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Geology topics

Luna Bergere Leopold

Publications and source records attributed to Luna Bergere Leopold.

At least 73 records · Page 4Linked to original sources
USGS1960

The challenge of water management

In a sandy, riverside location in Wisconsin my family has a farm, once abandoned by a previous owner because it would not produce much corn. By the time we bought it for a pittance, only a few remnants of white pine remained from the magnificent stands made famous by Paul Bunyan. The variability of the glacial topography had resulted in an interesting mixture of prairie marsh, swamp woodlot, and sandhill. We did not acquire this farm because it had a great potential for growing crops. Rather we were interested in the variety of ecologic and topographic types which, even within the confines of our property, represented a condensed version of many different types of land in the Wisconsin countryside. It has also a very peculiar esthetic and historical interest. Marquette's canoes slipped quietly past our favorite fishing hole on the river. Passenger pigeons had once roosted in our great oaks. The few remaining white pines silhouetted against the sky-glow of evening made one think of the Round River and the Blue Ox. All right, we had acquired this place. What were we to do with it. Its resources were narrowly limited and peculiar. They had little economic value. All the more reason that they should be appraised in order that they be fully utilized and appreciated. So, while we were hammering and sawing the old stable into a useable homestead, we walked, sat, dug, and pruned in every coulee and covert, in every thicket and thatch. By compass and pace we mapped the boundaries, the vegetation, and sketched in the topography with notes on the distribution of soil and the occurrence of water. We counted the various kinds of birds and found there was a reasonable population of woods species, mostly transients. There were no pheasant, no quail, practically no grouse, and in spring only an occasional woodcock. In conjunction with the analysis of what we had to work with we started immediately on the task of development. The techniques were chosen with an eye to specific goals. We wanted, over a long period of time, to grow a stand of conifers which would yield both pleasure to the eye and logs to the saw. We could see the possibilities of having quail, pheasants, grouse, and deer, and of extending the stay of some of the migrant species. So we set to work with shovel and axe, wire and nails, and a will to succeed. Trees were lopped so that they formed brush piles. Wild grapes were brought in and planted on the brush piles. Grass was removed with a shovel where it was competing with desirable wild flowers. Little patches of corn and beans were planted to provide proper combinations of food and cover. Within few years we had pheasants, grouse, and woodcock to shoot, wild flowers to delight the eye and the nose, and the annual increments on the stem of every pine were future increments of dollars in the bank. The problem of appraisal, development, and management are similar, whatever the nature of the resource. Resources may be renewable or nonrenewable. With renewable resources our problem is to increase, insofar as possible, the take from each increment. With nonrenewable resources the problem is to develop in an orderly manner without waste.

Circular↗
USGS1960

The conservation attitude

Forsaking his inheritance and its assurance of a comfortable existence, Guatama Buddha adopted the life of a pauper to seek the intellectual joys of pure contemplation. Under a mulberry tree, it is said, he propounded a 12-point program of ethical conduct stressing the development of a disinterested outlook in each individual. Temples, ritual, and idols he considered distractions from the basic need. He felt that there was a basic need for the development of an attitude. The Brahmins as well as the lower castes recognized the merits of the system suggested by Buddha, but they molded his teachings into an accessory to existing rituals and dogma. They soon forgot that Guatama wanted no idols and no temples. They forgot his admonition that an attitude was the thing that really counted. Despite his expressed wish, today Buddha in stone, in bronze, and in gold ponders these things in thousands of temples and hears the prayers of millions who still seek the truths of an ethical life. Today, conservation has its temples. The temples of conservation include hundreds of irrigation reservoirs; it has prayer-sticks in miles of contour plow furrows, and the Buddha of a drop-inlet structure looks down on a conservation pool in myriad detention dams. Conservation is well established today in the minds of the American public. It seems appropriate to analyze at this time just what it is that is established in the public mind. In what ways have we, too, substituted the temples, the ritual, and the idols for an attitude?

Circular↗
USGS1960

Ecological systems and the water resources

In ancient Sparta there were two principal classes of society, the citizen and the helot. The citizen was trained principally to be a warrior. The helot, a serf, was the tiller of the land but could be called to military duty. The history of Herodotus makes it amply clear that making war was the biggest business of the times. Because the Spartans were always marching off to war with someone, they found the landbound position of their city, located as its is in a small central basin nearly surrounded by mountains, somewhat of a disadvantage. When they were under attack, of course, this situation was a favorable one inasmuch as a seaborne enemy had to march inland to come to grips with the Lacedaemonians. The relatively small size of the independent states meant that the Spartans had no direct access through their own lands to the sea. There is evidence that the Spartans reached an agreement with surrounding states concerning a free corridor. There would be maintained by all the Grecian states of the Peloponnesus an access route stretching essentially from Sparta to Corinth, through which a marching army could have access to a seaport. As a secondary benefit, this no man's land, which in our western lingo might be called a stock driveway, allowed merchants and their caravans to move freely between the flourishing trading port of Corinth and the inland cities to the south and west. Apparently one portion of the agreement between the states with regard to the use of this access zone was that there should be no permanent agricultural or grazing in the driveway. As a result, through several centuries B.C. during which there was high population density in the Aegean area, one strip of land was exempted from the pressures of grazing, lumbering, and agriculture which characterized most of the rest of the landscape. Today this driveway maintains a forest cover. In contrast, mountainsides nearby with an even larger annual rainfall support hardly a tree. It is not entirely apparent why subsequent centuries did not see this area denuded. Even with the scanty details known to me it seems clear that the peculiar history of this one area potentially offers us a greater insight into some aspects of forest and land conditions of classical times than extant written records. The several references to sources of timber and cutting of forests contained in the vivid chronicle of Herodotus are valuable, but they lack species identification for the most part. Though rich in human understanding and psychological insight, his history strongly resembles the travel sagas of the Spanish Conquistadors of our Southwest, who had no real eye for "country." Even a careful reading of the works of early travelers such as Coronado, Garces, and Espejo, gives no picture of the nature of the country, its vegetation, or its rivers. To describe a biota there is no substitute for a sample. It is logical to ask what one might want to know which would require the preservation of a sample. Whether such a question is asked at all is a reflection on the stage of intellectual maturity of a civilization. We take for granted that there is social gain in the erection and maintenance of a museum of fine arts, a museum of natural history, or a historical museum. Sooner or later we should be mature enough to extend this concept to include a "museum" consisting of samples of land types as nearly as possible unaffected by man.

Circular↗
USGS1960

Flow resistance in sinuous or irregular channels

The resistance to fully developed turbulent flow at constant depth in an open channel increases as the square of the mean velocity as long as the boundary conditions remain completely unchanged. The presence of the free water surface allows the possibility of departure from the relationship of resistance to the square of the velocity. Experimental evidence is given, which is in quantitative agreement with fluid dynamic theory, that such departure may be abrupt, with a marked increase of resistance. These departures are observed under conditions of boundary and flow which occur commonly in natural rivers. It is shown that the condition under which this discontinuous increase in resistance occurs is definable by the mean Froude number for the whole flow which may be as small as 0.4. At this initial state, the rate of resistance increase with the square of the velocity may be more than double. The phenomenon, which is absent in straight uniform channels, is associated with excessive deformations of the free surface due to transverse deflections of the whole or a part of the flow by changes along the channel in the curvature of the flow boundary. In the simple cases examined the critical Froude number at which the sudden jump occurs depends mainly on the ratio of channel width to mean radius of channel curvature, though the inclination of the banks appears also to have a minor effect Over the range of values of the above ratio usually to be found in natural rivers, the critical Froude number ranges between 0.4 and 0.55. The possible significance is discussed of the remarkable correspondence between this range of critical Froude number and the range of Froude number within which river flow at bankfull stage appears to be restricted.

Professional Paper↗
USGS1960

Water and the Southwest

In a pluvial period associated with Wisconsin glaciation the closed basin of the Estancia valley in New Mexico held a lake which, at its maximum extent, was 150 feet deep and had a surface area of 450 square miles. This basin, with an elevation of about 6,000 feet, has at present an annual precipitation of about 16 inches. Estimates have been made of the Pleistocene precipitation necessary to maintain this pluvial lake. Instead of the present annual average of 14 inches, it has been variously estimated that the precipitation must have been 20 to 24 inches. Lakes existed during Pleistocene time in many places in Western United States which are now true deserts. There is evidence in many places in this area that early man lived on the shores of these lakes. He must have adapted himself to the increasing aridity. Some of the forms of this adaptation can be seen even at present in the form of flood-water farming practices highly developed by the Hopi Indians.

Landscape↗
USGS1959

Water resource development and management

In a sandy, riverside location in Wisconsin, my family has a farm, once abandoned by a previous owner because it would not produce much corn. By the time we bought it – for a pittance – only a few remnants of white pine remained from the magnificent stands made famous by the Paul Bunyan legend. In this part of Wisconsin the pines were, even originally, restricted only to patches of the better soil, and the variability of the glacial topography has resulted in an interesting mixture of prairie marsh, swamp woodlot, and sand hill. We did not acquire this farm because it had great potential for growing crops. Rather we were interested in the variety of ecologic and topographic types, which, even within the confines of our property, represented a condensed version of the many different types of land in the Wisconsin countryside. The farm also has a very peculiar aesthetic and historical interest. Marquette’s canoes once slipped quietly past our favorite fishing hole on the river; passenger pigeons once roosted in our great oaks; and the few remaining white pines silhouetted against the sky-glow of evening made one think of the Round River and the Blue Ox.

Journal of the American Water Works Association↗
USGS1959

Probability analysis applied to a water-supply problem

The literature on probability techniques applicable to problems in hydrology is abundant but scattered through scientific journals of both hydrology and statistics. Important administrative and judicial decisions presently face water-compact commissions, courts, and water-planning committees. These and other groups might find useful, a brief and simplified discussion of how statistical techniques can aid in analysing problems of water supply. The interest expressed in this subject by various parties to the litigation concerning the Colorado River prompts this publication of material, which was presented in August 1958 before the Special Master of the Supreme Court hearing the proceedings of Arizona v. California et al . The examples presented here are the same as those used in testimony before the Special Master, but there are included the basic computations, which were too detailed to present in the actual testimony. The specific example, which was analyzed in that testimony, was a 61-year series of annual discharge values of the Colorado River at Lees Ferry, 1896 to 1956, inclusive. However, the methodology presented herein is generally applicable to many other streamflow records; and the specific data discussed should be viewed as exemplifying the types of information, which can be obtained from any streamflow record.

Circular↗
USGS1959

Climatology and the problems of western grasslands

Sixty years after Coronado, Don Juan de Onate wrote the first reasonably good description of the High Plains. He was near the present site of Wichita, Kansas, in 1601, when he arrived a t a large rancheria, or temporary Indian camp, containing more than 5000 souls. Onate's account expressed wonderment at the great extent of the level land, a t the numerous small streams bordered with luxuriant groves of trees, and, of course, at the large number of buffalo. We shall never see the wonderland of the blossoming prairie which he described as follows: Grazing for the horses "had been lacking for several days, as there had been none for many leagues, for the fields there were covered with flowers of a thousand different kinds, so thick that they choked the pasture " (1, p. 256). We who fly from Chicago to Denver in a few hours cannot get the same view of the western grasslands as those who, with rifle or sword in hand, moved at the rate of 10 to 15 miles a day. The tall- and short-grass prairies of the West comprise more than 700,000 square miles in the United States alone, not to mention the great prong extending northward into Canada. Such an area represents nearly a quarter of the United States. There are areas other than prairie where grass is an important natural resource. Among these should be mentioned the grass openings in woodland and along the borders of desert shrub associations in the plateau and basin-and-range provinces. So considered, the western grassed areas constitute even a larger proportion of our country. This vast domain has problems commensurate in complexity with its geographic scope, and these are in part related to the changes which have occurred since settlement. I shall attempt to state the most important current problems as I see them, and then will discuss briefly the role of the climatologist in their solution.

Conference Paper↗
USGS1958

Water and the conservation movement

Every age has its unique touchstone, its hallmark. The Nineties were thought gay. The Twenties had jazz and John Held, Jr. The Thirties had breadlines, dust bowls, the forgotten man. And each recent period has been studded with so many flashy gems, both paste and genuine, that no hallmark would alone be enough to label it. Of the present age, one of the nameplates will carry the word "Conservation." The first time a museum visitor walks by that label he will probably stop, push back the plexiglas globe of his space helmet and say to himself, "I never thought that conservation was a keynote of the Fifties." But I imagine he might agree as the pathetic truth of that label dawned on his tired body, accustomed to canned entertainment, synthetic flavors, and fighting the afternoon traffic of the jet lanes. I can imagine him musing: "Conservation, the hallmark of the Fifties. Somebody about that time said about something or other, 'too little and too late.'"

Circular↗
USGS1957

River channel patterns: Braided, meandering, and straight

Channel pattern is used to describe the plan view of a reach of river as seen from an airplane, and includes meandering, braiding, or relatively straight channels. Natural channels characteristically exhibit alternating pools or deep reaches and riffles or shallow reaches, regardless of the type of pattern. The length of the pool or distance between riffles in a straight channel equals the straight line distance between successive points of inflection in the wave pattern of a meandering river of the same width. The points of inflection are also shallow points and correspond to riffles in the straight channel. This distance, which is half the wavelength of the meander, varies approximately as a linear function of channel width. In the data we analysed the meander wavelength, or twice the distance between successive riffles, is from 7 to 12 times the channel width. It is concluded that the mechanics which may lead to meandering operate in straight channels. River braiding is characterized by channel division around alluvial islands. The growth of an island begins as the deposition of a central bar which results from sorting and deposition of the coarser fractions of the load which locally cannot be transported. The bar grows downstream and in height by continued deposition on its surface, forcing the water into the flanking channels, which, to carry the flow, deepen and cut laterally into the original banks. Such deepening locally lowers the water surface and the central bar emerges as an island which becomes stabilized by vegetation. Braiding was observed in a small river in a laboratory. Measurements of the adjustments of velocity, depth, width, and slope associated with island development lead to the conclusion that braiding is one of the many patterns which can maintain quasi-equilibrium among discharge, load, and transporting ability. Braiding does not necessarily indicate an excess of total load. Channel cross section and pattern are ultimately controlled by the discharge and load provided by the drainage basin. It is important, therefore, to develop a picture of how the several variables involved in channel shape interact to result in observed channel characteristics. Such a rationale is summarized as follows: Channel width appears to be primarily a function of near-bankfull discharge, in conjunction with the inherent resistance of bed and bank to scour. Excessive width increases the shear on the bed at the expense of that on the bank and the reverse is true for very narrow widths. Because at high stages width adjustment can take place rapidly and with the evacuation or deposition of relatively small volumes of debris, achievement of a ,relatively stable width at high flow is a primary adjustment to which the further interadjustments between depth, velocity, slope, and roughness tend to accommodate. Channel roughness, to the extent that it is determined by particle size, is an independent factor related to the drainage basin rather than to the channel. Roughness in streams carrying fine material, however, is also a function of the dunes or other characteristics of bed configuration. Where roughness is independently determined as well as discharge and load, these studies indicate that a particular slope is associated with the roughness. At the width determined by the discharge, velocity and depth must be adjusted to satisfy quasi-equilibrium in accord with the particular slope. But if roughness also is variable, depending on the transitory configuration of the bed, then a number of combinations of velocity, depth, and slope will satisfy equilibrium. An increase in load at constant discharge, width, and caliber of load tends to be associated with an increasing slope if the roughness (dune or bed configuration) changes with the load. In the laboratory river an increase of load at constant discharge, width, and caliber resulted in progressive aggradation of long reaches of channel at constant slope. The adjustments of several variables tending toward the establishment of quasi-equilibrium in river channels lead to the different channel patterns observed in nature. For example, the data indicate that at a given discharge, meanders occur at smaller values of slope than do’ braids. Further, at the same slope braided channels are associated with higher bankfull discharges than are meanders. An additional example is provided by the division of discharge around islands in braided rivers which produces numerous small channels. The changes in slope, roughness, and channel shape which accompany this division are in accord with quasi-equilibrium adjustments observed in the comparison of large and small rivers.

Professional Paper↗
USGS1957

River flood plains: Some observations on their formation

On many small rivers and most great rivers, the flood plain consists of channel and overbank deposits. The proportion of the latter is generally very small. Frequency studies indicate that the flood plains of many streams of different sizes flowing in diverse physiographic and climatic regions are subject to flooding about once a year. The uniform frequency of flooding of the flood-plain surface and the small amount of deposition observed in great floods (average 0.07 foot) support the conclusion that overbank deposition contributes only a minor part of the material constituting the flood plain. The relatively high velocities (1 to 4 fps) which can occur in overbank flows and the reduction in sediment concentration which often accompanies large floods may also help account for this. Although lateral migration of channels is important in controlling the elevation of the flood plain, rates of migration are extremely variable and alone cannot account for the uniform relation the flood-plain surface bears to the channel. Detailed studies of flood plains in Maryland and in North Carolina indicate that it is difficult to differentiate between channel and overbank deposits in a stratigraphic section alone. Because deposition on the flood plain does not continue indefinitely, the flood-plain surface can only be transformed into a terrace surface by some tectonic or climatic change which alters the regimen of the river and causes it to entrench itself below its established bed and associated flood plain. A terrace, then, is distinguished from a flood plain by the frequency with which each is overflowed.

Professional Paper↗
USGS1957

Water problems in the present trend towards greater aridity

In the past few days we have heard a number of scientists, gathered here at Scripps Institution of Oceanography, discuss research work which, in one manner or another, bears on problems related to water resources. They have been discussing, particularly, problems in the field of climatology, and have speculated on the meaning of the results of this research. One of the problems under discussion was the nature, and possible cause, of the climatic fluctuation which we have experienced in recent decades, and its relation to climatic changes in recent geologic time since the last glaciation. These discussions have given me the courage, or perhaps the recklessness, to indulge in some speculation relative to various aspects of water resource problems in the United States.

Conference Paper↗
USGS1956

Ephemeral streams - Hydraulic factors and their relation to the drainage net

The hydraulic factors of width, depth, velocity, and suspended sediment load of ephemeral streams near Santa Fe, N. Mex., were measured during flood flow. Later, channel slope was measured. These flood-flow data, in conjunction with an analysis of drainage-basin configuration by the methods proposed by Horton, are used to determine the generalized interrelation of stream order and hydraulic variables. The method developed for determining this interrelation allows an integration of the geographic and physiographic characteristics of a drainage basin with the channel characteristics; specifically, the interrelation of the length, number, and drainage area of streams of various sizes with their respective discharge, width, depth, velocity, slope, channel roughness, and suspended-sediment load.

New Mexico↗
USGS1956

Floods in relation to the river channel

Among the rivers studied by us two broad types may be distinguished. Channels in the semi-arid areas scour at high discharges so that the bed lowers nearly as much as the water surface rises. Detailed data on the middle reaches of the Rio Grande in New Mexico during the spring floods of 1948 and 1952 indicate that the bed aggrades to nearly its pre-flood level as the flood recedes. Channel banks may move rapidly by undercutting during periods of scour and levees are liable to failure not from overtopping but by undercutting. In Connecticut, a sub-humid area, the repetitive processes of scour and fill in the semi-arid region were not demonstrated by the great floods of 1955. In a few reaches fresh sand was deposited over gravel beds subsequently to be removed by lower flows. Boulders four to six feet in diameter were moved in places over undisturbed beds of one-inch gravel. Channel widening occurred primarily in rivers in narrow valleys which confined the flow within the channel. Scour and deposition on flood plains adjacent to the rivers was irregular. Most deposits could be traced to local sources. In general, flood waters modified but did not vastly alter the prevailing configuration of the channel and structure of the flood plain.

Proceedings of the International Association of Hy↗
USGS1956

Land use and sediment yield

When the vegetal cover is removed from a land surface, the rate of removal of the soil material, at least initially, increases rapidly. So well known is this principle that it hardly needs restatement. If attention is focused on any individual drainage basin in its natural state, large or small, and inquiry is made as to the rate of denudation, a quantitative answer is not easily obtained. The possible error in any computation of rate of sediment production from any given drainage basin is considerable. Significant variations are found in sediment yields from closely adjacent watersheds which appear to be generally similar. To make a quantitative evaluation of the change in the rate of denudation when the natural vegetation is disturbed is, therefore, even more difficult. Considering the fact that "soil conservation" has been promoted to the status of a science, our lack of ability to answer what is apparently so simple a question may seem surprising. Let us look at some of the reasons.

Conference Paper↗
USGS1955

Flood control problems

Throughout the world, alluvial soils are among the most fertile and easiest cultivated. Alluvial valleys are routes for transportation either by water or by road and railroad. Rivers are sources of water, a necessity of life. But these river valleys and alluvial deposits, which have so many desirable characteristics and which have increased so greatly in population, are periodically occupied by the river in performing its task of removing the excess of precipitation from the land area and carrying away the products of erosion. How a river behaves and how the river flood plain appears depend on the relationships between water and sediment combined with the existing topography. Thus rivers and their alluvial deposits provide an endless variety of forms which are shaped, to a large extent, by the river flow during periods of rapid removal of debris and of excessive rainfall. The mechanics of river formation are such, however, that the highest discharges are not contained within a limited channel. How much water a channel will carry depends upon the frequency of occurrence of a flow. Low flows, which occur very frequently, are not important in channel formation. Neither are the infrequent discharges of very great magnitude which, although powerful, do not occur often enough to shape the channel. Channel characteristics, are dependent on those discharges of moderate size which combine power with frequency of occurrence to modify the channel from. In the highest discharges of a stream, water rises above the confines of its banks and flows over the flood plain. It must be considered, therefore, that floods are natural phenomena which are characteristic of all rivers. They perform a vital function in the maintenance of river forms and out of bank flow may be expected with a reasonable degree of regularity.

Journal of Soil and Water Conservation in India↗
USGS1954

Studies of river morphology

A number of generalizations concerning the behavior and natural characteristics of river channels have been developed by the U.S. Geological Survey in several recently completed studies of river morphology. Measurements of parameters such as the discharge, suspended load, bed material, velocity of flow, channel slope, and channel shape indicate that many river channels are characterized by an orderly, progressive change of these variables from their headwaters to their mouths. The interaction of the variables and the establishment of a stable channel suggest that the morphology of the stream is controlled by a kind of equilibrium.

Science↗
USGS1954

A postglacial chronology for some alluvial valleys in Wyoming

Alluvial terraces were studied in several major river basins in eastern Wyoming. Three terraces are present along nearly all the streams and large tributaries. There are several extensive dissected erosion surfaces in the area, but these are much older than, and stand well above, the recent alluvial terraces with which this report is concerned. The three alluvial terraces stand respectively about 40, 10, and 5 feet above the present streams. The uppermost and oldest is a fill terrace comprised of three stratigraphic units of varying age. The oldest unit is Pleistocene and the youngest unit postdates the development of a soil zone, or paleosol, which is characterized by strong accumulation of calcium carbonate and gypsum. This paleosol is an important stratigraphic marker. The middle terrace is generally a cut terrace and is developed on the material making up the youngest alluvium of the high terrace. The lowest is a fill terrace, the surface of which is only slightly higher than the present flood plain. The oldest terrace can tentatively be traced into mountain valleys of the Bighorn Range on the basis of discontinuous remnants. The terrace remnants occur far upstream from the youngest moraine in the valleys studied. On this basis, the terrace sequence is considered to postdate the last Wisconsin ice in the Bighorn Mountains. The paleosol is tentatively correlated with Altithermal time, called in Europe the Climatic Optimum. The terrace sequence is very similar to that suggested by various workers in the southwestern United States. Two streams, Clear Creek and the Powder River, deposited comparable silty alluvium, the surface of which now comprises the highest alluvial terrace. The gradients of these former flood plains differed markedly between the two streams despite the comparability in size of material deposited. This difference in gradient is believed to have required different relative contributions of water from mountain and plain areas than now exist. Knowledge of Recent physiographic history of the area is the basis of determining the relative ages of some gully features. Certain vertical-walled channels or arroyos that might appear to be attributable to postsettlement grazing or other man-induced influences are shown to be Recent but pre-Columbian in age. Such differentiation in age of erosion features is necessary for proper understanding of present-day soil erosion problems.

Wyoming↗