EFFECTS OF DIFFERENT COVERING PAVEMENT ON SUBSURFACE SOIL TEMPERATURE AND MOISTURE BY LONG-TERM IN-SITU OBSERVATION

An in-situ observation station is constructed to study the effects of different ground covers(asphalt, concrete, porous brock, grass and bare soil) on subsurface soil temperature and moisture. After about two years period of observation, datas of soil temperature and moisture at different depths are obtained and analyzed. The results show that the subsurface soil temperature and moisture are significantly influenced by pavement materials. The average soil temperature under artificial hard pavements(asphalt, concrete and porous brock) is much higher than that under natural covers(grass and bare soil).Especially, the subsurface soil temperature under asphalt pavement is also higher than that under porous pavement. It is also found that soil moisture under porous pavement is higher than that under asphalt and concrete pavement, while the soil moisture under natural covers is generally lower than that under artificial hard pavements. The results indicate that porous pavement is effective in retaining soil moisture and reducing soil temperature, and it is more reliable than nonporous pavement for balancing the urban thermal environment. During the urbanization process, it is therefore suggested that porous pavement material should be considered as priority option for policy makers and planners so as to improve urban ecological environment and reduce urban heat island effect.