Yeoman’s Nevallan Farm P.A Yeoman’s second grazing property he
developed is called “Nevallan”, nearby Yobarnie on the outskirts of Sydney, Australia. Here, you can see both the integration of
farm ponds for irrigation and belts of trees, which were planted and were also left in that
pattern when the land was cleared. Trees provided many functions in Yeoman’s
farm designs. As wind protection and shelter for livestock,
as timber yields, for soil stability through erosion control, and as wildlife habitat and
mulch production. The spacing of the trees is such that the
height of the top of one row is at the elevation of the bottom of the next row, so the tree
belts form a continuous break to drying winds, keeping the soils hydrated for longer and
sheltering crops and animals. Just as on Yobarnie, off-contour diversion
drains collect water from the entire landscape and concentrate it in reservoirs. You can see that the tree belts follow these
water flow lines. The reservoir on the ridge has water diverted
into it from storm water that runs off of the homestead area that sits atop the ridge. It is also filled by pumping water from the
low pond along the creek. The water is then released by gravity to flood
irrigate the land below each reservoir through irrigation canals. More contemporary Keyline designs do not use
flood irrigation, as you must be quite water-rich to afford that. Today, water from Keyline reservoirs is used
to supply pressurized irrigation systems like driplines or sprinklers. The same principals of storing water high
in the landscape apply for gravity distribution of water, whether it’s flood or drip or
sprinklers.
