Technical Meetings – 2021

COSMOS, Scintillometer & Eddy Cov New Technologies to save Irrigation Water

Date: 23rd November 2021

Recording available here.

Tea time talk with Dr Ragab Ragab, President of ICID


Accurate estimation of irrigation water requirements could save water and minimize losses, allowing more land to be irrigated and subsequently more food to be produced. Irrigation practitioners have always faced the challenge of “when to irrigate and how much water to apply”. To answer those questions several methods have been developed, ranging from measurement based to empirical and energy balance equation based approaches. The accuracy of those methods and the scale they represent are of great importance. 

Modern technologies to measure actual evapotranspiration and subsequently the crop water requirement, such as large-aperture Scintillometer and Eddy Covariance instruments were tested and compared with the most common method of the FAO modified Penman–Monteith equation. The results indicate that the actual crop water requirement based on modern technologies could save at least 50% of irrigation water. Another benefit is that these modern technologies do not need the crop coefficient Kc, which for many irrigation practitioners is difficult to obtain. In addition, the cosmic-ray soil moisture observing system (COSMOS) was tested for its suitability in estimating the soil moisture deficit (SMD) and subsequently, the crop water requirement. The results showed that the COSMOS measurements could be useful for monitoring the soil water status and SMD in the root zone in irrigated agriculture and could be made operational for irrigation managers to determine when and how much irrigation water to apply.