Many of HarvestChoice spatial datasets are organized and released on 10-km grids. To make spatial analyses easier for researchers (even without having access to GIS platform), we put data layers from multiple themes together in one denormalized big table. This post describes the methodology and presents a prototype.
Starting with the Spatial Production Allocation Model (SPAM), many HarvestChoice data products are organized at 5 arc-minute (also known as 10 km) grids. We often align the grids with other additional layers and aggregate them in different ways. For example, by overlaying market accessibility and crop growing areas or livestock population, we assess the proportion of crop and/or livestock production in the high (or low) market access zones. Much of these spatial analyses are being done in GIS, but also can be quickly done through simple database operations.
As a by-product of recent exercise that overlaid agricultural production, agro-ecological characteristics, and market accessibility on the rural population in Sub-Saharan Africa (SSA), we created a simple table that lists about 300K grid cells (i.e., tiles) in SSA with related attributes, including:
- Cell ID (CELL5M; see the HCID post for more information)
- Country name
- Administrative unit name and level (source: HarvestChoice HCADMIN v1.0)
- Total cell area in ha (including water body; rough arithmetic estimate)
- Total crop land area in ha (source: SPAM v3.02)
- Agro-ecological zone (source: HarvestChoice AEZ)
- Population of 2000 in headcount - Total, rural, and urban (source: CIESIN Gridded Population of the World)
- Market accessibility in hours – Travel time to the nearest town with 20K+ population (source: HarvestChoice Travel Times)
- HarvestChoice Travel Times
- Livestock population density of 2005 in headcount - Cattle, goat, and sheep (source: FAO Global Livestock Production and Health Atlas)
- Elevation in meter (source: CGIAR-CSI SRTM 90m v4.1)
- Annual total rainfall in mm (source: WorldClim)
- Crop areas for major staple crops of 2000 in ha (wheat, rice, maize, barley, millet, sorghum, potato, sweet potato and yam, cassava, banana and plantain, soybean, beans, sugarcane, coffee, cotton, and groundnuts) (source: SPAM v3.02)
Nothing in this list of variables is new - yet we found it useful to put all the variables in one place and quickly summarize/aggregate different dimensions of characteristics; we thought that it is ideal material for the Labs! This table can be also used for multiple purposes creatively. Please suggest any significant yet missing variables - we'll try to add them for next release.
- Cell ID (CELL5M) grids in shapefile: https://hc.box.net/shared/hdg0j8esj6
- Attributes table in tab-delimited ASCII text file: https://hc.box.net/shared/n8f6cxu6ue
- Add/update crop production and area values to 2005
- Add suitability of crop production
- Market accessibility (travel time) for other town population classes (20K, 100K, 250K, and 500K)
- Update population to 2005
- ...? (Feel free to make suggestions!)