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| Titel |
Global-scale modeling of groundwater recharge |
| VerfasserIn |
P. Döll, K. Fiedler |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 12, no. 3 ; Nr. 12, no. 3 (2008-05-29), S.863-885 |
| Datensatznummer |
250010662
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| Publikation (Nr.) |
 copernicus.org/hess-12-863-2008.pdf |
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| Zusammenfassung |
| Long-term average groundwater recharge, which is equivalent to renewable
groundwater resources, is the major limiting factor for the sustainable use
of groundwater. Compared to surface water resources, groundwater resources
are more protected from pollution, and their use is less restricted by
seasonal and inter-annual flow variations. To support water management in a
globalized world, it is necessary to estimate groundwater recharge at the
global scale. Here, we present a best estimate of global-scale long-term
average diffuse groundwater recharge (i.e. renewable groundwater resources)
that has been calculated by the most recent version of the WaterGAP Global
Hydrology Model WGHM (spatial resolution of 0.5° by 0.5°, daily time
steps). The estimate was obtained using two state-of-the-art global data
sets of gridded observed precipitation that we corrected for measurement
errors, which also allowed to quantify the uncertainty due to these equally
uncertain data sets. The standard WGHM groundwater recharge algorithm was
modified for semi-arid and arid regions, based on independent estimates of
diffuse groundwater recharge, which lead to an unbiased estimation of
groundwater recharge in these regions. WGHM was tuned against observed
long-term average river discharge at 1235 gauging stations by adjusting,
individually for each basin, the partitioning of precipitation into
evapotranspiration and total runoff. We estimate that global groundwater
recharge was 12 666 km3/yr for the climate normal 1961–1990, i.e. 32%
of total renewable water resources. In semi-arid and arid regions,
mountainous regions, permafrost regions and in the Asian Monsoon region,
groundwater recharge accounts for a lower fraction of total runoff, which
makes these regions particularly vulnerable to seasonal and inter-annual
precipitation variability and water pollution. Average per-capita renewable
groundwater resources of countries vary between 8 m3/(capita yr)
for Egypt to more than 1 million m3/(capita yr) for the Falkland
Islands, the global average in the year 2000 being
2091 m3/(capita yr). Regarding the uncertainty of estimated
groundwater resources due to the two precipitation data sets, deviation
from the mean is 1.1% for the global value, and less than 1% for 50 out of the 165 countries considered,
between 1 and 5% for 62, between 5 and 20% for 43 and between 20 and
80% for 10 countries. Deviations at the grid scale can be much larger,
ranging between 0 and 186 mm/yr. |
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