On a 1.2 ha hillside near Travo (Piacenza), a privately funded permaculture retrofit in 2024 installed a contour-based water retention system to rehydrate compact loamy clays and stop erosion. Using site reconnaissance and a functional analysis, the design by the Italian Permaculture Institute placed several 50×50 cm swales on level curves along primary and secondary flow paths, paired with raised beds and berms. Syntropic tree lines, placentas and food-forest bombs introduce layered, successional plantings across fruit trees, a diversified vineyard, vegetables and aromatic herbs. Mulching with wood chips and composted manure protects the soil, reduces evaporation and feeds soil biology.

With 901 mm of annual rainfall and slopes around 10 to 19 degrees, the system is sized for passive capture and infiltration. A 45 m swale is estimated to store about 20,000 L per year, and the overall swale network at least 70,000 L per year, with safe gravity overflows directing surplus to the valley. Implementation emphasised simple earthworks, precise contouring and minimal mechanical inputs, with maintenance limited to grass cutting, light pruning every three years and periodic compost applications.

Early observations show swales performing as intended, no surface erosion or on-site flooding, improved soil moisture near tree lines and clear increases in insects, birds and herb diversity. Some uneven filling occurred during heavy rain and is being addressed through refinements of inlets and overflows. The project targets flood and drought mitigation at site scale, soil and water conservation, biodiversity gains and long service life of at least 50 years, with full retention potential expected within about five years.