Monitoring of soil moisture in backfilled soil for conservation of an Ancestral Pueblo an great house in Chaco Canyon

Abstract

An automated monitoring station, with climate sensors and a three-dimensional array of soil moisture sensors, was installed to document moisture-content changes in backfilled soil covering an Ancestral Pueblo an ‘great house’ at Chaco Culture National Historic Park, New Mexico, USA. The objective was to evaluate the performance of a geomembrane installation in the soil. Prior to its installation of the geomembrane, we observed that precipitation in winter and spring penetrated only 60–90cm into the fill during the first year after backfilling. A significant amount of moisture evaporated from the surface during the summer months, consequently the driest region was at the surface. In the following twenty-four months we observed continued dissipation of the trapped moisture towards the surface. The installation of the geomembrane system during the second year maintained a stable and dry soil environment, indicating effective surface removal of precipitation and preventing moisture penetration deeper into the soil.