Mapping irrigation potential from renewable groundwater in Africa - a quantitative hydrological approach

被引:50
作者
Altchenko, Y. [1 ,2 ,3 ]
Villholth, K. G. [1 ]
机构
[1] Int Water Management Inst, Pretoria, South Africa
[2] Minist Agr Agroalimentaire & Foret, Paris, France
[3] Univ Paris 06, CNRS, Lab METIS, UMR UPMC 7619, Paris, France
关键词
SUB-SAHARAN AFRICA;
D O I
10.5194/hess-19-1055-2015
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
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 x 10(6) 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 degrees 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 in homogeneously 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 km(3) depending on scenario. The total area of cropland irrigable with renewable groundwater ranges from 44.6 to 105.3 x 10(6) ha, corresponding to 20.5 to 48.6% of the cropland over the continent. In particular, significant potential exists in the semiarid 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.
引用
收藏
页码:1055 / 1067
页数:13
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