Above the estuary, the work for the improvement of the Paraná began in 1904 and 1905. Since 1910 the material dredged from the bed of the river has risen to 3,500,000 cubic metres a year on the average. The experience gained in the course of this work has enabled the Argentine hydrographic service to adjust its methods to the incomparable force of the river. It is impossible to maintain a general rectification of the bed and the banks, as is possible with European rivers. The only thing to do is to submit quietly to the plan which the river sketches for itself, and be content to deepen the difficult passages on the line of the main arm. Suction dredges, which work easily in the sand, attack each ridge or paso from below, making a channel into which the waters flow, so that it tends to enlarge itself up stream. The dredges are shifted from bank to bank according as the soundings tell of the formation of fresh obstacles to navigation. They were at first concentrated below Rosario, where the Argentine Government had to carry out certain engagements contracted with the Port Company; then they were scattered as far up as Santa Fé. The actual equipment suffices to carry out the programme that had been drawn up—to maintain a depth of twenty-one feet as far as Rosario and of nineteen feet as far as Santa Fé.

MAP VII.—ESTUARY OF THE RIO DE LA PLATA.

The channels of the estuary are parallel to the direction of the tidal currents, which account for their depth. Those which cross the shoals of the Playa Honda, at the bottom of the estuary, finish as no-thoroughfares, and do not give access to the southern arms of the river. From Buenos Aires ships going up the river have to go round by Martin Garcia and the mouths of the Paraná Guazu.

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As regards the section above Santa Fé, the engineer Repossini advises that, instead of adopting a programme of expensive dredging with uncertain results, they should first think of adjusting navigation to the natural conditions, and they are such as would be considered very favourable in Europe. The hydrographic service would, however, still have two functions: in the first place, the topographical study of the river and the constant placing of buoys, and, in the second place, the observation of its behaviour and anticipation of variations of level. The utility of the work of foreseeing floods, which has been carried on since 1907, has been abundantly proved. It published a daily bulletin of forecasts, based upon observation of the pluviometric scales of the upper river, which is equally valuable to the navigators and to breeders in the floodable area. It enables the breeders to get their cattle into safety before the floods come. On the other hand, the ship can, thanks to the bulletin, foretell what depth of water it will find at critical passages, and calculate exactly the load it can carry, and so complete its cargo lower down. The service of forecast of floods has morally improved navigation on the Paraná by suppressing every possible pretext for wilful stranding, which had become a current form of speculation.

Nothing is more varied than the fleet which now serves the Paraná. It includes tramps, and long, slim European ships, which load up with cereals and meat; large river boats, luxurious and light; barges and tugs, lighters and schooners, which have compensation for their slowness in their cheapness.