Peat subsidence

Hayes, M. H. B. (1960). Subsidence and Humification in Peats. Ph.D. dissertation, The Ohio State University. 

Coals are generated by burial of peats, which are formed in swamps and marshes. Geographic and tectonic requirements for formation of thick peat deposits include slow subsidence, protection of the swamp from erosion by marine inundation or fluvial flood waters and a restricted supply of fluvial sediment. These requirements are met on coastal plains where most Recent peat swamps are located. Microbial activity is capable of degrading great quantities of the plant material which is the ultimate source of peat. Therefore, conditions which inhibit microbial activity are favorable for the... 

Schothorst, C. J. (1977). Subsidence of low moor peat soils in Western Netherlands. Geoderma 17, 265-271. 

Over a period of many centuries the swamp land slowly subsided while maintaining a dense forest at or near sea level. Layer upon layer of fallen vegetation was converted to peat. Mineral matter was introduced into the swamps, mainly by rivers, as suspended mud and dissolved ionic species during storms that flooded the swamp, by sea water during wind storms, and by distant volcanic eruptions that rained dust onto the swamp. 

More often than not, once a peat swamp was established on a coastal plain or delta and later covered by sediments due to land subsidence, a second swamp was established in the same region by cyclic changes in sea level and re-establishment of swamp-type vegetation. In this way, multiple layers of peat and subsequently of coal were formed. 

Use. Coastal marshland peats, when drained and cropped, undergo decomposition and a long-continued shrinkage, as do all peats. The subsidence often makes drainage a problem. In its natural condition, coastal marshland serves as a haven for birds and other wildlife. 

Much of the wetland loss occurring in coastal Louisiana is due to the deterioration of highly organic marsh soil. As discussed earlier, conversion of coastal marshes to inland open water is associated with plant stresses such as saltwater intrusion into nonsaline marshes and increased soil waterlogging as a result of subsidence. Marsh elevation decreases rapidly following plant mortality because of the structural collapse of the living root networks (DeLaune et al., 1994). The peat collapse and the associated erosion result in the conversion of marsh into open water. Conversions to open water system releases a considerable amount of carbon into the estuary where it is either decomposed or... 

Suitable These are areas underlain by shallow estuarine/deltaic deposits (clay, silt with lesser amounts of sand and gravel and variable organic matter) and riverine deposits (sand, silt and clay with minor to moderate plant remains) of less than 5 m sand. Shallow peat (less than 1 m) normally occurs as narrow belts. These areas have a moderately deep foundation level or rockline (10 to 15 m) with minor to moderate amounts of subsidence expected and fair amount of fill required. 

Okey, C.W. (1918). The subsidence of muck and peat soils. Trans. ASCE 82 396-432. 

Barrier islands overlying poorly consolidated substrates experience increased rates of relative sea level rise because of the decrease in elevation due to subsidence. These types of barrier island systems can exist near river deltas, as deltaic sediments are reworked by coastal processes, and on the open coast as islands have migrated landward over bay sediment or a peat substrate. Potentially, one-third of the more than 3,600 km of continental US barrier islands consists of a sandy island morphology that overlies poorly consolidated sediment. 

Within about a thousand years the cultivation and draining of the peat lands with wind-driven watermills, that started about 1400 ad, led to a subsidence in the coastal zone which could mount to about five meter. As this process is an indirect result of settlement and land reclamation, it cannot be considered as a proactive measure with regard to water management From about 2000 BP sand barrier aggradations at the coast ended and since 1000 ad coastal erosion started again (De Cans, 2007). 

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