Seasonal Moisture Fluctuations in the Active Zone in a Humid-Subtropical Climate

Moisture fluctuation in the active zone results in ground movement and hence is one of the major issues in maintaining and servicing structures from residential buildings to transportation facilities. Also the moisture fluctuation in the ground is affected by the constructed facilities, vegetation, soil type and the geology of the region. The climate in an urban city such as Houston, Texas is classified as humid and subtropical. Houston's warmest month is July and the coldest month is January. Houston also has occasional severe weather such as flooding, tornadoes and hurricanes. In this study, over 20,000 moisture data were collected from the top 10 feet from 2500 boreholes. This data was collected in between 2000–2007. This data set was analyzed on a monthly basic to determine the monthly variation of moisture content up to a depth of about 3 m (10 feet). Also the climate changes data, the temperature and rainfall were also collected and analyzes based on a monthly basis. Based on the geo-statistical analyses, the variation in the air temperature and total monthly rainfall were correlated to the soil moisture fluctuations. Also the monthly moisture fluctuations were quantified with the soil depth.