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A ground-water flow system in southwestern Minnesota illustrates water movement between geologic units and between the land surface and the subsurface. The flow patterns indicate numerous zones of ground-water recharge and discharge controlled by topography, varying thicknesses of geologic units, variation in permeabilities, and the configuration of the basement rock surface. Variations in streamflow along a reach of the Yellow Medicine River agree with the subsurface flow system. Increases and decreases in runoff per square mile correspond, apparently, to ground-water discharge and recharge zones. Ground-water quality variations between calcium sulfate waters typical of the Quaternary drift and sodium chloride waters typical of the Cretaceous rocks are caused by mixing of the two water types. The zones of mixing are in agreement with ground-water flow patterns along the hydrologic section. [ABSTRACT FROM AUTHOR]

In this paper the authors find the optimal allocation of servicing periods to a facility servicing N incoming traffic streams. In our model it is assumed that stream flows are deterministic, that there is a fixed amount of lime lost, τi , when the server switches attention from the ith to the i + 1st stream and that the objective is to minimize time average delay. [ABSTRACT FROM AUTHOR]

A relation between streamflow variables and bar conditions on the Lower Columbia River derived by linear regression analysis on U.S. Army Corps of Engineer and U.S. Geological Survey data leads to the hypothesis that bed-load movement and bar scour are increased by streamflow fluctuation. [ABSTRACT FROM AUTHOR]

The exact equations for the mean range of some normal but autocorrelated variables, of known population means and known linear dependence, are developed. The basic hypothesis was that the exact expression in the general form for the mean range of linearly dependent normal variables is the same as for the normal independent variable, which form was derived from the mean range given by Anis and Lloyd. The data generation method (with a large sample of 250,000 random numbers) was used to assess the differences in mean ranges between the developed equations and the computer results. For three cases-the first-and the second-order Markov linear dependence and the simple moving average scheme-these differences are very small, and they are of the order of magnitude of the sampling errors for the data generation method. The expressions for exact values of mean range are derived for: (1) the general Markov linear dependence model; (2) the first-order Markov linear dependence; (3) the general linear moving average scheme; and (4) the simple linear moving average scheme. [ABSTRACT FROM AUTHOR]

A quantitative evaluation of the effect of ground water pumpage on the Arkansas River in southeastern Colorado using both groundwater and surface-water data has shown that, in at least one reach of the valley, pumping has lowered the water table below the level of the apparently pervious streambed, thereby breaking the hydraulic connection between the stream and the water table. The river is gaining except in reaches where withdrawals of water from the valley fill are large. However, a large cone of depression has formed directly beneath the stream because of continuous withdrawal of about 10 cfs of groundwater at Lamar. The cone extends under the losing reach of the stream without appreciable distortion and has been as much as 12 feet below the streambed. In the 1-mile reach immediately upstream from the wells, the stream lost about 2 cfs during each of three sets of observations. Once the water table is lowered below the streambed, hydraulic connection is broken, and changes in depth to water table have no measurable effect on the rate of depletion of streamflow. The major control on infiltration loss, where hydraulic connection is broken, is probably the permeability of the least permeable layer of the streambed. Studies of stream reaches that have beds with wide ranges of grain size and sorting suggest that the range in maximum infiltration rates is small if the streambeds are undistributed and depth of water in the stream is less than about 1 ft. A maximum infiltration rate of 20 gal/ft2/day is suggested as a reasonable first approximation in the absence of observed rates. [ABSTRACT FROM AUTHOR]

In spite of the enormous hydropower potential of the Columbia River, reasonably full utilization requires extensive upstream storage. Storage is necessary to regulate the great fluctuations in stream flow, which have ranged from a minimum of 36,000 c.f.s. (1937) to a maximum of 1,240,000 c.f.s. Provision for storage, however, poses a baffling problem, contrary to the general notion that reservoir sites are readily available in the mountainous West. Although the engineering and economic factors are favorable at a number of potential sites, political, aesthetic, resource and, above all, regional conflicts have brought action on the storage phase of Columbia River power development to a halt. If the necessary storage can be obtained, the Northwest can meet its enormous electrical energy requirements from its hydropower resources. [ABSTRACT FROM AUTHOR]

The surface runoff hydrograph at the outlet of a watershed is the result of distributed inputs being modified by flowing through the watershed surface drainage networks. In this study a model is proposed by which an outflow hydrograph is synthesized by routing input through a simulated drainage system. The simulated flow system is developed from a flow net. Overland flow is routed through stream tubes formed by pairs of stream lines constructed normal to the contour lines (equipotentials) of the watershed to an intersection with an appropriate surface channel. Channel flood routing is then performed down to the outlet, with the calculated overland flow from each stream tube as lateral input. Optimization of the system parameters is studied with respect to factors calculated from hydrograph moments. By comparison with visual judgments the hydrograph lag and shape factor were found to be possible criteria for optimization. [ABSTRACT FROM AUTHOR]

The solutions of the equations that describe the distribution of biochemical oxygen demand (BOD) and dissolved oxygen deficit (DOD) in an idealized natural stream with a time varying velocity can be obtained intuitively from an extension of the well known solutions, which apply for a constant stream velocity. By introducing the concept of the release time, i.e., the time τ( χ, t) at which the particle of water being observed at point χ at time t was released at point χ = 0, the solution for the time varying flow and velocity follows. The formal solution can also be obtained using the LaPlace transform with respect to the space variable χ. An application of this analysis to the effect of a random component of velocity on the BOD and DOD distributions indicates that the standard deviations of the resulting BOD and DOD distributions are approximately equal to the coefficient of variation of the velocity times the BOD and DOD distributions calculated using the mean velocity. [ABSTRACT FROM AUTHOR]

The increasing role of multivariate statistical techniques, a trend based on the growing availability of computers and on pressures for streamlined representation of multi-dimensional arrays of data, carries with it the responsibility for using efficient techniques to manipulate matrices and arrays. It frequently happens that all records in a multivariate system (of flow records, quality measurements, or whatever) are not equally long, and that some subsets of these records do not present a consistent pattern of correlation when the entire bivariate correlation matrix is reconstructed. If one or more estimate is such that the entire correlation matrix is rendered inconsistent, repairs must be effected before continuing the multivariate analysis. Two algorithms for systematically finding a set of adjustments that satisfy the requirements of consistency are given. Of course, the results are not unique. [ABSTRACT FROM AUTHOR]

An extension to an algorithm for the sequential generation of nonhistoric stream-flow, previously used by Thomas and Fiering, is suggested. The distinguishing features of this model are preservation of (1) normal distribution of annual flows; (2) log-normal distribution of monthly flows; (3) correlation between annual flows; and (4) correlation between monthly flows. This model has been applied to two representative Pacific Northwest rivers. A graphical examination of the results suggests that this model provides an authentic representation of streamflow. [ABSTRACT FROM AUTHOR]

The flow of a stream that is hydraulically connected to an aquifer can be reduced considerably by nearby pumping wells. Pumping such wells will either increase the infiltration from the nearby streams or decrease the natural groundwater flow that would have discharged into the streams if the wells had not been pumped, or effect both processes at the same time. The depletion of the stream flow is an increase to the perennial yield of the sand. Consequently, greater supplies of water can be obtained than would be available as groundwater alone in such systems. Natural as well as artificial streams meeting at approximately right angles are not uncommon in nature. Irrigation and drainage canals, and streams having a trellis drainage pattern, are examples of such an occurrence. Wells for domestic as well as for irrigation use are often installed near such streams. Rational estimates of the rate of depleting such streams by the nearby pumping wells are therefore of practical interest. Formulas for estimating the rate and volume of stream depletion in such systems are developed in terms of extensively tabulated functions. [ABSTRACT FROM AUTHOR]

On the Sacandaga River watershed above Hope, New York, a slow one-directional change in land use and an increase in forest cover have been correlated with a decrease in average annual, dormant season, and April runoff over the 39-year period from 1912 to 1950. In 1912, total forest stand density and the density of conifers on the watershed were probably as low as they had ever been, after widespread logging, insect attacks, and a series of fires. As the beaver population increased explosively from 10 individuals to 20,000 individuals and forest density and crown cover of conifers increased up to 1950, the average annual streamflow decreased 7.72 inches, largely as a result of a 5.18-inch decrease in dormant season runoff. April was the only month showing a large enough decrease in runoff (2.98 inches) to be statistically significant. Also, the average length of time it took for the most concentrated one-half of the annual streamflow to run off increased by 19 days, from 67 to 86 days. The storm of November, 1950, disrupted the associated patterns of forest stand development and streamflow change, returning both to a point nearer their 1912 levels. Continuing mortality of trees weakened or exposed by the storm damage had not permitted the re-establishment of any well defined pattern (by 1962) in either stand development or streamflow, although the changes in quantity and timing of flow parallel the changes in vegetation and largely verify the relationships inferred for the previous period. [ABSTRACT FROM AUTHOR]

Techniques of linear analysis are used to study urban and rural drainage basins as low-pass filters. The frequency passband of the basin is determined in terms of its physical characteristics. This determination is used, in conjunction with the spectral representation of input rainfall, to investigate the necessary response characteristics of rainfall- and runoff-measuring instruments. (Key words: Hydrologic systems; instruments; rainfall; streamflow) [ABSTRACT FROM AUTHOR]

Average annual and seasonal runoff and daily mean discharges at selected flow durations of 137 watersheds in the northeast United States totaling less than 100 square miles were related to selected climatic, topographic, and land-use variables. The most influential variables on annual and seasonal discharges, in descending order, were precipitation, percentage of watershed area in forest cover, elevation, latitude, July mean maximum temperature, and percentage of swamp. Isohyetal precipitation was more highly correlated with average annual runoff than precipitation values from stations closest to the watersheds. The degree of correlation of average annual runoff with average annual precipitation in nonmountainous physiographic units was related to the distance between the precipitation station and the center of the watershed. The proportion of forest cover was correlated positively with runoff, its influence very likely integrating a number of environmental factors that would tend to produce greater runoff. [ABSTRACT FROM AUTHOR]