As water allocations tighten across the Ebro basin, maize and vineyard growers face increasingly difficult decisions about when — and how much — to irrigate. By combining seasonal forecasts from the C3S Agriculture Service with local agronomic knowledge, irrigation communities in the Ebro Valley are planning water use weeks ahead instead of reacting to shortages as they arrive.
The Ebro Valley is one of Spain's most productive agricultural regions, supporting large areas of irrigated maize, alfalfa, fruit orchards and vineyards. Its water supply depends heavily on winter and spring precipitation stored in reservoirs across the Pyrenees. In recent years, recurrent drought has forced basin authorities to reduce seasonal water allocations, sometimes at short notice and in the middle of the growing season.
Through the C3S Agriculture Service, the region's irrigation communities now receive seasonal forecasts of precipitation, temperature and evapotranspiration tailored to agricultural decision-making. These are translated into agroclimatic indicators — such as expected crop water demand and probability of allocation restrictions — that map directly onto the decisions growers have to make each spring.
From forecast to field decision
Each month between February and June, the service publishes an outlook for the basin combining seasonal climate forecasts with reservoir status and snowpack conditions. Advisors use it to help farmers choose between full-season maize and shorter-cycle varieties, decide which plots to fallow, and schedule deficit irrigation for vineyards where a controlled water stress can even improve grape quality.
In the 2026 season, the February outlook indicated a high probability of below-average spring precipitation. Several irrigation communities responded by agreeing reduced maize sowing areas and pre-booking water for the most sensitive growth stages. When the basin authority confirmed a 30% allocation cut in May, the adjustment was already largely absorbed.