Knowledge of other factors such as crops grown, agro- ecological zone type, and distribution of farm size would be relevant to its interpretation. Other aspects of irrigation, including equity, efficiency, and importance to the overall national agricultural production are not reflected in the indicator. The indicator does not provide a measure of lands with irrigation potential. At the sub-national level, irrigated area as a percent of irrigable area can be a better indicator of both development potential and sustainable development. Supplementary data on drained area, the area equipped with sub-surface or open drains, and the residual area, can be useful for the interpretation of sustainability.
Data are also available from national sources in some countries only.
The data are estimated by countries at various periods and are then interpolated. Irrigation in Africa in Figures.