Secondary dunes (or rear dunes) are located farther inland
(from the foredune or primary dune) and are not often
directly exposed to marine influences. (http://www.crd.bc.
ca/watersheds/ecosystems/coastalsanddunes.htm)
As Davies (1980) noted, his scheme is not entirely satisfactory. He stated that transgressive dunes are derived
from the erosion of primary vegetated dunes, but later in
their evolution may receive sand directly from the beach.
We now know that transgressive dunefields and dune
sheets may be initiated from erosion of foredunes or parabolic dunefields, but may be equally initiated from the
backshore without any vegetated dunes ever being present
(Hesp and Thom, 1990; Hesp and Walker, 2013).
Transgressive dunes are therefore also “free primary
dunes.” It is common to now include Davies’ (1980) “free
primary dunes” (e.g., transverse ridges, barchans, etc.)
under a broader classification of transgressive dunefields,
so his class of free primary dunes completely overlaps
with secondary transgressive dunes and sheets.
It could be argued that the terms “primary dunes” and
“secondary dunes” should now be abandoned given we
understand much more about coastal dune evolution,
dynamics, and coastal dunefield classification (Hesp,
2002, 2011; Hesp and Walker, 2012).
Bibliography
Davies, J. L., 1980. Geographical Variation in Coastal Development. London: Longman.
Hesp, P. A., 2002. Foredunes and blowouts: initiation, geomorphology and dynamics. Geomorphology, 48, 245–268.
Hesp, P. A., 2011. Dune coasts. In Wolanski, E., and McLusky, D. S.
(eds.), Treatise on Estuarine and Coastal Science. Waltham:
Academic Press, Vol. 3, pp. 193–221.
Hesp, P. A., and Walker, I. J., 2013. Aeolian environments: coastal
dunes. In Shroder, J., Lancaster, N., Sherman, D. J., and
Baas, A. C. W. (eds.), Treatise on Geomorphology. San Diego:
Academic
Press.
Aeolian
Geomorphology,
Vol.
11, pp. 109–133.
Psuty, N. P., 2008. The coastal foredune: a morphological basis for
regional coastal dune development. In Martinez, M. L., and
Psuty, N. P. (eds.), Coastal Dunes Ecology and Conservation.
Berlin: Springer. Ecological Studies, Vol. 171.
Cross-references
Back Dune
Foredune
SEDIMENT BUDGETS
Wenyan Zhang
MARUM - Center for Marine Environmental Sciences,
University of Bremen, Bremen, Bremen, Germany
Synonyms
Sedimentary budget
Definition
A sediment budget is an accounting of sediment volumes
entering and exiting a particular region of an estuary or
coast on the temporal scale of interest.
Introduction
Analysis of sediment budget is regularly applied in coastal
and estuarine sciences and management studies to aid in
understanding sediment sources, sinks, and transport pathways in a selected region of an estuary or coast within
a predefined period of time. Depending on the temporal
and spatial scales of interest, different hierarchies of
knowledge complexity may be involved in accounting of
sediment fluxes, sources, and sinks from different processes that give rise to additions and subtractions within
the system (Slaymaker, 1997). For example, a coastal
engineer may be interested in the physical processes
(e.g., waves, currents) inducing sediment volume change
at an inlet or a channel in a period of years or decades
but may neglect the biological and chemical compositions
of the sediment and their interactions with the environment. A marine biologist or chemist may be interested in
the organic matter carried by mud that enters or exits
a bay but probably has no interest in the volume change
of gravels. A comprehensive study on the geomorphological history of a coastal system or a large lake, however,
has to take into account all possible sources and sinks that
contribute to the sediment budget. Thus, to construct the
sediment budget for a specific estuary or coastal system
on a temporal scale, possible sources, sinks, and transport
processes must be identified prior and their temporal and
spatial variations have to be integrated into analysis. The
sediment budget of a coastal system or an estuary is usually constructed through the following procedures.
Procedures
1. Development of a “conceptual sediment budget” for
the research area is recommended in the planning stage
prior to making detailed calculations (Dolan et al.,
1987). The conceptual budget serves as a qualitative
model giving a regional perspective of possible
sources, sinks, and transport processes, containing the
effects of specific morphological units (e.g., shoals,
inlets, cliffs, and anthropogenic structures). The conceptual model can be constructed in part by referring
to existing sediment budgets developed for other sites
with similar environmental settings (Rosati, 2005),
and incorporating additional possible sediment sinks,
sources, and transport pathways in the research area.
An example of a conceptual sediment budget
constructed based on existing data for a coastal system
is shown in Figure 1c.
2. Collecting available datasets for the research area that
are commonly used in sediment budget analysis. These
may include (1) digital elevation models (DEM) covering both the terrestrial and subaqueous parts of the area
550
SEDIMENT BUDGETS
(from the foredune or primary dune) and are not often
directly exposed to marine influences. (http://www.crd.bc.
ca/watersheds/ecosystems/coastalsanddunes.htm)
As Davies (1980) noted, his scheme is not entirely satisfactory. He stated that transgressive dunes are derived
from the erosion of primary vegetated dunes, but later in
their evolution may receive sand directly from the beach.
We now know that transgressive dunefields and dune
sheets may be initiated from erosion of foredunes or parabolic dunefields, but may be equally initiated from the
backshore without any vegetated dunes ever being present
(Hesp and Thom, 1990; Hesp and Walker, 2013).
Transgressive dunes are therefore also “free primary
dunes.” It is common to now include Davies’ (1980) “free
primary dunes” (e.g., transverse ridges, barchans, etc.)
under a broader classification of transgressive dunefields,
so his class of free primary dunes completely overlaps
with secondary transgressive dunes and sheets.
It could be argued that the terms “primary dunes” and
“secondary dunes” should now be abandoned given we
understand much more about coastal dune evolution,
dynamics, and coastal dunefield classification (Hesp,
2002, 2011; Hesp and Walker, 2012).
Bibliography
Davies, J. L., 1980. Geographical Variation in Coastal Development. London: Longman.
Hesp, P. A., 2002. Foredunes and blowouts: initiation, geomorphology and dynamics. Geomorphology, 48, 245–268.
Hesp, P. A., 2011. Dune coasts. In Wolanski, E., and McLusky, D. S.
(eds.), Treatise on Estuarine and Coastal Science. Waltham:
Academic Press, Vol. 3, pp. 193–221.
Hesp, P. A., and Walker, I. J., 2013. Aeolian environments: coastal
dunes. In Shroder, J., Lancaster, N., Sherman, D. J., and
Baas, A. C. W. (eds.), Treatise on Geomorphology. San Diego:
Academic
Press.
Aeolian
Geomorphology,
Vol.
11, pp. 109–133.
Psuty, N. P., 2008. The coastal foredune: a morphological basis for
regional coastal dune development. In Martinez, M. L., and
Psuty, N. P. (eds.), Coastal Dunes Ecology and Conservation.
Berlin: Springer. Ecological Studies, Vol. 171.
Cross-references
Back Dune
Foredune
SEDIMENT BUDGETS
Wenyan Zhang
MARUM - Center for Marine Environmental Sciences,
University of Bremen, Bremen, Bremen, Germany
Synonyms
Sedimentary budget
Definition
A sediment budget is an accounting of sediment volumes
entering and exiting a particular region of an estuary or
coast on the temporal scale of interest.
Introduction
Analysis of sediment budget is regularly applied in coastal
and estuarine sciences and management studies to aid in
understanding sediment sources, sinks, and transport pathways in a selected region of an estuary or coast within
a predefined period of time. Depending on the temporal
and spatial scales of interest, different hierarchies of
knowledge complexity may be involved in accounting of
sediment fluxes, sources, and sinks from different processes that give rise to additions and subtractions within
the system (Slaymaker, 1997). For example, a coastal
engineer may be interested in the physical processes
(e.g., waves, currents) inducing sediment volume change
at an inlet or a channel in a period of years or decades
but may neglect the biological and chemical compositions
of the sediment and their interactions with the environment. A marine biologist or chemist may be interested in
the organic matter carried by mud that enters or exits
a bay but probably has no interest in the volume change
of gravels. A comprehensive study on the geomorphological history of a coastal system or a large lake, however,
has to take into account all possible sources and sinks that
contribute to the sediment budget. Thus, to construct the
sediment budget for a specific estuary or coastal system
on a temporal scale, possible sources, sinks, and transport
processes must be identified prior and their temporal and
spatial variations have to be integrated into analysis. The
sediment budget of a coastal system or an estuary is usually constructed through the following procedures.
Procedures
1. Development of a “conceptual sediment budget” for
the research area is recommended in the planning stage
prior to making detailed calculations (Dolan et al.,
1987). The conceptual budget serves as a qualitative
model giving a regional perspective of possible
sources, sinks, and transport processes, containing the
effects of specific morphological units (e.g., shoals,
inlets, cliffs, and anthropogenic structures). The conceptual model can be constructed in part by referring
to existing sediment budgets developed for other sites
with similar environmental settings (Rosati, 2005),
and incorporating additional possible sediment sinks,
sources, and transport pathways in the research area.
An example of a conceptual sediment budget
constructed based on existing data for a coastal system
is shown in Figure 1c.
2. Collecting available datasets for the research area that
are commonly used in sediment budget analysis. These
may include (1) digital elevation models (DEM) covering both the terrestrial and subaqueous parts of the area
550
SEDIMENT BUDGETS