Coastal systems are amongst the most dynamic in geomorphology and the most
troublesome for environmental managers and civil engineers. This is because their
landform and process regimes are characterised by rapid change over the short term
(days and weeks) - making them difficult to predict and manage over the medium term
(periods of months and years). This dynamic behaviour is determined by the inherent
variability of coastal process forcing: the combined action of reversing tidal flows and
directionally varying wind waves on coastal sediments means that the whole shape of
the coastline can be rapidly changed under storm conditions. This is especially true on
low depositional coasts and in estuaries which are characterised by beach barriers,
dunes and salt marshes as in both cases the unconsolidated materials are particularly
mobile. Around the low depositional coasts of the North Sea large tidal ranges and
frequent storms mean coastlines exhibit complex spatial and temporal behaviour.
Although there has been significant progress in the understanding of
nearshore processes and landforms on low depositional coasts over the last 20 years
(Carter, 1988), physical models have proved difficult to extend from the timescales of
a single tidal cycle to the multi-year prediction periods required by environmental
managers and engineers. One research strategy has been to attempt to scale up coastal
modelling from the short term spatial and temporal scale (where the full mechanics of
all the processes must be represented) to medium term models (where the mechanics of
the processes must be aggregated in some way) (Martinez and Harbaugh, 1993). A
second research strategy has focussed on the investigation of the medium term
morphodynamics of specific coastal sites. By monitoring actual morphological
changes and correlating them with real energy inputs from waves and tides it has been
possible to study the nature of medium term change directly by exploring the
correlations of energy input and morphological change.
Birkbeck College and Babtie Group are currently employing both strategies in
parallel in a study of the morphodynamics of spits and nesses on the East Anglian
coast of England as part of the UK Ministry of Agriculture, Fisheries and Food
(MAFF) sponsored Coastal Area Modelling for the Long Term (CAMELOT)
programme. The aims are firstly to develop a better understanding of the interactions
between coastal processes and form on low depositional coasts, and secondly, to study
the spatial and temporal patterns of landform response (spits and ness shape and
elevation) to process forcing (wave and tide energy inputs). This knowledge will allow
more informed management intervention (by hard or soft engineering) on low
depositional coasts by ensuring that developments are appropriate for the spatial and
temporal scales of the change occurring.
Examples of such benefits could be the design of sea defences so that they
have a lifetime equal to the time that a natural feature remains in a supporting
position. An example would be the case of a sedimentary barrier such as a spit (e.g.
the Spey spit, Scotland) which may progressively extend across a vulnerable urban
frontage providing natural protection from wave energy (Riddell, 1995). If and when
the spit is breached and is starved of sediment supply it may shorten and decline in
Introduction
J. Raper et al.
400
troublesome for environmental managers and civil engineers. This is because their
landform and process regimes are characterised by rapid change over the short term
(days and weeks) - making them difficult to predict and manage over the medium term
(periods of months and years). This dynamic behaviour is determined by the inherent
variability of coastal process forcing: the combined action of reversing tidal flows and
directionally varying wind waves on coastal sediments means that the whole shape of
the coastline can be rapidly changed under storm conditions. This is especially true on
low depositional coasts and in estuaries which are characterised by beach barriers,
dunes and salt marshes as in both cases the unconsolidated materials are particularly
mobile. Around the low depositional coasts of the North Sea large tidal ranges and
frequent storms mean coastlines exhibit complex spatial and temporal behaviour.
Although there has been significant progress in the understanding of
nearshore processes and landforms on low depositional coasts over the last 20 years
(Carter, 1988), physical models have proved difficult to extend from the timescales of
a single tidal cycle to the multi-year prediction periods required by environmental
managers and engineers. One research strategy has been to attempt to scale up coastal
modelling from the short term spatial and temporal scale (where the full mechanics of
all the processes must be represented) to medium term models (where the mechanics of
the processes must be aggregated in some way) (Martinez and Harbaugh, 1993). A
second research strategy has focussed on the investigation of the medium term
morphodynamics of specific coastal sites. By monitoring actual morphological
changes and correlating them with real energy inputs from waves and tides it has been
possible to study the nature of medium term change directly by exploring the
correlations of energy input and morphological change.
Birkbeck College and Babtie Group are currently employing both strategies in
parallel in a study of the morphodynamics of spits and nesses on the East Anglian
coast of England as part of the UK Ministry of Agriculture, Fisheries and Food
(MAFF) sponsored Coastal Area Modelling for the Long Term (CAMELOT)
programme. The aims are firstly to develop a better understanding of the interactions
between coastal processes and form on low depositional coasts, and secondly, to study
the spatial and temporal patterns of landform response (spits and ness shape and
elevation) to process forcing (wave and tide energy inputs). This knowledge will allow
more informed management intervention (by hard or soft engineering) on low
depositional coasts by ensuring that developments are appropriate for the spatial and
temporal scales of the change occurring.
Examples of such benefits could be the design of sea defences so that they
have a lifetime equal to the time that a natural feature remains in a supporting
position. An example would be the case of a sedimentary barrier such as a spit (e.g.
the Spey spit, Scotland) which may progressively extend across a vulnerable urban
frontage providing natural protection from wave energy (Riddell, 1995). If and when
the spit is breached and is starved of sediment supply it may shorten and decline in
Introduction
J. Raper et al.
400