Land Subsidence in Drained Histosols and Highly Organic Mineral Soils of California

This study was conducted to determine historical trends in subsidence in the Sacramento‐San Joaquin Delta and their environmental controls. Historical subsidence was determined by measuring soil surface elevation loss near electrical tower foundations and by evaluating survey data between 1922 and 1981. The data indicated that subsidence slowed with time. In the western Delta, average subsidence rates were 2.3 cm yr −1 from 1910 to 1988 and 1.5 cm yr −1 from 1952 to 1988. Spatially variability in subsidence was correlated with organic matter content of the soil ( r 2 = 0.62), which in turn was related to the depositional and drainage history of the Delta. Subsidence rates appeared to be independent of crops grown.