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  • 1
    Electronic Resource
    Electronic Resource
    THE CONCEPT OF HYDROLOGIC LANDSCAPES (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 37 (2001), S. 0 
    Details
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : Hydrologic landscapes are multiples or variations of fundamental hydrologic landscape units. A fundamental hydrologic landscape unit is defined on the basis of land-surface form, geology, and climate. The basic land-surface form of a fundamental hydrologic landscape unit is an upland separated from a lowland by an intervening steeper slope. Fundamental hydrologic landscape units have a complete hydrologic system consisting of surface runoff, ground-water flow, and interaction with atmospheric water. By describing actual landscapes in terms of land-surface slope, hydraulic properties of soils and geologic framework, and the difference between precipitation and evapotranspiration, the hydrologic system of actual landscapes can be conceptualized in a uniform way. This conceptual framework can then be the foundation for design of studies and data networks, syntheses of information on local to national scales, and comparison of process research across small study units in a variety of settings. The Crow Wing River watershed in central Minnesota is used as an example of evaluating stream discharge in the context of hydrologic landscapes. Lake-research watersheds in Wisconsin, Minnesota, North Dakota, and Nebraska are used as an example of using the hydrologic-land-scapes concept to evaluate the effect of ground water on the degree of mineralization and major-ion chemistry of lakes that lie within ground-water flow systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1752-1688.2001.tb00973.x
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  • 2
    Electronic Resource
    Electronic Resource
    UNCERTAINTIES IN ESTIMATING THE WATER BALANCE OF LAKES (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 17 (1981), S. 0 
    Details
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : Evaluation of hydrologic methodology used in a number of water balance studies of lakes in the United States shows that most of these studies calculate one or more terms of the budget as the residual. A literature review was made of studies in which the primary purpose was error analysis of hydrologic measurement and interpretation. Estimates of precipitation can have a wide range of error, depending on the gage placement, gage spacing, and areal averaging technique. Errors in measurement of individual storms can be as high as 75 percent. Errors in short term averages are commonly in the 15-30 percent range, but decrease to about 5 percent or less for annual estimates. Errors in estimates of evaporation can also vary widely depending on instrumentation and methodology. The energy budget is the most accurate method of calculating evaporation; errors are in the 10–15 percent range. If pans are used that are located a distance from the lake of interest, errors can be considerable. Annual pan-to-lake coefficients should not be used for monthly estimates of evaporation because they differ from the commonly used coefficient of 0.7 by more than 100 percent. Errors in estimates of stream discharge are often considered to be within 5 percent. If the measuring section, type of flow profile, and other considerations, such as stage discharge relationship, are less than ideal errors in estimates of stream discharge can be considerably greater than 5 percent. Errors in estimating overland (nonchannelized) flow have not been evaluated, and in most lake studies this component is not mentioned. Comparison of several lake water balances in which the risdual consists solely of errors in measurement, shows that such a residual, if interpreted as ground water, can differ from an independent estimate of ground water by more than 100 percent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1752-1688.1981.tb02593.x
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  • 3
    Electronic Resource
    Electronic Resource
    Simulations of Flow in Crystalline Rock and Recharge from Overlying Glacial Deposits in a Hypothetical New England Setting (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 33 (1995), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Cross-sectional, finite-difference, steady-state ground-water-flow models of a generalized New England landscape were constructed to examine the effects of hydraulic conductivity and topography on bulk-fluid flow processes in fractured crystalline rock. The generalized landscape consists of a flat hilltop, a hillside that has a slope of 0.17 ft/ft, and a flat river valley. It includes three hydrogeologic units, stratified drift in the river valley, glacial till, and underlying crystalline rock.Distribution of recharge to and discharge from bedrock is affected by the presence of small topographic features, such as terraces on the hillside. Most of these terraces consist partly or entirely of sand, and they create localized areas of recharge to and discharge from bedrock. Maximum recharge to bedrock commonly occurs at downward inflections of the water table, and discharge occurs at upward inflections of the water table. These inflections of the water table are associated with inflections in topography because the shallow depth of water on hilltops and hillsides resemble the configuration of the land surface.Regional ground-water flow in crystalline rock and distribution of bedrock recharge and discharge are also affected by heterogeneities in hydraulic conductivity of the bedrock. Vertical heterogeneity creates short, shallow flow paths in high-relief terrain. Horizontal heterogeneity causes large variations in the size of bedrock recharge areas; in some cases the difference from homogeneous conditions is more than 50 percent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1995.tb00041.x
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  • 4
    Electronic Resource
    Electronic Resource
    The Significance of Ground Water to the Accumulation of Iron and Manganese in the Sediments of Two Hydrologically Distinct Lakes in North-Central Minnesota: A Geological Perspective (2003)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 41 (2003), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Williams and Shingobee lakes are at opposite ends of the local ground water flow system in the Shingobee River Headwaters Area (SRHA) in north-central Minnesota. Williams Lake, situated near the highest point in the flow system, has no surface inlet or outlet, and ground water and precipitation are the only sources of water. Shingobee Lake, situated at the lowest point in the flow system, has the Shingobee River as an inlet and outlet. Ground water directly contributes an estimated one-fourth of the water input to Shingobee Lake. The Shingobee River also receives large amounts of ground water discharge along its reach to Shingobee Lake providing a large, indirect source of ground water to the lake. Differences in nutrient concentrations reflect the residence times and nutrient supplies of these two lakes. The average phosphorus content of Shingobee Lake is about twice that of Williams Lake. Consequently, phy-toplankton productivity in Shingobee Lake is much higher than in Williams Lake, leading to an oxygen-deficient (〈1 ppm dissolved oxygen) hypolimnion within a month after overturn in both the spring and fall. Because of the extreme reducing conditions in the hypolimnion of Shingobee Lake, high concentrations of dissolved iron and manganese are present there during summer stratification. In some years, the manganese concentration in the hypolimnion of Shingobee Lake remains high throughout the year. Precipitation of iron and manganese minerals, presumed to be X-ray amorphous oxyhydroxides, at periods of fall and spring overturn result in concentrations of iron and manganese in surface sediments of Shingobee Lake that are seven times and 27 times higher, respectively, than can be explained by contributions of iron and manganese from detrital aluminosilicates. These findings indicate that the source and amounts of this excess iron and manganese found in the sediments are correlated to the amount of iron- and manganese-rich ground water discharging to Shingobee Lake. Because iron and manganese oxyhydroxides are efficient adsorbers of phosphorus, concentrations of phosphorus are also high in the sediments of Shingobee Lake. Without this sequestration of phosphorus, the productivity of Shingobee Lake would probably be much higher.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.2003.tb02437.x
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  • 5
    Electronic Resource
    Electronic Resource
    Where Does the Ground Water in Small Watersheds Come From? (2003)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 41 (2003), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Surface water and ground water watersheds commonly do not coincide. This condition is particularly relevant to understanding biogeochemical processes in small watersheds, where detailed accounting of water and solute fluxes commonly are done. Ground water watersheds are not as easily defined as surface watersheds because (1) they are not observable from land surface; (2) ground water flow systems of different magnitude can be superimposed on one another; and (3) ground water divides may move in response to dynamic recharge and discharge conditions. Field studies of relatively permeable terrain in Wisconsin, Minnesota, and Nebraska indicate that lakes and wetlands in small watersheds located near the lower end of extensive ground water flow systems receive ground water inflow from shallow flow systems that extend far beyond their surface watershed, and they may also receive ground water inflow from deeper regional flow systems that pass at depth beneath local flow systems. Field studies of mountainous terrain that have low-permeability deposits in New Hampshire and Costa Rica also indicate that surface water bodies receive ground water inflow from sources beyond their local surface watersheds. Field studies of lakes and wetlands in North Dakota, Nebraska, and Germany indicate that ground water divides move in response to changing climate conditions, resulting in a variable source of ground water inflow to those surface water bodies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.2003.tb02440.x
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  • 6
    Electronic Resource
    Electronic Resource
    Estimating Ground-Water Recharge from Streamflow Hydrographs for a Small Mountain Watershed in a Temperate Humid Climate, New Hampshire, USA (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Hydrographs of stream discharge were analyzed to determine ground-water recharge for two small basins draining into Mirror Lake, New Hampshire. Two methods of hydrograph analysis developed for determining ground-water recharge were evaluated, the instantaneous recharge method and the constant recharge method. For the instantaneous recharge method, recharge is assumed to be instantaneous and uniform over the basin. For the constant recharge method, recharge is assumed to be constant and uniform over the basin for a period of weeks to months. Both methods require that a ground-water recession slope be determined. The recession slope is used directly in the calculation for the instantaneous recharge method, and it is used as a base of reference for fitting a type curve in the constant recharge method. Results of the study indicated that the estimates of ground-water recharge for both methods agree to within about 10 percent. Two approaches to the instantaneous recharge method, manual and automated, were also evaluated, and the results were statistically similar.The baseflow component of streamflow commonly is assumed to be equivalent to ground-water recharge; therefore, two methods developed for determining the baseflow component of streamflow, graphical partitioning and digital filtering, were evaluated also. Baseflow values determined by graphical partitioning of hydrographs were about 25 percent less than the ground-water recharge values. Baseflow values determined by two different approaches to the mathematical digital filtering method were generally less than baseflow determined by graphical partitioning. However, one of the approaches to digital filtering agreed reasonably well with graphical partitioning if an appropriate filter constant was used. The other approach to digital filtering resulted in baseflow values that were much less than the other baseflow values and was therefore deemed inappropriate for use on these small mountain watersheds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00086.x
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  • 7
    Electronic Resource
    Electronic Resource
    THE VULNERABILITY OF WETLANDS TO CLIMATE CHANGE: A HYDROLOGIC LANDSCAPE PERSPECTIVE (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 36 (2000), S. 0 
    Details
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : The vulnerability of wetlands to changes in climate depends on their position within hydrologic landscapes. Hydrologic landscapes are defined by the flow characteristics of ground water and surface water and by the interaction of atmospheric water, surface water, and ground water for any given locality or region. Six general hydrologic landscapes are defined; mountainous, plateau and high plain, broad basins of interior drainage, riverine, flat coastal, and hummocky glacial and dune. Assessment of these landscapes indicate that the vulnerability of all wetlands to climate change fall between two extremes: those dependent primarily on precipitation for their water supply are highly vulnerable, and those dependent primarily on discharge from regional ground water flow systems are the least vulnerable, because of the great buffering capacity of large ground water flow systems to climate change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1752-1688.2000.tb04269.x
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  • 8
    Electronic Resource
    Electronic Resource
    Hepatic, pulmonary, and CNS involvement by histiocytosis X in an adult: MRI and CT appearance (1993)
    Springer
    European radiology 3 (1993), S. 91-93 
    Details
    ISSN: 1432-1084
    Keywords: Eosinophilic granuloma ; Histiocytosis X ; Liver Diseases ; magnetic Resonance Imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Histiocytosis X (HX) is a disease of the lymphoreticular system characterized by histiocytic infiltration of one or more tissues. We present a case with extensive hepatic involvement in an adult visualized on ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI). The findings on MRI are strongly suggestive of the correct diagnosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173533
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  • 9
    Electronic Resource
    Electronic Resource
    A conceptual framework for assessing cumulative impacts on the hydrology of nontidal wetlands (1988)
    Springer
    Environmental management 12 (1988), S. 605-620 
    Details
    ISSN: 1432-1009
    Keywords: Wetland hydrology ; Groundwater and surface water interrelationships ; Evapotranspiration ; Surface runoff ; Groundwater movement ; Drainage ; Reservoirs ; Lakes ; Geologic boundaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Wetlands occur in geologic and hydrologic settings that enhance the accumulation or retention of water. Regional slope, local relief, and permeability of the land surface are major controls on the formation of wetlands by surface-water sources. However, these landscape features also have significant control over groundwater flow systems, which commonly play a role in the formation of wetlands. Because the hydrologic system is a continuum, any modification of one component will have an effect on contiguous components. Disturbances commonly affecting the hydrologic system as it relates to wetlands include weather modification, alteration of plant communities, storage of surface water, road construction, drainage of surface water and soil water, alteration of groundwater recharge and discharge areas, and pumping of groundwater. Assessments of the cumulative effects of one or more of these disturbances on the hydrologic system as related to wetlands must take into account uncertainty in the measurements and in the assumptions that are made in hydrologic studies. For example, it may be appropriate to assume that regional groundwater flow systems are recharged in uplands and discharged in lowlands. However, a similar assumption commonly does not apply on a local scale, because of the spatial and temporal dynamics of groundwater recharge. Lack of appreciation of such hydrologic factors can lead to misunderstanding of the hydrologic function of wetlands within various parts of the landscape and mismanagement of wetland ecosystems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01867539
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  • 10
    Electronic Resource
    Electronic Resource
    Hydrology of Prairie Pothole Wetlands during Drought and Deluge: A 17-Year Study of the Cottonwood Lake Wetland Complex in North Dakota in the Perspective of Longer Term Measured and Proxy Hydrological Records (1998)
    Springer
    Climatic change 40 (1998), S. 189-209 
    Details
    ISSN: 1573-1480
    Keywords: wetland hydrology ; Palmer Drought Severity Index ; Devils Lake ; Pembina River
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract From 1988 to 1992 the north-central plains of North America had a drought that was followed by a wet period that continues to the present (1997). Data on the hydrology of the Cottonwood Lake area (CWLA) collected for nearly 10 years before, and during, the recent dry and wet periods indicate that some prairie pothole wetlands served only a recharge function under all climate conditions. Transpiration from groundwater around the perimeter of groundwater discharge wetlands drew water from the wetlands by the end of summer, even during very wet years. Long-term records of a climate index (Palmer Drought Severity Index), stream discharge (Pembina River), and lake level (Devils Lake) were used to put the 17-year CWLA record into a longer term perspective. In addition, proxy records of climate determined from fossils in the sediments of Devils Lake were also used. These data indicate that the drought of 1988-92 may have been the second worst of the 20th century, but that droughts of that magnitude, and worse, were common during the past 500 years. In contrast, the present wet period may be the wettest it has been during the past 130 years, or possibly the past 500 years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005448416571
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