拘束された地下水面を下方にもつ裸地蒸発について

Abstract

In order to elucidate the evaporation mechanism from bare land, a laboratoryexperiment of evaporation from a sand layer was carried out by applying turbulentwind on the surface of the layer through a windtunnel. The sand layer has watertable at a fixed depth, and speed, temperature and humidity of the wind werecontrolled to be always constant. In particular to explore the effect of wind speedon the evaporation, the speed was changed at various water table depths. Throughthe experiment we have found out the following. The effect of the appliedturbulent wind penetrates into the sand layer, so that the wind affects theevaporation process like water vapour transfer in the sand layer. The effect alsoseemed to appear on the downward heat flux in a bone-dry zone above theevaporating front depth, related to the turbulent diffusive exchange between airsabove and beneath the sand layer surface.