SummaryLand Subsidence can be the result of depletion of aquifers. Both the absolute amount and rate of subsidence are used. General Information about this IndicatorWhat is it?: Farming in the Delta has caused erosion of the peat soils and various levels of subsidence of Delta islands and other areas behind levees. Both the absolute amount that lands have subsided and the rate of change (positive or negative) in subsidence are important measures.