Experimental and Numerical Study on the Effect of the Rain Infiltration with the Increase of Surface Temperature
Journal of Korean Society of Environmental Engineers
지표면 온도상승이 빗물의 토양침투에 미치는 영향에 대한 실험 및 수치 해석적 연구
It is generally known that the increase of the Earth surface temperature due to the global warming together with the land desertification by rapid urban development has caused severe climate and weather change. In desert or desertification land, it is observed that there are always severe flooding phenomena, even if desert sand has the high porosity, which could be believed as the favorable condition of rain water infiltration into ground water. The high runoff feature causes possibly another
... possibly another heavy rain by quick evaporation with the depletion of underground water due to the lack of infiltration. The basic physics of desert flooding is reasonably assumed due to the thermal buoyancy of the higher temperature of the soil temperature than that of the rain drop. Considering the importance of this topic associated with water resource management and climate disaster prevention, no systematic investigation has, however, been reported in literature. In this study, therefore, a laboratory scale experiment together with the effort of numerical calculation have been performed to evaluate quantitatively the basic hypothesis of run-off mechanism caused by the increase of soil temperature. To this end, first, of all, a series of experiment has been made repeatedly with the change of soil temperature with wellsorted coarse sand having porosity of 35% and particle diameter, 2.0 mm. In specific, in case 1, the ground surface temperature was kept at 15℃, while in case 2 that was high enough at 70℃. The temperature of 70℃ was tested as this try since the informal measured surface temperature of black sand in California's Coachella Valley up to at 191 deg. ℉ (88℃). Based on the experimental study, it is observed that the amount of runoff at 70℃ was higher more than 5% compared to that at 15 ℃. Further, the relative amount of infiltration by the decrease of the surface temperature from 70 to 15℃ is about more than 30%. The result of numerical calculation performed was well agreed with the experimental data, that is, the increase of runoff in calculation as 4.6%. Doing this successfully, a basic but important research could be made in the near future for the more complex and advanced topic for this topic.