To enhance global food security it is essential to increase food production through the use of irrigation.
Achieving higher food production levels can be obtained by expansion of irrigated area or enhancement of irrigation performance through optimising water distribution (rehabilitation of the physical irrigation infrastructure) and through improving the irrigation water management (sufficient and timely application).
Earth Observation offers (1) the analysis of the current situation by quantifying the irrigated area and water consumption, (2) regular updates on water use in-season to adjust irrigation schedules and water distribution and get valuable insights on how water management can be improved, (3) the identification of areas in need of rehabilitation by assessing irrigation performance, water distribution and water productivity, and (3) the exploration of irrigation potential (new schemes) by looking at land suitability, identifying constraints for development and quantifying the impact on the water balance.
Irrigation system design
Satellite Earth Observation (EO) is a powerful technique for collecting spatial information relevant for irrigation system design. It adds spatial detail on soil, crop and topography to basic design criteria, such as water application, irrigation frequency and operation restrictions. For example using satellite data we can map the land cover prior to investment, identify areas of importance needing protection, assess the suitability taking into account weather and soil, and assess risks such as floods. Irrigation system design does not only involve the construction of new systems but also extensions, rehabilitations, and upgrades of existing systems. Changing environments require constant redesign to conserve water and improve services.
EO-based services help in selecting target areas for irrigation development by quantifying water stress and identifying under-performing areas in both rainfed and irrigated agriculture. Once areas have been selected, EO data can assist in determining land and irrigation suitability as well as (potential) impact of irrigation development on the water balance.
Irrigation systems operations
Regular and consistent monitoring of water distribution over large areas involves using satellite derived evapotranspiration and precipitation data are used to calculate water use. Together with weather forecasts it allows timely identification of upcoming water stress and/or use exceedance of allocated water.
Irrigation performance can be enhanced by:
- optimising water distribution (rehabilitation of the physical irrigation infrastructure); and
- by improving the irrigation water management (sufficient and timely application). This service focusses on the latter – improving water management- and is valuable to water managers at different levels, from irrigation agencies to irrigation scheme managers to the farmer. Regular updates on water use in-season allows irrigation schedules and water distribution to be adjusted and provides valuable insights on how water management can be improved.
Assessing irrigation performance
Increased water scarcity brought on by climate change, growing population and food demand, and increased competition from other sectors calls for improving water productivity and achieving more crop per drop. Traditionally, irrigation performance has been expressed in terms of efficiencies of observed flows, with a focus on the amount of irrigation water applied on the field. However, not all of the water applied will be consumed by the crop, and some of the losses in the irrigation system are actually re-used elsewhere downstream. Advanced energy balance algorithms using satellite earth observation estimate actual evapotranspiration, i.e. the water consumed by the crop. Satellite-based estimates of water consumption and water stress combined with biomass production and/or yield data provide estimates of irrigation performance, including water productivity, at scales not achievable with current conventional methods.