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Grid-cell-based crop water accounting for the famine early warning system

January 1, 2002

Rainfall monitoring is a regular activity of food security analysts for sub-Saharan Africa due to the potentially disastrous impact of drought. Crop water accounting schemes are used to track rainfall timing and amounts relative to phenological requirements, to infer water limitation impacts on yield. Unfortunately, many rain gauge reports are available only after significant delays, and the gauge locations leave large gaps in coverage. As an alternative, a grid-cell-based formulation for the water requirement satisfaction index (WRSI) was tested for maize in Southern Africa. Grids of input variables were obtained from remote sensing estimates of rainfall, meteorological models, and digital soil maps. The spatial WRSI was computed for the 1996–97 and 1997–98 growing seasons. Maize yields were estimated by regression and compared with a limited number of reports from the field for the 1996–97 season in Zimbabwe. Agreement at a useful level (r = 0·80) was observed. This is comparable to results from traditional analysis with station data. The findings demonstrate the complementary role that remote sensing, modelling, and geospatial analysis can play in an era when field data collection in sub-Saharan Africa is suffering an unfortunate decline.

Publication Year 2002
Title Grid-cell-based crop water accounting for the famine early warning system
DOI 10.1002/hyp.1025
Authors J. Verdin, R. Klaver
Publication Type Article
Publication Subtype Journal Article
Series Title Hydrological Processes
Index ID 70024486
Record Source USGS Publications Warehouse
USGS Organization Earth Resources Observation and Science (EROS) Center