Drip irrigation hoses snake through rows of tiny green sprouts emerging from dry, cracked ground in Spain.

Photo: Miguel Sotomayor / Getty Images

Growing pressure on water sources from diverse water demands, as well as uses threatened by uncertain regional climate conditions, have increased the use of unconventional water resources (e.g. reclaimed water) to compensate for the water deficit in Spain. Specifically, recycled urban wastewater has become an attractive, reliable and safe alternative to regulated groundwater pumping in over-drafted aquifers for agricultural irrigation.

However, wastewater reuse for irrigation still lags behind stated national goals and may even conflict with environmental and recreational water uses in this high-water stress region. This project uses a hydro-economic model to explore the potential for reclaimed water reuse in agriculture and effective water resource management under climate uncertainties. Management alternatives include different levels of reclaimed water reuse from urban wastewater treatment plants in the region, while climate uncertainty is represented by projected precipitation and temperature changes under different representative concentration pathways (4.5 and 8.5).

We evaluate the quantity of avoided groundwater withdrawal, area of crops irrigated with reclaimed water, impact on farmers’ income, and streamflow available for environmental uses under the combined climate and management scenarios. Such evaluations are subject to reclaimed water availability and groundwater pumping restrictions determined for drought conditions. Our results provide valuable insights on economic and environmental implications of reclaimed water reuse. They can support responsible decision and policy options to maximize the use of these alternatives for integrated and sustainable water resource management in semi-arid regions.