conductivity of soil from its moisture characteristic were tested. Calculated values were compared with direct measurements of conductivity for both sorption and desorption for a sand. Also, comparisons were made for three soil materials. The method of calculation proposed by Millington and Quirk [1959], when matched at the saturated conductivity, gave good results. [ABSTRACT FROM AUTHOR]

The glyceryl half-ester of decenylsuccinic acid (GlOSA) closes tree stomata when sprayed directly upon the undersides of leaves. Regression analysis of streamflow from two small watersheds at Coweeta showed that a 12% reduction in transpiration might be detected as a significant increase in streamflow. Two sprays of 50 pounds of GlOSA in water applied to 30 acres of one watershed from a helicopter produced little deposit on the undersides of leaves and no clear evidence of stomatal closure. Observed increases in streamflow were statistically insignificant. [ABSTRACT FROM AUTHOR]

Over a 23-year period the winter-spring high runoff regimen from a reforested watershed in central New York was compared with that of a nearby agricultural watershed. Techniques for analyzing regimen over a large range of flow and time were developed from Court's half-flow date and duration concepts and selected daily flow data. The techniques revealed that runoff during snowmelt periods is gradually concentrated in a shorter time following reforestation of open lands. There is also a gradual desynchronization with runoff from the agricultural watershed, so that concentrated snowmelt runoff comes later in the season in the years following reforestation. The desynchronization is apparent over the entire range of flow and time studied, from mean daily flows of 7 cubic feet per second per square mile to half of the annual flow, which appears over a period as long as several months. The techniques used are evaluated in terms of their applicability as measures of streamflow regimen and their validity in detecting changes in regimen resulting from changes in land use. [ABSTRACT FROM AUTHOR]

The Cordilleran hot springs of central Chile can be divided into four groups: ( A) Pre-Cordillera springs of variable composition emerging from continental sediments and andesites. Temperature ranges from 22 to 30°C. ( B) Inner Cordillera springs found along a zone of structural weakness indicated by the presence of volcanoes and faults. The waters are rich in Ca, Mg, HCO3, and SO4, and minor elements, Sr, B, V, and Ti derived from marine sediments containing limestone and gypsum deposits. Some of the springs have considerable amounts of Fe and Mn. Temperatures are variable, ranging from 30 to 80°C. ( C) Sulfuric-acid type springs with a temperature of about 85°C.-These waters leach Fe, Mn, and Al from the rocks. ( D) Dilute NaCl springs in the batholith with temperatures ranging from 40 to 75°C. All the springs are near volcanic centers. The origin of the water is discussed, but not all the springs are considered to have contributions from magmatic sources. Some variations in the discharge occur, but the temperature and comparison, so far as can be ascertained, are constant. [ABSTRACT FROM AUTHOR]

Viewed from the perspective of the Moon, we could readily see that water is the most abundant mineral on Earth. About 71% of the spheroid's surface is formed by oceans, another 3½% by polar icecaps, and the remaining 25½%, constituting the land masses, is at various times and places obscured by water in the vapor phase, covered by water in the solid phase, and is draining or storing water in the liquid phase. Where there is life there must be water. Every organism on Earth, plant or animal, is dependent on it. The biologist finds plants, animals, entire ecosystems, adapted to practically every environment on Earth, though ranging widely in abundance and variety: least numerous in the intense pressures of great ocean depths and the intense cold of high mountains and polar icecaps, most numerous where the land surface or ocean bottom is within 600 feet of sea level. Characteristically the terrestrial organisms are adapted to the fresh water that comes from precipitation and occurs in the soil, streams, lakes, and rock materials of the continents and islands. Both plants and animals are adapted to the great variety of environments thus available, ranging from deserts and tundras to rain forests and swamps and lakes. The water quality may range from 'pure as the driven snow' to highly saline or otherwise contaminated; in some environments both the amount and the quality of water change markedly from time to time. The biological adaptations to the available water supply are necessarily also quite varied and include such extreme examples as the kangaroo rat in the southwestern deserts, the lungfish in the ephemeral streams of east Africa, and the brine shrimp in Great Salt Lake. [ABSTRACT FROM AUTHOR]

Conventionally hydrologists have used regression analysis for solving their multivariate problems. Recently other multivariate statistical methods have been advocated. This paper discusses and compares the effectiveness of six methods of analysis: regression, principal component, varimax, oblimax, key cluster, and object. Strengths and weaknesses of each method are discussed, and the combination of principal component regression with varimax rotation of the factor weight matrix is recommended for an initial analysis of multifactor hydrologic problems. [ABSTRACT FROM AUTHOR]

The conjunctive use of nonlinear integer programming and principal component analysis is suggested for specification of a constrained optimal gaging program whose objective is to define efficient estimates of the several annual means. The assumptions in the analysis are restrictive; data from the n sites are presumed to be available for n1 years, and n2 years of additional gaging are contemplated. The observations are presumed to derive from a multivariate normal population with no serial correlation. The method specifies which sites from among the n candidates should be continued and which should be estimated by linear regression. Although the discussion is directed toward hydrologie applications, it should be recognized that the technique is generally applicable to sampling surveys. [ABSTRACT FROM AUTHOR]

The accuracy and precision of two field methods and a laboratory method for determining detergent (alkylbenzenesulfonate) in water have been investigated. Commercially available kits were used for the field methods. A total of 660 determinations were made by two analysts on prepared solutions containing both branched-chain and straight-chain detergents. One of the field methods contains large amounts of negative bias that vary with concentration level. The other field method has poorer precision than the laboratory method but no large amount of bias. [ABSTRACT FROM AUTHOR]

Recent years have seen a marked increase in the rate of investment in facilities for water quality control and a concurrent recognition of the need to program water resource use on a regional basis. This paper outlines the nature of regional water quality systems and presents programming models for several water quality improvement problems. A linear programming formulation of a static improvement in quality is contrasted with a traditional policy for programming improvements; the traditional policy results in a mixed integer problem. The maximization of the ratio of benefits to costs of an improvement program is transformed to a linear programming problem. A stochastic natural environment leads to other programming models. A discussion of the application of least-cost models terminates the paper. [ABSTRACT FROM AUTHOR]

A study was made of the possibility of representing the hourly rainfall process observed at a point by a simple model using a digital computer. The purpose of the modeling procedure is to produce synthetic hourly rainfall data for the Stanford watershed model to make possible long records of synthetic streamflows. The model represents the hourly rainfall process by a sixth-order Markov chain and is shown to be a suitable procedure. Dry periods between storms are found to be longer than dry periods that occur in nature. When used in the Stanford watershed model, the synthetic data produce hydrologic characteristics for a test watershed that are in good agreement with those derived from historic data. [ABSTRACT FROM AUTHOR]

The conceptual model upon which studies of hydrologic relations between unit-source and complex watersheds are based is discussed. Comparisons of measured storm runoff from two complex watersheds with that predicted by combining storm runoff of representative unit-source watersheds in accordance with the conceptual model revealed that the measured values were different from those predicted. Within the framework of the present model, unit-source watersheds cannot be used to predict the effects of land use changes on complex watersheds. If the unit-source concept is to find effective application, an improved model must be developed. Three phenomena that seem necessary in a more realistic model are discussed: (1) Interflow, (2) partial area runoff production, and (3) the influence upon downslope runoff production of runoff from upper slopes. [ABSTRACT FROM AUTHOR]

Large-scale areal variations in low-flow characteristics of streamflow are caused primarily by differences in geology in the 576-square-mile Swatara Creek basin just east of Harrisburg, Pennsylvania. Although the low-flow index (the average annual minimum daily flow) of small streams in the basin ranges from 0 to slightly more than 1.0 cubic foot per second per square mile (csm), the flows within each geologic zone show marked similarity, except where affected by mining, diversion, or other activity of man. These natural average minimum flows are lowest in the area underlain by the Martinsburg Shale and range from 0.01 to 0.10 csm. Moderate average minimum flows of 0.1 to 0.2 csm occur in the areas underlain by sandstone, conglomerate, and shale in the northern mountainous part of the basin; greater average minimum flows of 0.3 to 0.4 csm occur in the zone in the southern part of the basin underlain by the Gettysburg Shale, which consists mostly of coarse-grained sandstone. The variability in the low-flow indices of streams is greatest in the area underlain by various limestones and dolomites, ranging from zero to over 1.0 csm. However, even within this zone of limestones and dolomites there is reasonable consistency to the low flows within each of the several formations. [ABSTRACT FROM AUTHOR]

Schmid and Luthin have proposed a mathematical solution for draining sloping land by evenly spaced ditches that reach to the impermeable layer. Their theory was based on solutions of the Boussinesq equation for the water table in equilibrium with rainfall. The Dupuit-Forchheimer assumptions inherent in the Boussinesq equation lead to an undetermined error in the results. A Hele-Shaw model used to solve the same problem indicated that the error due to the Dupuit-Forchheimer assumption was small for slopes less than 30%. For slopes greater than 30% the mathematical solution gave ditch spacings that were too great. [ABSTRACT FROM AUTHOR]

A four-year study of drainage effluent obtained from 15 tile drainage systems located in the arid San Joaquin Valley of California showed that the concentration of salts and the various ions discharged in the tile effluent decreased, logarithmically, from the time that the tile systems were installed. Regression equations and correlation coefficients are presented for total salts, boron, sodium, calcium plus magnesium, chloride and sulfate ions, versus time from 0 to 12 years of tile drainage system age. The relationships presented could change with more intensive drainage and more liberal use of irrigation water, providing a more rapid trend toward equilibrium. [ABSTRACT FROM AUTHOR]

The estimated average rates of annual solute erosion in 11 important western river basins range from 180 tons per square mile (Willamette basin) to 4.2 tons per square mile (Gila basin). An average rate of 58 tons per square mile is indicated for the entire 545,000-square-mile area drained by the 11 rivers. The wide range in tonnage is the result of a complex of causes, among which differences in geology, gross climatic environments, and activities of man are the most important. Rates of solute erosion are highest in areas of abundant precipitation and runoff, in contrast to rates of suspended-sediment removal, which are characteristically highest in basins subjected to only 10-15 inches of effective annual precipitation. Tonnages of chloride brought into the 11 river basins by rain and snow make up an equivalent of about 1.6 to about 17% of the chloride removed in runoff during an average year. The range of percentages reflects differences in the relative importance of oceanic and continental solute contributions. [ABSTRACT FROM AUTHOR]

The hodograph method for determining patterns of flow of groundwater in a coastal aquifer with a drain requires the treatment of double-sheeted hodograph planes. This many-valuedness does not prohibit the use of Schwarz-Christoffel analysis if the hodograph domain is simply connected. In the two-fluid case of fresh water flowing over stationary salt water the hodograph is simply connected, and the hodograph method is shown to give a solution. This solution was verified by a test that showed a stable interface in the predicted position. [ABSTRACT FROM AUTHOR]

Seepage pressures are part of the neutral or nondeformative stresses acting in a groundwater basin. The reduction of these pressures gives rise to a stress transfer from neutral to effective. The increase in effective stresses is, exclusively responsible for measurable deformations of the land surface. The amount of land subsidence or groundwater recovery from compressible confining layers depends upon the specific storage of the strata and the average head change within them. Expressions for the specific storage are obtained from both consolidation theory and conservation principles of compressible flow. Average head changes are identified on a depth-pressure diagram in terms of head changes in adjacent aquifers and are referred to as 'effective-pressure areas.' The geometry of the effective-pressure area is shown to depend upon the thickness of the compressible strata, the magnitude of artesian pressure decline, the manner in which the basin is developed, and time. These factors are embodied in equations that quantitatively describe the release of stored water from compressible confining layers resulting from their vertical compression in areas of land subsidence. [ABSTRACT FROM AUTHOR]

A new type of forecasting model of great potential for predicting flows in complicated spatial transportation networks is illustrated through application to the forecasting of interregional coal flows by barge over the Mississippi River system. Changes in these flows are related to regional coal production and consumption levels and to the freight charges by barge and rail. The special feature of the model is the great saving on the data needed for its implementation made possible by assuming that transportation patterns will be efficient, i.e., least-cost, for given regional imports and exports. This assumption is incorporated by using the linear programming transportation method to generate individual flows from regional barge imports and exports forecasts by a system of statistically fitted equations. Various applications are illustrated. [ABSTRACT FROM AUTHOR]

Radioactive tracers introduced into the Columbia River in cooling water from the Hanford reactors were used to measure flow times downstream from Pasco, Washington, as far as Astoria, Oregon. The use of two tracer methods was investigated. One method used the decay of a steady release of Na24 (15-hour half-life) to determine flow times to various downstream locations, and flow times were also determined from the time required for peak concentration of instantaneous releases of I131 (8-day half-life) to reach these locations. Flow times determined from the simultaneous use of the two methods agreed closely. The measured flow times for the 224 miles from Pasco to Vancouver, Washington, ranged from 14.6 to 3.6 days, respectively, for discharges of 108,000 and 630,000 ft3/sec at Vancouver, Washington. A graphic relation for estimating flow times at discharges other than those measured and for several locations between Pasco and Vancouver was prepared from the data of tests made at four river discharges. Some limited data are also presented on the characteristics of dispersion of I131 in the Columbia River. (Keywords: Radioactivity; time of flow; Columbia River.) [ABSTRACT FROM AUTHOR]

Nitrogen compounds in natural water are significant in public health, agriculture, industry, and geochemistry. The many sources of nitrogen compounds and the deep involvement of nitrogen in the life processes of organisms makes the study of such compounds difficult. The sources include natural aerosols, precipitation, fixation by micro-organisms in soil and water, decaying organic matter, and animal and industrial wastes, as well as probably undiscovered sources in consolidated and unconsolidated rocks. Nitrogen compounds are both oxidized and reduced by organisms. Some nitrogen compounds are adsorbed on clay. The theoretical end product in water and the compound probably most often determined is NO3−1. The concentration of nitregen compounds ranges from 0.0 to >100 ppm (parts per million) in surface water and from 0.0 to >1000 ppm in groundwater. Seasonal fluctuations occur. Much further research is needed, including improvements in methods of analysis, further investigation of sources, and detailed study of the nitrogen cycle in small drainage basins. (Key words: Geochemistry; quality of water.) [ABSTRACT FROM AUTHOR]

The biodegradable content of organics in aqueous solution can be assessed in two ways: by measuring the change in organic content effected by bacterial metabolism; or by measuring the consumption of oxygen by bacteria in effecting the removal of organics. In addition to oxygen, two possible parameters for pollution measurement are thermodynamic energy change and total carbon change. The validity of applying thermodynamic concepts to biological systems is questioned. Total carbon changes during the process of biological oxidation are considered to offer an excellent potential as a measure of biodegradable organic content. The use of carbon as a parameter in the context of the two analytical procedures derived at Rice University affords a flexibility in selection of technique based on the required precision of results. (Key words: Pollution measurement; oxygen demand; bacterial synthesis.) [ABSTRACT FROM AUTHOR]

The stomata of plant leaves constitute a main regulating system of the transpiration process. Biologists have suggested a turgor mechanism to explain stomatal movement. The functions of the mechanism are quantitatively described by an osmotic water transfer theory and/or the active water transfer theory in the guard cells. Based on the active water transfer theory and the observations of stomatal movement under various conditions of H2O, CO2, and light, a conceptual model of the stomatal control mechanism is proposed. Transfer functions of the mechanisms characterizing the changes in turgor pressure have been derived. The entire system has been organized by the application of adaptive control system theory and has been simulated on an analog computer. The dynamic characteristics have been investigated with consideration of various environmental conditions. (Key words: Computers, analog; plants; soil moisture.) [ABSTRACT FROM AUTHOR]

Plant life processes are related in a complex way to the balance between the water demand of the atmosphere and the availability of water to the plant root. An exploration of the dynamic status of water in the plant is very important. As an approach to an integrated analysis of the dynamic system of water movement through the soil-plant-atmosphere continuum, a simulation model of the transpiration process is presented. Van den Honert suggested the use of Ohm's law describing water flow into, through, and out of plants. In the present study, this hypothesis has been expanded to include an analogous storage factor to deal with the dynamic flow of water in the plant. A set of differential equations and transfer functions is expressed in terms of water suction variables. The dynamic description of the water status in the plant is completed by introducing the system gain, which is a function of both the transpiration rate and the soil-water condition. The dynamic system gain is realized by a method similar to Corbin's method of a computer-controlled adaptive control system. The entire system is then simulated on an analog computer; its dynamic characteristics are investigated with consideration of various environmental effects. (Key words: Computers, analog; plants; soil moisture.) [ABSTRACT FROM AUTHOR]

As a result of advances in high speed digital computers, considerable interest has been shown in the use of a numerical solution of the complete equations of free surface flow to synthesize the unsteady channel and overland flow conditions that occur during a period of runoff. The advantage of this approach is that it provides a logical description of the phenomenon of local inflows entering along a stream flowing at either subcritical or supercritical velocities. This paper shows the feasibility of the approach by comparing the hydrographs and water surface profiles obtained from a numerical solution of the equations with those produced by introducing time varied and spatially varied lateral inflows along the length of a 72-foot-long experimental flume. One of the practical problems found with the numerical technique was a sensitivity to errors in the value of the Manning n used to describe the channel roughness. The difficulties imposed by this sensitivity are discussed and compared with the problems associated with traditional routing methods. (Key words: Flood routing; hydraulics; computers, digital; synthesis.) [ABSTRACT FROM AUTHOR]