Reclamation of agricultural land after planned coal mine subsidence

This chapter deals primarily with subsidence problems associated with longwall mining. Longwall mining causes immediate subsidence of the surface. Because essentially all of the subsidence occurs quickly, within a few weeks to months after undermining, most surface damage can be predicted and mitigated. Research on the reclamation of lands subsided by longwall mining is limited. The subsidence pattern at the surface is a reflection of the coal extraction pattern underground in the coal mine. The most serious subsidence impact on agricultural soils is due to excess wetness. This is usually caused by disruption of surface drainage but also can be due to lowering of the land surface below the elevation of the seasonally high water table. Because of high water tables or inadequate surface drainage, wet soils are more difficult to manage for conventional agricultural crops, must be drained to increase productivity, and are more sensitive to subsidence.