In regard to the hydrographic system of the country, we may divide it into four systems: the system formed by the rivers within the Plata basin; the central system, the Patagonian system formed by the basins of the rivers flow ing from the eastern slope of the Andes, and lastly, the system of the province of Buenos Aires.
The basin of the Plata, which includes most of the territory of Argentina and part of those of Brazil, Uruguay and Paraguay, is drained by the river Plata, justly considered as the en trance gate to South America; the rivers Uru guay and Parana which debouch into the Plata after a course of 900 miles in the first case and of 2,000 in the second; the river Paraguay, which forms the axis of the system and joins the Parana. at 1,200 miles from its source; the Pilcomayo and Bermejo rivers which rise in Bolivia and fall into the Paraguay after having crossed the territory of the Chaco; the Salado del Norte River which runs through the provinces of Santiago del Estero and Santa Fe to discharge into the Parana near the city of Santa Fe; the river Carcarafia, another affluent of the Parana formed by the union of the Tercero and Cuarto riders which have their sources in the Cordoba range; and in addition other rivers of less importance, all of which rise in the province of Buenos Aires and are affluents of the river Parana and the river Plata.
Mr. E. L. Corthell, an American engineer, says that ((the Parana has a larger discharge than the Mississippi; its annual flow is double that of the Ganges, three times that of the Saint Lawrence, four times that of the Danube and five times that of the Nile. There are records of 608 cubic miles in one year? The Parana River is one of South America's great water ways. Transatlantic steamers of 10,000 tons drawing 23 feet can enter the river up to Ro sario, 240 miles from Buenos Aires. Those of 6,000 tons can reach the ports of Parana and Colastine. Specially constructed vessels can go farther, to Corrientes, 640 miles above Buenos Aires. At Corrientes the Paraguay River flows into the Parana which at this point makes a sharp turn toward the south. From the point of view of navigation the Paraguay River is a natural continuance of the Parana. Steamers
drawing 13 feet ply from Buenos Aires or Cor rientes to Asuncion, on the Paraguay River, during nine months of the year.
The upper Parana, from Corrientes toward the east, is navigable by large boats only to the falls of Apipe, 145 miles above Corrientes. But smaller steamers ply regularly beyond Apipe up to Posadas and still smaller craft up to near Iguaza Falls, on the boundary line be tween Argentina, Paraguay and Brazil.
The river Uruguay is navigable by large steamers up to Concordia which is an import ant agricultural and commercial centre. But during the floods the river is everywhere navi gable. These floods are quite sudden but not long continued. The floods of the Parana are much longer continued, because its source is in the tropical and rainy regions of Brazil and it receives also, through the Paraguay, the waters from the flanks of the Andes. At the conflu ence of the latter river with the Parana at Corrientes, the rise of the floods is about 33 feet; at Rosario it is from 19.7 to 23.5 feet.
Of the other rivers belonging naturally to the Plata system, such as the Pilcomayo, the Bermejo and the Salado, none at present is of economic importance. Further south the Parana River receives the Carcarafia, formed by the confluence of the Tercero and Cuarto rivers which drain the southeastern part of Cordoba. These rivers are used for irrigation purposes and the Argentine government has entered into an extensive program of irri gation works contemplating the reclamation of large tracts of land along the valleys of these rivers and also of the Quinto, which more properly belongs to the central system.
The central hydrographic basin is formed by a vast depression that in its lowest part is occupied by the lakes of Porongos and Mar Chiquita into which several rivers such as the Dulce and the Primero and Segundo fall. Irri gation works in these rivers have been going forward on a large scale. The Rio Primero dam holds 260,000,000 cubic metres and the Segundo River dam 350,000,000 cubic metres.