Local-scale evaporation and water loss distribution in surface soil as related to near-surface wind conditions and surface geometry

Local (cm) scale water loss distribution and evaporation in soil with flat and furrowed surfaces as a function of near-surface wind speed and wind direction was investigated. Four levels of average main wind speed (10 cm above furrow ridge summits, 0, 1, 3 and 5 m center dot s(-1)), three main wind directions (compared to the direction of the furrows, 0 degrees, 45 degrees and 90 degrees) and two levels of relative air humidity (70% and 86%) were considered. Experiments were conducted under controlled (wind tunnel) conditions, using 50 cm diameter and 15 cm height soil samples. For furrowed samples, 6 cm high ridges with 12 cm distance between ridge tops were used. Resulting wind speed profiles above ridge tops were relatively similar (for the same main wind speed), regardless of wind direction, but differed greatly in the valleys between ridges depending on especially wind direction. Strong indication of standing eddies on the lee side of furrow ridges for wind directions >= 45 degrees was found. Local evaporative water loss spatial distribution in furrowed soil, was strongly dependent on wind direction, while local evaporation rates depended strongly on main wind speed and relative humidity level. Significantly higher evaporative water losses were observed at the wind-exposed ridge slopes (for wind directions >= 45 degrees) compared to lee slopes. Highlights Local (cm) scale water loss in furrowed soil under windy conditions was investigated. Wind speed profiles between furrow ridges were strongly dependent on wind direction. Local water loss was significantly higher on windward slopes in furrowed soil. Local water loss spatial distribution was strongly dependent on wind direction.

Automated summary

The study investigated the local water loss in furrowed soil under windy conditions, finding that wind direction had a significant impact on the wind speed profiles between furrow ridges. Local water loss was significantly higher on the windward slopes in furrowed soil.