CHAPTER 7 ' Hydrography and Sediment Transport Characteristics of the Rio de la Plata
145
100
90
80 ,
ov
70
0\
'"
C . . 60
v
a:.
Q,
" ~ 40
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E
:>
v
~
20
10
5
10
15
Sali nity (psu)
20
1-- Playa Pascual - - Punta Brava
MONTEVIDEO
2S
30
Fig. 7.S. Salinity distribution (1981-1985) at Playa Pascual (34°45'05"S to 56°27'19"W) and at Punta
Brava (34°56'07"S to 56°09'36"W) coastal stations (from Jesus 1989)
"I was very interested by observing how slowly the waters of the sea and the river mixed, The latter, muddy and discolored, from its less specific gravity, floated on the surface of the salt water.
This was curiously exhibited in the wake of the vessel, where a line of blue water was seen mingling in little eddies, with the adjoining fluid",
De Buen (1949) refers to an oceanographic cruise aboard R.O,V, "Aspirante" carried out on 1937-1938, In 1953 he reported "a fast and successive salinity increase, with
some modest discontinuity" along a profile comprised between 34°55'S to 56°13'W and
35° 45'S to 52° 41'W,
Ottmann and Urien (1965), from a series of 10 periods of observations carried out
over a fortnight, during the years 1963-1964, aboard the lightship "Ponton Recalada"
(35°1O'S to 56°23'W), inferred the typical features of the area:
1. when Wand SE winds are greater than 10 m s-" the waters are thoroughly mixed and
high levels of salinity may be observed, the same on the surface and near the bottom;
2, when high winds are blowing from the Nand NW, a maximum layer and fresh water on the surface are found, extending in the direction of the flowing water;
3, with light wind or no wind at all, the variations in the level of salinity follow, approximately, the tide,
Nagy (1983) stated that salinity is the key variable in the Rio de la Plata, governing
hydrochemistry, suspended sediments and many biological processes, According to
Poplawsky (1983), wind effects acts on a spatial and temporal micro scale while river
runoff acts on a macroscale; salinity will be, to the first degree, a reflection of the river
runoff and, to the second degree, a reflection of the salinity evolution history,
145
100
90
80 ,
ov
70
0\
'"
C . . 60
v
a:.
Q,
" ~ 40
'5
E
:>
v
~
20
10
5
10
15
Sali nity (psu)
20
1-- Playa Pascual - - Punta Brava
MONTEVIDEO
2S
30
Fig. 7.S. Salinity distribution (1981-1985) at Playa Pascual (34°45'05"S to 56°27'19"W) and at Punta
Brava (34°56'07"S to 56°09'36"W) coastal stations (from Jesus 1989)
"I was very interested by observing how slowly the waters of the sea and the river mixed, The latter, muddy and discolored, from its less specific gravity, floated on the surface of the salt water.
This was curiously exhibited in the wake of the vessel, where a line of blue water was seen mingling in little eddies, with the adjoining fluid",
De Buen (1949) refers to an oceanographic cruise aboard R.O,V, "Aspirante" carried out on 1937-1938, In 1953 he reported "a fast and successive salinity increase, with
some modest discontinuity" along a profile comprised between 34°55'S to 56°13'W and
35° 45'S to 52° 41'W,
Ottmann and Urien (1965), from a series of 10 periods of observations carried out
over a fortnight, during the years 1963-1964, aboard the lightship "Ponton Recalada"
(35°1O'S to 56°23'W), inferred the typical features of the area:
1. when Wand SE winds are greater than 10 m s-" the waters are thoroughly mixed and
high levels of salinity may be observed, the same on the surface and near the bottom;
2, when high winds are blowing from the Nand NW, a maximum layer and fresh water on the surface are found, extending in the direction of the flowing water;
3, with light wind or no wind at all, the variations in the level of salinity follow, approximately, the tide,
Nagy (1983) stated that salinity is the key variable in the Rio de la Plata, governing
hydrochemistry, suspended sediments and many biological processes, According to
Poplawsky (1983), wind effects acts on a spatial and temporal micro scale while river
runoff acts on a macroscale; salinity will be, to the first degree, a reflection of the river
runoff and, to the second degree, a reflection of the salinity evolution history,