law of stream numbers

The "law of stream numbers" is part of Horton's laws of drainage composition in hydrology. These laws describe the quantitative relationships within a drainage basin's stream network. The law of stream numbers states that the quantity of streams of different orders in a drainage basin approximates an inverse geometric series. This series has a first term of unity and a ratio equal to the bifurcation ratio, which is the ratio of streams of one order to the number of streams in the next higher order. These relationships are consistent across different network patterns and demonstrate exponential relationships between stream order and other factors like length and slope.12