Other significant changes are observed in the upper segment of the
central estuaty and in the lower course of the Garonne and Dordogne
rivers. Nowadays, these areas seem to be covered with c(>arse sand and
gravel. This seems to be the result of continuous dredging rather than
the effect of a longer stay of the turbidity maximum in the downstream
parts of the funnel-like estuaty.
Conclusion
The sedimentological patterns of the Gironde estuary have been identified
and appear to be typical of mixed wave- and tide-dominated estuaries. The
marine sediment exteneis approximately 20 km upstream from the
Pointe de Suzac and forms a compact sandy tongue which is in contact
with the massive estuarine mud of the lower part of the funnel. This
transition zone is being shifted because the intensity of main hydrodynamic factors (i.e. waves, tides, river discharge and turbidity maximum)
changes from time to time. Strengthening of the fluvial processes in the
last 30 \ears is likely to contribute greatlv to the cover of the upper estuary with coarser sediment.
In general, all the above disparities observed on the compared sedimentological maps could be attributed to the interaction between marine
and fluvial processes as well as human interference, which change in
strength, in space (along the estuary) and in time (daily, seasonally, annually, etc.).
Bibliographic references
Allen G.P., 1972. Etude des processus sédimentaires dans l’estuaire de la
Gironde. Thèse de doctorat, université de Bordeaux 1, n° 353, 314 p.
Castaing P., 1981. lo transfert à l’océan des particules estuariennes : cas
de la Gironde. Thèse dT.tat, université de Bordeaux 1, n° 701, 530 p.
Jouanneau J.M., Latouche C., 1981. The Gironde Estuary. E. Schw.
Verlag, Stuttgart, 115 p.
Kaipsimalis V., Tastet J.-P., Massé L., 2000. Modern sedimentology of
macrotidal estuaries: the example of the Gironde (SW France). 6th
Hellenic Symposium on Oceanography and Fishery, Chios, vol. I,
528-532.
222
central estuaty and in the lower course of the Garonne and Dordogne
rivers. Nowadays, these areas seem to be covered with c(>arse sand and
gravel. This seems to be the result of continuous dredging rather than
the effect of a longer stay of the turbidity maximum in the downstream
parts of the funnel-like estuaty.
Conclusion
The sedimentological patterns of the Gironde estuary have been identified
and appear to be typical of mixed wave- and tide-dominated estuaries. The
marine sediment exteneis approximately 20 km upstream from the
Pointe de Suzac and forms a compact sandy tongue which is in contact
with the massive estuarine mud of the lower part of the funnel. This
transition zone is being shifted because the intensity of main hydrodynamic factors (i.e. waves, tides, river discharge and turbidity maximum)
changes from time to time. Strengthening of the fluvial processes in the
last 30 \ears is likely to contribute greatlv to the cover of the upper estuary with coarser sediment.
In general, all the above disparities observed on the compared sedimentological maps could be attributed to the interaction between marine
and fluvial processes as well as human interference, which change in
strength, in space (along the estuary) and in time (daily, seasonally, annually, etc.).
Bibliographic references
Allen G.P., 1972. Etude des processus sédimentaires dans l’estuaire de la
Gironde. Thèse de doctorat, université de Bordeaux 1, n° 353, 314 p.
Castaing P., 1981. lo transfert à l’océan des particules estuariennes : cas
de la Gironde. Thèse dT.tat, université de Bordeaux 1, n° 701, 530 p.
Jouanneau J.M., Latouche C., 1981. The Gironde Estuary. E. Schw.
Verlag, Stuttgart, 115 p.
Kaipsimalis V., Tastet J.-P., Massé L., 2000. Modern sedimentology of
macrotidal estuaries: the example of the Gironde (SW France). 6th
Hellenic Symposium on Oceanography and Fishery, Chios, vol. I,
528-532.
222