Study on the Response of Hydrothermal Environment at Different Elevations (Near the Surface) to the Water Condition of Underlying Surface

Abstract In recent years, many ecological problems brought by rapid urbanization have attracted attention, but less attention has been paid to the daily variation of hydrothermal environment at small scale. In order to precisely investigate the effect of subsurface moisture conditions on the daily variation of the near-surface air-hydrothermal environment, this study was conducted from May 21 to May 24, 2019, in a quantitative water control simulation experiment in the bare ground of the University City, Yuci District, Jinzhong City, China, to compare the diurnal air-hydrothermal environment at different height (0.3 m, 1.0 m, and 1.5 m) of different ground surfaces by differential watering (0 L, 30 L, and 60 L) Variation. The results show that: 1) Under the control of other variables, the cooling effect was more obvious with the increase of irrigation amount. The average cooling effect of 30L was 0.47℃ while 60L was 0.61℃. 2) At different heights near the ground (0.3 m, 1.0 m and 1.5 m), the cooling effect was most obvious at height of 0.3m. And the temperature decreased 0.636℃, 0.400℃, 0.373℃at the three height under 30L irrigation; 0.991℃, 0.605℃, 0.226℃ under 60L irrigation. 3) The cooling effect at is more significant at daytime (0.72℃) than night (0.27℃). 4) The difference was smaller in the initial stage of irrigation, larger in the middle stage of irrigation, and smaller in the later stage of irrigation. The variation of relative humidity of air at different height near the surface is influenced by three factors: diurnal temperature variation, irrigation amount and vertical air movement day and night. Quantitative observation and research on water and heat environment can not only improve the discussion on the heat conduction mechanism of near-surface water, but also have important practical significance to the improvement of the underwater thermal environment of city.