MAPPR map showing irrigated cropland areas in Sudan (source).
Without a spatially-explicit picture of the distribution of farmland, grazing lands, and agroforestry resources it is difficult to gauge the location and scale of agricultural development potential, to see where specific policies and technologies are bringing about visible change, or where, for example, further expansion of the cropland frontier might involve tradeoffs with valuable habitat or other ecosystem services. Satellite-based land cover data (together with agricultural statistics reported on an administrative basis) offer practical insights into the distribution, type, and intensity of agriculture practices at different spatial scales.
While the trend is toward higher and higher spatial resolution of satellite-based land cover products, the reliability with which we can consistently delineate cultivated areas in sub-Saharan Africa varies widely. While land cover datasets typically include cropland and cropland mosaic classes, each dataset is derived using different satellite sensors, processing criteria and classification thresholds. It remains a challenge, therefore, for individuals and organizations working with these datasets to derive and maintain a reliable ‘picture’ of the geographical extent and intensity of cultivation (see the GeoWiki site for an effort to systematically validate and improve the quantification of cropland using remotely sensed data).
The primary interest of HarvestChoice is in three broad types of land cover: cropland areas, irrigated areas, and livestock grazing/pasture areas. Typically within the standard HarvestChoice 5 arc minute grid cell (about 10x10 km at the equator) there are a number of land cover types, and thus each land cover type is represented as a proportional share as well as an area amount within each HarvestChoice grid cell.
The MAPPR and ADViz&R tools provide access to the following land cover variables:
- The total land area within each 5 arc minute grid cell (the exact area of such a grid cell varies with latitude)
- The net land area within each grid cell excluding water bodies
- The area of rainfed crop land
- The area equipped for irrigation
- The area of pasture/grazing land