Rivers and streams

Abstract

The continents are crisscrossed by numerous waterways of extremely diverse lengths and flow rates. They are supplied by precipitation and are subject to constant exchanges with both the water tables via percolation through the ground and with the atmosphere via evaporation and condensation. The springs, brooks, streams, canals, rivers, and reservoirs of all sizes participate together in the water cycle. Their highly branched distribution leads hydrologic engineers to divide the land into slopes separated by watershed lines. All of these waterways impact the geography and play a major role in the economy of the bordering communities. Some of the largest or most difficult to cross have been chosen to mark the border between neighboring states. Except for rare exceptions, such as the Great Salt Lake in Utah in the United States, they are characterized by the low salinity of the water that runs through them without dwelling. We will start our tip through this gigantic network with an overview of the large rivers, with special attention paid to identifying their importance. Next we will attempt to extract some properties of the flow within these waterways, highlighting the most remarkable phenomena, such as the hydraulic jumps, meanders, and waterfalls. We shall also touch on the economic and social role of this network.

The water of the Nile loses its sweetness when it mixes with the sea.

(Egyptian proverb)