536
J. Ojeda Zújar et al.
LOW TIDE
In the first principal component taken from all the low tide images (Fig. 6) three water
masses can be identified in the estuary in order of increasing turbidity, apart from the
cleaner sea waters outside the estuary.
the external water mass of medium turbidity originated from mixing of the
turbid estuarine waters with clear coastal water. This water mass occupies a
wide zone parallel to the coastline and widens at the outlets of the principal
and Punta Umbría channels, marking the maximum extent of the
corresponding turbidity plumes
a medium-high turbidity water mass located in a narrow zone anchored to the
coastline, the final reaches of the Padre Santo channel, all of the Burro and
Punta Umbría channels, and the middle reaches of the Odiel. This last drains
more easily than the Tinto, displacing the turbidity maximum downstream
towards the main channel. Clearly distinguishable is the turbidity plume
generated by the Punta Umbría channel, much more so than in the case of the
main channel
the highest turbidity is found in the water mass which occupies the lower
reaches of the Odiel channel, the whole of the Tinto channel, and much of the
Padre Santo channel. Because the turbid Odiel waters drain early they arrive
at the Padre Santo channel, concentrate the maximum turbidity in this zone,
and link up with the waters from the Tinto channel which arrive later because
of the Tinto channel's lesser transverse section and its non-alignment with the
main channel
The distribution of the water masses mentioned so far can be considered
representative of the situation at low tide because the ebb currents continue to flow for
over two hours after the theoretical low tide point. However, if one considers the tidal
phase of the images in this low-tide group, as seen in table 1, it is clear that there are
two very distinct groups; two images only 17 and 19 minutes after theoretical low tide,
J. Ojeda Zújar et al.
LOW TIDE
In the first principal component taken from all the low tide images (Fig. 6) three water
masses can be identified in the estuary in order of increasing turbidity, apart from the
cleaner sea waters outside the estuary.
the external water mass of medium turbidity originated from mixing of the
turbid estuarine waters with clear coastal water. This water mass occupies a
wide zone parallel to the coastline and widens at the outlets of the principal
and Punta Umbría channels, marking the maximum extent of the
corresponding turbidity plumes
a medium-high turbidity water mass located in a narrow zone anchored to the
coastline, the final reaches of the Padre Santo channel, all of the Burro and
Punta Umbría channels, and the middle reaches of the Odiel. This last drains
more easily than the Tinto, displacing the turbidity maximum downstream
towards the main channel. Clearly distinguishable is the turbidity plume
generated by the Punta Umbría channel, much more so than in the case of the
main channel
the highest turbidity is found in the water mass which occupies the lower
reaches of the Odiel channel, the whole of the Tinto channel, and much of the
Padre Santo channel. Because the turbid Odiel waters drain early they arrive
at the Padre Santo channel, concentrate the maximum turbidity in this zone,
and link up with the waters from the Tinto channel which arrive later because
of the Tinto channel's lesser transverse section and its non-alignment with the
main channel
The distribution of the water masses mentioned so far can be considered
representative of the situation at low tide because the ebb currents continue to flow for
over two hours after the theoretical low tide point. However, if one considers the tidal
phase of the images in this low-tide group, as seen in table 1, it is clear that there are
two very distinct groups; two images only 17 and 19 minutes after theoretical low tide,