Irrigation: a tool to evaluate and encourage water savings

In France, irrigation is unavoidable for some crops and in some regions. Given the pressures currently affecting water resources, particularly in the agricultural sector, solutions have been implemented to economize and improve water management. A European regulation in support of rural development[1] ensures that farmers using irrigation (15% of farms in France[2]) are able to receive funding when changing their irrigation equipment. There is one condition: they must achieve savings of between 5 and 25%, without any corresponding drop in crop output. When creating their grant files, farmers must therefore be able to quantify the value of any anticipated water savings.

How can they know this “beforehand”? The job given to Irstea by the Ministry for Agriculture and Food was to create a simple and reliable tool to evaluate in advance any potential water savings that may be achieved by changing irrigation equipment. “Until now, farmers, irrigation advisers or grant file instructions used commonly agreed values, issued by experts. These generic values did not take into account specific irrigation conditions, such as crop or soil types, climate or the state of the equipment currently in use in the plot,” explains Claire Serra-Wittling, a research engineer at the Montpellier G-Eau unit and project leader.

Data that represent the agroclimatic context and irrigation systems

Specializing in optimizing irrigation techniques, Irstea's scientists gathered the results of experiments and practical monitoring of farming practices comparing water savings from across the region by various organizations (chambers of agriculture and technical institutes, experimental stations, farming cooperatives, land developers). In this way, over 30 references were collected and analyzed. “The database provides a good representation of the French regions involved in irrigation. It also brings together all the main systems used in mainland France, except for gravity fed irrigation[3], for large crops (particularly corn), forests or market gardens,” specifies Serra-Wittling. In addition to comparing the amount of water used by old and new equipment, and between different irrigation systems, the project made it possible to study the impact of irrigation with or without monitoring tools (tensiometers, ground humidity sensors, dendrometers, ground mapping, etc.).

A reliable benchmark now available

Using an analysis of the data, scientists created a benchmark providing the value of achievable water savings for each irrigation system (instructions are provided to adapt these values to specific local agro-pedo-climatic conditions). Designed to be integrated into an easy-to-use software, the results will be used as a benchmark for grant request files created by Regional Councils and Departmental Land Divisions.

Additionally, by analyzing the effectiveness of various irrigation systems using the Optirrig software (analysis and optimization tool for various irrigation scenarios, designed by Irstea), scientists were able to uncover sources of wasted water (e.g. drainage due to the application of too much water) and corresponding volumes. Their conclusions? Water losses can be reduced by changing irrigation equipment or technology (reducing wind drift, direct evaporation or ground evaporation) as well as by changing irrigation behavior, particularly through the use of monitoring equipment to provide high quality water at the right time. “This observation means we support systematic grants for monitoring systems, in addition to the irrigation systems themselves,” concludes Claire Serra-Wittling.

Currently limited to specific crops and to the mainland only, the benchmark data will gradually be expanded to include other crops (beetroot, potatoes, red berries, nuts, etc.), as well as other regions with different environmental characteristics, such as Martinique or La Reunion. At the same time, at the request of the Ministry of Agriculture, research will continue to determine the impact on changing irrigation systems on costs, along with any eventual energy and labor savings. These are two key criteria used by farmers when deciding on their choice of technology. The next updated version of the tool will be available in early 2019.

Download the final report Evaluation of water savings for plots achievable by modernizing irrigation systems, C. Serra-Wittling and B. Molle, September 2017 (benchmark and instructions available on pages 57 to 59).

For more information

[1] European Regulation no. 1305/2013 - Article 46, point 4. European Agricultural Fund For Rural Development (EAFRD).

[2] Source: Report no. 14061 CGAAER - Official policy on irrigation in France.

[3] Gravity fed irrigation involves flooding crops.