Elevation data

Description

Data describing the elevation of the terrain and its derivatives, such as slope and aspect.

Rationale

Height and height difference influence many processes relevant for agriculture, such as the flow of water, erosion, temperature, and exposure to wind and sun. Sharing this information helps value-chain actors to better understand the local production environment in different places.

Key datasets

• Digital elevation model
• Elevation maps
• Height points
• Slope
• Aspect
• Catchments
• Drainage
• Erosion susceptibility

Expected impact:

Farmer use:

• Farmers can get better farm advice via SMS or mobile apps when the message is adjusted to their location and local topography that may affect temperature, exposure, erosion, rainfall, climate, weather extremes, etc.

Use by other actors:

• Extension officers can gain better insights into local agro-ecological growing conditions (erosion, exposure, temperature), resulting in better advice to the farmers.
• Better planning of logistical services taking into account the variations in the terrain.
• Better insights into local agro-ecological growing conditions contributes to a more accurate risk assessment for financial service providers
• Better insights into local agro-ecological growing conditions, erosion potential and accessibility leads to better rural development project planning by NGOs.

Readiness

Satellite technology provides elevation measurements globally at 30m resolution as open data. This data is applicable for many purposes, but is mainly accessible by experts and not validated in detail for the whole dataset. Many governments make the effort of creating their own data from these sources by improving the data, correcting errors and filling data gaps. In addition, derivative datasets such as drainage and erosion susceptibility maps are being produced . Some governments also create more detailed elevation data based on field measurements or airborne laser scanning techniques (Lidar). This highly accurate data is relevant for water management, drainage, flooding and irrigation. These types of datasets are already digital and can easily be published as open data.

Examples of implementation

• At a global scale datasets are available at 30 m resolution as open data: (1) Aster DEM https://asterweb.jpl.nasa.gov/gdem.asp based on stereo imagery; (2) SRTM DEM 1 arcsecond (NASA, Global, 30m), https://lta.cr.usgs.gov/SRTM1Arc based on radar technology.
• CGIAR has refined the SRTM elevation model, filling data gaps and providing an improved dataset at a 90m resolution as open data. http://www.cgiar-csi.org/data/srtm-90m-digital-elevation-database-v4-1
• The UK government provides their laser scanning data set as open data at 1m resolution https://environmentagency.blog.gov.uk/2015/06/16/free-mapping-data-will-elevate-flood-risk-knowledge/

Initiatives that support interoperability

• USGS Digital Elevation Model Standard http://nationalmap.gov/standards/demstds.html
• http://www.opengeospatial.org/docs/is