Horton’s law of stream widths in China and its association with climate

Abstract

Study region: Nine Chinese major basins Study focus: To create a manually measured stream width dataset in the study region; To investigate the applicability and the spatial variation of Horton’s stream width-order relations where Wω̅=a×ebω). New hydrological insights for the region: We analyzed about 10,000 width measurements made from Google-earth imagery over ∼2500 rivers in nine major basins of China. The analysis suggests that:(1) when these rivers are treated as a single branching network or nine individual networks, stream order ω explains about at least 91% of the variation in average stream widths Wω̅ at the significance level of p < 0.01; (2) while the ratios of average widths of streams with consecutive Strahler orders (i.e., eb) tend to be centered at about 1.93 and vary in a narrow range of [1.50, 2.36], the values of coefficient a vary up to ∼ten folds ([0.34, 4.60]) across basins; (3) The long-term average annual precipitation volume, runoff volume, and aridity explain about 77%, 82%, and 66% of the cross-basin variation of a at the significance level of p < 0.01, respectively. These results reveal that Horton’s law of stream width holds for but varies across river networks in China and this cross-basin variability tends to be strongly associated with climate. This study may provide insights into understanding the formation of river network and estimating stream widths over data-lacking regions.

Keywords

• Stream width
• China
• Width-order relation
• River network
• Climate