Monitoring of a suburban environment: Soil-plant-atmosphere and clay movements

Tree roots remove and re-distribute soil moisture. If the soil suffers seasonal unsaturation and is essentially clay, the ground will experience greater settlement than normal during the drying months. Of great concern to building authorities, engineers and the community is the potential damage to buildings and infrastructure that may ensue. The Australian Standard for construction of residential footings has, since 2011, incorporated some broad guidelines for estimating the additional drying settlement due to trees. These rules require extensive validation. This paper describes the establishment of a field site to study the interactions between the weather, the foundation soil and four species of trees (about 12 years old), planted in streets in a suburb of Adelaide, Australia. Selected initial monitoring data are presented, which concern initial potential reference evapotranspiration, soil suction profiles, soil moisture changes and soil movement near two Australian tree species; paperback and Queensland box. The ultimate aim of the research is to develop better numerical modelling of the impacts of trees on clay soils.