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| Titel |
Mapping irrigation potential from renewable groundwater in Africa – a quantitative hydrological approach |
| VerfasserIn |
Y. Altchenko, K. G. Villholth |
| 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 ; 19, no. 2 ; Nr. 19, no. 2 (2015-02-26), S.1055-1067 |
| Datensatznummer |
250120638
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| Publikation (Nr.) |
 copernicus.org/hess-19-1055-2015.pdf |
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| Zusammenfassung |
| Groundwater provides an important buffer to climate variability in Africa.
Yet, groundwater irrigation contributes only a relatively small share of
cultivated land, approximately 1% (about 2 × 106 hectares)
as compared to 14% in Asia. While groundwater is over-exploited for
irrigation in many parts in Asia, previous assessments indicate an
underutilized potential in parts of Africa. As opposed to previous
country-based estimates, this paper derives a continent-wide, distributed
(0.5° spatial resolution) map of groundwater irrigation potential,
indicated in terms of fractions of cropland potentially irrigable with
renewable groundwater. The method builds on an annual groundwater balance
approach using 41 years of hydrological data, allocating only that fraction
of groundwater recharge that is in excess after satisfying other present
human needs and environmental requirements, while disregarding
socio-economic and physical constraints in access to the resource. Due to
high uncertainty of groundwater environmental needs, three scenarios,
leaving 30, 50 and 70% of recharge for the environment, were implemented.
Current dominating crops and cropping rotations and associated irrigation
requirements in a zonal approach were applied in order to convert recharge
excess to potential irrigated cropland. Results show an inhomogeneously
distributed groundwater irrigation potential across the continent, even
within individual countries, mainly reflecting recharge patterns and
presence or absence of cultivated cropland. Results further show that
average annual renewable groundwater availability for irrigation ranges from 692 to
1644 km3 depending on scenario. The total area of cropland irrigable
with renewable groundwater ranges from 44.6 to 105.3 × 106 ha,
corresponding to 20.5 to 48.6% of the cropland over the continent. In
particular, significant potential exists in the semi-arid Sahel and eastern
African regions which could support poverty alleviation if developed
sustainably and equitably. The map is a first assessment that needs to be complimented
with assessment of other factors, e.g. hydrogeological conditions,
groundwater accessibility, soils, and socio-economic factors as well as more
local assessments. |
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