Conclusion
The instxumentadon obtained high quality floc and flow data permitting a
thorough examination of the resultant ambient aggregation conditions.
A large proportion of numerical model simulations of cohesive sediment
transport has represented Ws by a single value of the order of 0.5 mm sh
This paper has shown this value to be only truly representative of the microfloc population.
The macroflocs generally had high Ws (1-3.5 mm/s), low effective densities
(120-27 kg/m
5 ), and were ty'pically weak and highly porous (90-98%).
The importance of the macrofloc influence within the Gironde estuaty'
sedimentational regime is demonstrated by their dominance of the mass
setding flux.
Bibliographic references
Dyer K.R., Manning A.J., 1999. Observation of the size, settling velodty and
effective density of flocs, and tlieir fiactal dimensions. J. Sea Res., 41,87-95.
Christie M.C., Quartley C.P., Dyer K.R., 1997. The development of the
POST system for in situ intertidal measurements. The 7th Int. Conf. on
Elec. Eng. in Oceanogr., 23-25 June
Cont. Publ., 439, 39-45.
Eisma D., Schuhmacher T, Boekel H., Van Heerwaarden J., Franken H.,
Lann M„ Vaars A„ Eijgenraam F„ KalfJ., 1990. A camera and image
analysis system for in situ observation of flocs in natural waters. Neth.
J. Sea Res„ 27,43-56.
Fennessy M.J., Dyer K.R, Huntley D.A., 1994. INSSEV: an instrument to
measure the size and settling velocity of flocs in situ. Mar. Geok, 117,
107-117.
Kranenburg C„ 1994. 4Te fractal stmcture of cohesive sediment aggregates. Estuar. Coast. Shelf Sci., 39, 451-460.
Manning A.J., Dyer K.K, 1999. A laboratory examination of floc characteristics with regard to turbulent shearing. Mar. Geok, 160,147-170.
Manning A.J., Fennessy M.J., 1997. Inssev (In situ settling vclocity instmment) - 1.3: operator manual. Institute of Marine Studies, University of
Plymouth, 25 p.
Mehta A.J., Partheniades E„ 1975. An investigation of the depositional properties of flocculated fine sediment J. Hydrol. Res., 92(C13), 361-381.
Soulsby R.l .„ 1983. The bottom boundary layer of shelf seas. In: Physical
( Oceanography of coastal and shelf seas. Johns B. (ed.), Elsevier, New
York, 189-266.
Winterwerp J.C., 1997. A simple model for turbulence induced flocculation of cohesive sediment. 1AHR J. Hydraulic Eng., 36(3),309-326.
235
The instxumentadon obtained high quality floc and flow data permitting a
thorough examination of the resultant ambient aggregation conditions.
A large proportion of numerical model simulations of cohesive sediment
transport has represented Ws by a single value of the order of 0.5 mm sh
This paper has shown this value to be only truly representative of the microfloc population.
The macroflocs generally had high Ws (1-3.5 mm/s), low effective densities
(120-27 kg/m
5 ), and were ty'pically weak and highly porous (90-98%).
The importance of the macrofloc influence within the Gironde estuaty'
sedimentational regime is demonstrated by their dominance of the mass
setding flux.
Bibliographic references
Dyer K.R., Manning A.J., 1999. Observation of the size, settling velodty and
effective density of flocs, and tlieir fiactal dimensions. J. Sea Res., 41,87-95.
Christie M.C., Quartley C.P., Dyer K.R., 1997. The development of the
POST system for in situ intertidal measurements. The 7th Int. Conf. on
Elec. Eng. in Oceanogr., 23-25 June
Cont. Publ., 439, 39-45.
Eisma D., Schuhmacher T, Boekel H., Van Heerwaarden J., Franken H.,
Lann M„ Vaars A„ Eijgenraam F„ KalfJ., 1990. A camera and image
analysis system for in situ observation of flocs in natural waters. Neth.
J. Sea Res„ 27,43-56.
Fennessy M.J., Dyer K.R, Huntley D.A., 1994. INSSEV: an instrument to
measure the size and settling velocity of flocs in situ. Mar. Geok, 117,
107-117.
Kranenburg C„ 1994. 4Te fractal stmcture of cohesive sediment aggregates. Estuar. Coast. Shelf Sci., 39, 451-460.
Manning A.J., Dyer K.K, 1999. A laboratory examination of floc characteristics with regard to turbulent shearing. Mar. Geok, 160,147-170.
Manning A.J., Fennessy M.J., 1997. Inssev (In situ settling vclocity instmment) - 1.3: operator manual. Institute of Marine Studies, University of
Plymouth, 25 p.
Mehta A.J., Partheniades E„ 1975. An investigation of the depositional properties of flocculated fine sediment J. Hydrol. Res., 92(C13), 361-381.
Soulsby R.l .„ 1983. The bottom boundary layer of shelf seas. In: Physical
( Oceanography of coastal and shelf seas. Johns B. (ed.), Elsevier, New
York, 189-266.
Winterwerp J.C., 1997. A simple model for turbulence induced flocculation of cohesive sediment. 1AHR J. Hydraulic Eng., 36(3),309-326.
235