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1.
The supraregional GIS-supported stochastical model, WEKU, for the determination of groundwater residence times in the upper
aquifers of large groundwater provinces is presented. Using a two-dimensional analytical model of groundwater flow, groundwater
residence times are determined within two extreme cases. In the first case, maximal groundwater residence times are calculated,
representing the part of groundwater, that is drained by the main surface water of a groundwater catchment area. In the second
case, minimal groundwater residence times for drainage into the nearest surface water are determined. Using explicit distribution
functions of the input parameters, mean values as well as potential ranges of variations of the groundwater residence times
are derived. The WEKU model has been used for the determination of groundwater residence times throughout Germany. The model
results – mean values and deviations of the groundwater velocity and the maximal and minimal groundwater residence times in
the upper aquifers – are presented by general maps and discussed in detail. It is shown that the groundwater residence times
in the upper aquifer vary regionally, differentiated between less than 1 year and more than 2000 years. Using this information,
the time scales can be specified, until measures to remediate polluted groundwater resources may lead to a substantial groundwater
quality improvement in the different groundwater provinces of Germany. With respect to its supraregional scale of application,
the WEKU model may serve as a useful tool for the supraregional groundwater management on a state, federal or international
level.
Received: 15 August 1995 · Accepted: 15 October 1995 相似文献
2.
Climate-Years in the True Prairie: Temporal Fluctuations of Ecologically Critical Climate Conditions
The True Prairie (TP) is a large area in the central U.S. which was a tall grass prairie for thousands of years prior to its conversion to crop land. An analysis of climatically controlling factors indicated that the tall grass prairie is favored by the ratio of warm season precipitation to potential evapotranspiration exceeding 0.75 (west boundary), cold season precipitation less than 38 cm (south boundary), high cold-season frequency of thunderstorms (north boundary), and high drought frequencies (entire region). A `climate-year' approach was used to assess the temporal and spatial variability of these conditions during the 20thcentury. This analysis did not reveal any long-term trends in most climate-year types, although there were significant decadal-scale fluctuations, most notably a high frequency of drought-type years in the 1930s and 1950s. However, the well-documented upward trend in precipitation is manifested in an increasing frequency of one climate-year type characterized by above normal cold season precipitation in the southern border area of the TP. 相似文献
3.
C
T
2measurements taken over a desert in stable conditions indicate that the atmosphere remains intermittently turbulent for Ri numbers as high as 10. This is in contrast to previous results which suggest that the atmosphere is essentially nonturbulent for Ri > 2. These measurements also indicate that time-averaged C
T
2measurements do not scale with the time-averaged mean Ri number in very stable conditions. However, the standard deviation of log10
C
T
2does appear to scale with Ri. 相似文献
4.
G. Kunkel 《Geoforum》1971,2(4):76
5.
This paper presents the findings of a collaborative research project of the Geological Survey of Lower Saxony (NLfB) and the Programme Group Systems Analysis and Technology Evaluation (STE) of Research Centre Jülich on the GIS-based determination of the mean long-term groundwater recharge in Lower Saxony using high-resolution digital data (Dörhöfer and others 2001). The model calculations were performed on the basis of the water-balance model GROWA (Kunkel and Wendland 2002) with a spatial resolution of 100x100 m2. The accuracy of the calculated groundwater recharge values for the period 1961–1990 was verified on the basis of data from gauging stations and displayed a good agreement between observed runoff values and model results. 相似文献
6.
7.
G. Kunkel 《GeoJournal》1981,5(2):171-178
The Human population suffers from a serious and paradoxical misunderstanding of its own place and importance within Nature:
Unable or unwilling to control its own growth, being faced by overcrowding with resulting loss of productive land, and lack
of food both in quantity and quality, alternative ways of feeding Mankind and his domestic stock have to be found. In the
present paper examples and suggestions are given to illustrate how weeds—the generally considered “useless” elements of the
Plant Kingdom—could become accepted as alternative food-providers.
Thirty spokes share the wheel's hub; It is the center hole that makes it useful. Shape clay into a vessel; It is the space
within that makes it useful. Cut doors and windows for a room; It is the holes which make it useful. Therefore profit comes
from what is there; Usefulness from what it not there. LAO TSU, in Tao te Ching 相似文献
8.
Transposed Climates for Study of Water Supply Variability on the Laurentian Great Lakes 总被引：2，自引：0，他引：2
Kenneth E. Kunkel Stanley A. Changnon Thomas E. Croley II Frank H. Quinn 《Climatic change》1998,38(4):387-404
Hydrological models of the Great Lakes basin were used to study the sensitivity of Great Lakes water supplies to climate warming by driving them with meteorological data from four U.S. climate zones that were transposed to the basin. Widely different existing climates were selected for transposition in order to identify thresholds of change where major impacts on water supplies begin to occur and whether there are non-linear responses in the system. The climate zones each consist of 43 years of daily temperature and precipitation data for 1,000 or more stations and daily evaporation-related variables (temperature, wind speed, humidity, cloud cover) for approximately 20–35 stations. A key characteristic of these selected climates was much larger variability in inter-annual precipitation than currently experienced over the Great Lakes. Climate data were adjusted to simulate lake effects; however, a comparison of hydrologic results with and without lake effects showed that there was only minor effects on water supplies. 相似文献
9.
10.
Assessment of groundwater residence times in the pore aquifers of the River Elbe Basin 总被引：1，自引：0，他引：1
An area covering assessment of the groundwater residence times for the upper pore aquifers in the River Elbe Basin was performed. Residence times were determined by combining groundwater velocities and flow distances along each flow-path to the surface waters using a two-dimensional model approach. Groundwater velocity was calculated as a function of hydraulic conductivity, hydraulic gradient and effective yield of pore space. Flow paths were obtained by an analysis of the morphology of the groundwater table. The mean groundwater residence time in the pore aquifers of the River Elbe Basin was quantified to about 25 years. A strong temporal blurring in the different regions between less than one year and more than 250 years was obtained. For the regional groundwater management in the Elbe Basin the groundwater residence times are an important parameter, which helps to take into account the temporal dimension in the assessment of the impact of political measures aiming at the improvement of groundwater quality with regard to diffuse pollutants (e.g. nitrate). 相似文献