Precision Irrigation in the Alps: how SWAB tackles the Water Challenges

This study presents SWAB (Soil-Water-Atmosphere Advanced Budget), a state-of-the-art and highly operational modeling framework designed for precision irrigation of grapevine, apple, and olive in alpine regions, addressing the practical needs of the agricultural sector and policymakers. SWAB is based on the water budget methodology outlined in FAO Irrigation and Drainage Paper No. 56, which provides a robust framework for estimating crop water requirements. However, SWAB extends and improves this methodology by incorporating advanced parameterizations of the Soil-Plant-Atmosphere Continuum (SPAC), specifically adapted to the alpine context. This region is characterized by substantial variability in soil properties and microclimates, requiring a flexible yet precise approach. Furthermore, the model integrates crop-specific parameters tailored to the high-quality production goals of Trentino's agriculture, ensuring it meets the stringent demands of premium apple and wine production.

The study focuses on the Trentino region, where approximately 20,000 hectares of irrigated land are split nearly evenly between apple orchards and vineyards. Apple orchards produce approximately 565,000 tonnes of apples with a Gross Production Value (GPV) of around €187 million. Vineyards yield approximately 141,000 tonnes of wine grapes with a GPV of roughly €160 million. The average GPV per hectare of €17,500 underscores the critical economic importance of irrigated agriculture in the region.

Agriculture in the Alpine arc does not typically face arid conditions during the growing season, as significant precipitation, including extreme events, is observed. However, a notable decline in snowfall has been recorded, which affects the primary water reserves available in spring, crucial for the onset and maintenance of the growing season. These water stocks (reservoirs, lakes, streams) are also used for various other purposes, including ecological sustainability—such as ensuring minimum vital flow for aquatic organisms—as well as tourism and hydropower generation, thereby increasing competition for water resources, particularly during dry winters and springs.

In mountain agriculture, irrigation water is managed by Irrigation Consortia that aim to provide equitable access to all members, considering meteorological conditions to some extent, but largely independent of crop type or soil characteristics. SWAB seeks to meet local demands by estimating the required water supplies to fulfill irrigation needs of the SPAC in the alpine context, while also offering recommendations to irrigation Consortia for enhanced short-term precision irrigation management.

This study focuses on estimating the water supplies needed to meet irrigation requirements in the alpine context, with the potential for analyzing medium- to long-term trends. The results highlight how an integrated modeling approach can support sustainable water resource management in mountain agriculture, enhancing the resilience of the sector in the face of increasing competition for water and climate change.