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of coastal sedimentary environments is restricted.
Such interactions with sedimentary systems or a
restriction in the way sediment systems respond
to increased energy levels often brings with it
a management or remediation 'cost'. Hence in
many cases, the need for management is often
driven not so much by the actual event, but as
a result of (increasing) human occupation and
modification of the environment, i.e. urbaniza-
tion of environments that will naturally respond
to changes in the energy inputs associated with
storm or flood events. The influence of urban-
ization of the coastal fringe is seen particularly
clearly in relation to estuarine environments
where large areas of intertidal land have been
claimed over a period of several centuries (see
Chapter 7). The result is often a fundamental
change in the character and extent of intertidal
land, and a suppression of an estuary's ability to
respond to changes in nearshore energy regimes
or sea-level state.
Urbanization also has major impacts upon
the hydrology of catchments and river basins,
which in turn influences the nature of sediment
movement and accumulation (see Chapter 6).
The increase in runoff rate in urban systems
leads to enhanced flooding pressures in river
systems, and this is often exacerbated by the
past removal of floodplains and river culverting,
which inhibits the accumulation of sediment.
These increases in runoff rate also have marked
impacts upon sediment transport in urbanized
river basins, with large storm events accounting
for the majority of suspended sediment trans-
port flux over short periods of time (Goodwin
et al. 2003; Old et al. 2003).
Another highly significant anthropogenic
impact on sediments is that of sediment com-
position and quality. The increase in contamin-
ant loading in sediments has been extensively
documented for virtually all sedimentary sys-
tems globally, including those that are generally
assumed to be pristine. These have been docu-
mented both through monitoring programmes
on sediment composition, and sedimentary
archives of contaminant accumulation, such as
salt marshes, lakes, reservoirs and floodplains.
The former approach allows for short-term data
sets only, as monitoring programmes on sediment
composition have not been in place for long.
Longer temporal records of sediment composi-
tion may be recorded by sediments accumulating
in depositional environments (see Case Study 1.2).
The nature and length of the sediment record
will depend on a number of factors, including
sediment accumulation rates, extent of sedi-
ment disturbance and post-depositional changes.
Examples of temporal records of sediment com-
positional change for lakes and river basins can
be found in Chapter 4 and in Smol (2002). Such
compositional changes, and associated records
of environmental pollution have also been
clearly documented for saltmarsh sediments
(see Chapter 7).
1.6.3 Response of sedimentary systems to climatic
and environmental change
Given the influence that climate exerts on the
development of sedimentary environments, ongo-
ing and projected climatic and environmental
changes are potentially significant in relation
to the dynamics and functioning of most sedi-
ment systems. Climate exerts, for example, an
important influence on weathering regimes,
the hydrological cycle (including seasonality
of rainfall) and the frequency and magnitude
of high-energy (storm) events, all of which are
important in determining rates of sediment
supply and transport (e.g. Chapters 2- 4). In the
marine environment, climatic conditions also
influence environmental factors such as levels
of dissolved CO
2
and sea-surface temperatures.
These are primary controls on the distribution
and development of biogenic sedimentary deposits
(Chapter 9). Sea-level itself is a major control
both on the distribution and extent of coastal
sedimentary environments (Chapters 7 and 8)
and, because it influences base level, a major
forcing factor with fluvial systems (Chapter 3).
Hence many of the predicted changes in global
climatic conditions need brief consideration
here. These include changes in atmospheric CO
2
concentrations, increased atmospheric and sea-
surface temperatures, increased UV radiation,
changes to patterns of storm frequency and
