Agriculture is an important pressure on water resources and the relationship between water availability and food production is critical for a human population in continuous growth. Improving water productivity of irrigated land in semiarid areas in the Mediterranean Basin is thus considered a priority at European level.
Irrigation water saving techniques such as Regulated Deficit Irrigation (RDI) focus in decreasing water use while maintaining productivity and they widely neglect drainage. However, it is necessary to keep a flow of water drainage to assure the elimination of the excess of salts (originally present in the soil or present in the irrigation water) and the excess of water during long rainy periods that occurs even in semiarid areas. Improving irrigation water efficiency is necessary but keeping in mind that a fraction of applied water needs to be leached to avoid salinization and becoming non-productive in the long run. Despite this need, drainage amounts are scarcely monitored in irrigation districts.
Water drainage in both amount and quality affects the quality of rivers as they are usually the main sink of drainage waters. The quality of drainage water will both depend on soil salinity as well as the quality of irrigation water. Drainage transforms nutrients and hydrologic dynamics and stream configuration and wetland ecosystems. Reduced surface storage and increased effective drainage area can modify the dynamics and flows in larger streams and rivers. Cumulatively, these changes have profound implications for aquatic ecosystems and biodiversity.
In this context, IDEWA aims to bridge the gap between potential and actual irrigation performance in the Mediterranean by developing the remote sensing based monitoring tools that help i) close the water budget across the field and basin scales by explicitly taking into account drainage to ensure sustainable agriculture and ii) assess the drainage impact on stream flow. Those agriculture and water management tools will be key for ecosystems and water management guidance.