WATER-RESOURCES, SALINITY AND SALT YIELDS OF THE RIVERS OF THE BOLIVIAN AMAZON

The average dissolved content of the Madera, Beni and Mamore Rivers, 57-61 mg l** minus **1 respectively, is relatively low to medium. Many types of water, classified according to their ionic compositions, have been characterized in the Andes, the Amazon Plain, and in the main drainage axis. The slightly mineralized black water of the plain seems the most unique type. Recycling of water vapor in the Amazon Basin is confirmed by the low chloride and sodium contents of the water in the plain. Thus the importance of this phenomena in the genesis of rainfall throughout the basin is emphasized. The contribution of the Upper Madera River to the Amazon River is 9. 7% of the water and 10. 9 percent of ionic load.