Definition
Flocculation is a process by which particles come out of
the suspension to form flocs or larger particles, specifically in an estuarine environment.
The flocculation process is influenced by physical,
chemical, and biological factors in both terrestrial and
aquatic environments. Flood, ebb, and wave energies
drive the suspension and resuspension of sediments and
affect the formation and differential settlement of flocs.
The concentration of dissolved ions and particulate and
dissolved organic matter influences floc surface charge,
promoting flocculation as well. These factors, together
with estuarine circulation patterns, provide an important
mechanism for suspended particles to flocculate and later
settle to the estuarine floor (Eisma, 1986; Day et al., 1989;
McLusky and Elliott, 2004; Wolanski, 2007).
Bibliography
Day, J. W., Hall, C. A., Kemp, W. M., and Alejandro, Y., 1989.
Estuarine Ecology. New York: Wiley-Interscience.
Eisma, D., 1986. Flocculation and De-flocculation of suspended
matter in estuaries. Netherlands Journal of Sea Research, 20
(2/3), 183–199.
McLusky, D. S., and Elliott, M., 2004. The Estuarine Ecosystem:
Ecology, Threats, and Management. Oxford: Oxford University
Press.
Wolanski, E., 2007. Estuarine Ecohydrology. Amsterdam: Elsevier
Science.
Cross-references
Sediment Grain Size
Wave-Driven Sediment Resuspension
ESTUARINE GEOMORPHOLOGY
David M. Kennedy
Department of Resource Management & Geography,
The University of Melbourne, Parkville, VIC, Australia
Definition
Estuarine geomorphology is the study of the landforms of
an estuary. Geomorphologically, an estuary is defined as
a semi-enclosed body of water which contains landforms
derived from both fluvial and marine processes, where
the latter contain sediment that has been transported landward by wind, wave, and tidal processes.
Description
An estuary is the seaward portion of a drowned valley system (Dalrymple et al., 1992) and is divided into wave- and
tide-dominated forms (Kennedy, 2011). The geomorphology of a wave-dominated estuary is subdivided into three
zones. The marine zone occurs at the oceanward end and
is where beach-barrier systems as well as flood and ebb
tide deltas are found. The central part of the estuary is a
low-energy zone dominated by a mud basin, while at the
landward end, river deltas occur in the fluvially dominated
zone (Roy, 1984). In tide-dominated estuaries, barrier systems are absent, and the marine zone is composed of
a series of elongate subtidal bars extending far into the
estuary. The central mud basin does not occur
(Dalrymple et al., 1992; Dalrymple and Choi, 2007). In
planform these estuaries are funnel shaped, being characterized by straight marine and fluvial channels at opposite
ends of the estuary separated by a meandering channel
zone where tidal and river flows interact (Woodroffe
et al., 1993; Dalrymple and Choi, 2007).
Bibliography
Dalrymple, R. W., and Choi, K., 2007. Morphologic and facies
trends through the fluvial–marine transition in tide-dominated
depositional systems: a schematic framework for environmental
and sequence-stratigraphic interpretation. Earth Science
Reviews, 81, 135–174.
Dalrymple, R. W., Zaitlin, B. A., and Boyd, R., 1992. Estuarine
facies models: conceptual basis and stratigraphic implications.
Journal of Sedimentary Petrology, 62, 1130–1146.
Kennedy, D. M., 2011. 1.03 – tectonic and geomorphic evolution of
estuaries and coasts. In Wolanski, E., and McLusky, D. (eds.),
Treatise on Estuarine and Coastal Science. Oxford: Elsevier,
pp. 37–59.
Roy, P. S., 1984. New South Wales estuaries: their origin and evolution. In Thom, B. G. (ed.), Coastal Geomorphology in Australia.
New York: Academic, pp. 99–121.
Woodroffe, C. D., Mulrennan, M. E., and Chappell, J., 1993. Estuarine infill and coastal progradation, Southern Van Diemen Gulf,
Northern Australia. Sedimentary Geology, 83, 257–275.
Cross-references
Coastal Landforms
Estuarine Geomorphology
Geomorphological Mapping
ESTUARINE HABITAT RESTORATION
Ronald M. Thom and Amy B. Borde
Marine Sciences Laboratory, Pacific Northwest National
Laboratory, Sequim, WA, USA
Synonyms
Conservation; Creation; Enhancement; Habitat reclamation; Mitigation; Protection; Rehabilitation
Definitions
Restoration means the return of an ecosystem to a close
approximation of its previously existing condition (e.g.,
NRC, 1992; Lewis, 2000). Habitat restoration is defined
as returning the condition of an altered or disturbed habitat
to a close approximation of a former (less disturbed) or
pre-disturbance condition. In the common vernacular,
however, restoration appears to be an umbrella term
encompassing creation, enhancement, rehabilitation,
ESTUARINE HABITAT RESTORATION
273
Flocculation is a process by which particles come out of
the suspension to form flocs or larger particles, specifically in an estuarine environment.
The flocculation process is influenced by physical,
chemical, and biological factors in both terrestrial and
aquatic environments. Flood, ebb, and wave energies
drive the suspension and resuspension of sediments and
affect the formation and differential settlement of flocs.
The concentration of dissolved ions and particulate and
dissolved organic matter influences floc surface charge,
promoting flocculation as well. These factors, together
with estuarine circulation patterns, provide an important
mechanism for suspended particles to flocculate and later
settle to the estuarine floor (Eisma, 1986; Day et al., 1989;
McLusky and Elliott, 2004; Wolanski, 2007).
Bibliography
Day, J. W., Hall, C. A., Kemp, W. M., and Alejandro, Y., 1989.
Estuarine Ecology. New York: Wiley-Interscience.
Eisma, D., 1986. Flocculation and De-flocculation of suspended
matter in estuaries. Netherlands Journal of Sea Research, 20
(2/3), 183–199.
McLusky, D. S., and Elliott, M., 2004. The Estuarine Ecosystem:
Ecology, Threats, and Management. Oxford: Oxford University
Press.
Wolanski, E., 2007. Estuarine Ecohydrology. Amsterdam: Elsevier
Science.
Cross-references
Sediment Grain Size
Wave-Driven Sediment Resuspension
ESTUARINE GEOMORPHOLOGY
David M. Kennedy
Department of Resource Management & Geography,
The University of Melbourne, Parkville, VIC, Australia
Definition
Estuarine geomorphology is the study of the landforms of
an estuary. Geomorphologically, an estuary is defined as
a semi-enclosed body of water which contains landforms
derived from both fluvial and marine processes, where
the latter contain sediment that has been transported landward by wind, wave, and tidal processes.
Description
An estuary is the seaward portion of a drowned valley system (Dalrymple et al., 1992) and is divided into wave- and
tide-dominated forms (Kennedy, 2011). The geomorphology of a wave-dominated estuary is subdivided into three
zones. The marine zone occurs at the oceanward end and
is where beach-barrier systems as well as flood and ebb
tide deltas are found. The central part of the estuary is a
low-energy zone dominated by a mud basin, while at the
landward end, river deltas occur in the fluvially dominated
zone (Roy, 1984). In tide-dominated estuaries, barrier systems are absent, and the marine zone is composed of
a series of elongate subtidal bars extending far into the
estuary. The central mud basin does not occur
(Dalrymple et al., 1992; Dalrymple and Choi, 2007). In
planform these estuaries are funnel shaped, being characterized by straight marine and fluvial channels at opposite
ends of the estuary separated by a meandering channel
zone where tidal and river flows interact (Woodroffe
et al., 1993; Dalrymple and Choi, 2007).
Bibliography
Dalrymple, R. W., and Choi, K., 2007. Morphologic and facies
trends through the fluvial–marine transition in tide-dominated
depositional systems: a schematic framework for environmental
and sequence-stratigraphic interpretation. Earth Science
Reviews, 81, 135–174.
Dalrymple, R. W., Zaitlin, B. A., and Boyd, R., 1992. Estuarine
facies models: conceptual basis and stratigraphic implications.
Journal of Sedimentary Petrology, 62, 1130–1146.
Kennedy, D. M., 2011. 1.03 – tectonic and geomorphic evolution of
estuaries and coasts. In Wolanski, E., and McLusky, D. (eds.),
Treatise on Estuarine and Coastal Science. Oxford: Elsevier,
pp. 37–59.
Roy, P. S., 1984. New South Wales estuaries: their origin and evolution. In Thom, B. G. (ed.), Coastal Geomorphology in Australia.
New York: Academic, pp. 99–121.
Woodroffe, C. D., Mulrennan, M. E., and Chappell, J., 1993. Estuarine infill and coastal progradation, Southern Van Diemen Gulf,
Northern Australia. Sedimentary Geology, 83, 257–275.
Cross-references
Coastal Landforms
Estuarine Geomorphology
Geomorphological Mapping
ESTUARINE HABITAT RESTORATION
Ronald M. Thom and Amy B. Borde
Marine Sciences Laboratory, Pacific Northwest National
Laboratory, Sequim, WA, USA
Synonyms
Conservation; Creation; Enhancement; Habitat reclamation; Mitigation; Protection; Rehabilitation
Definitions
Restoration means the return of an ecosystem to a close
approximation of its previously existing condition (e.g.,
NRC, 1992; Lewis, 2000). Habitat restoration is defined
as returning the condition of an altered or disturbed habitat
to a close approximation of a former (less disturbed) or
pre-disturbance condition. In the common vernacular,
however, restoration appears to be an umbrella term
encompassing creation, enhancement, rehabilitation,
ESTUARINE HABITAT RESTORATION
273