Keyline Design

What is keyline design?

Keyline design begins with a simple observation: rain does not fall evenly useful. On a slope, water gathers in the valleys and leaves the ridges dry, and when it moves too fast it carves gullies and strips away soil. Keyline design reads the exact shape of the land — its ridges, valleys and the subtle "keypoints" where a slope changes steepness — and uses that geometry to redirect water.

By cultivating or planting along lines set at a slight angle to the true contour, water is gently guided away from the wet valleys and toward the dry ridges as it flows. Instead of rushing downhill in the valleys, it spreads out across the whole slope and has time to sink in. The soil itself becomes the reservoir.

The method was created by P. A. Yeomans in Australia in the 1950s, on land as dry and demanding as much of the Mediterranean. It has since become a cornerstone of permaculture and regenerative land planning worldwide.

How Terra Humana understands it

Terra Humana treats water as the first question of any dry-land restoration. Before deciding what to plant, we ask where the rain goes. Keyline design answers that question in the language of the land itself, working with the slope rather than fighting it with pumps and pipes.

It reflects a broader conviction in our work: that the most powerful tools are often the ones that redirect natural forces rather than replace them. A hillside re-shaped along its keylines catches its own water, builds its own soil, and needs far less intervention over time — resilience designed in from the start.

Keyline design in practice

At Sa Medada, near Jerzu, Terra Humana reads the contours of the land to plan where trees, swales and planting rows should go, so that water-harvesting earthworks can follow the slope's natural pattern — catching the heavy autumn and winter rains high on the land and releasing them slowly through the dry months, rather than losing them in a single flood. This is early, patient work, laid out zone by zone.

This is long-term, patient work: earthworks and tree roots together reshape how a whole hillside holds water, and the benefits deepen over years. What Terra Humana observes and records here — how much longer the land stays green, how the soil changes — becomes practical knowledge for anyone restoring dry Mediterranean ground.