Interbasin and Intrabasin Competitions Control Drainage Network Density

Abstract

The growth and evolution of drainage networks are controlled by erosional and depositional processes forced by climate and tectonics operating on the landscape. By analyzing the data from 137 natural basins across the United States and an ensemble of synthetic terrains generated by a numerical landscape evolution model, we observed a power law relationship between the characteristic length (the length scale at which the timescales of diffusive and advective transports are equal) and drainage density (total channel length divided by drainage area) with two scaling regimes. The observed regimes exhibit significantly different characteristics in terms of intrabasin (i.e., the interaction between channels and hillslopes) and interbasin (i.e., the interaction between adjacent basins) competitions. Our findings reveal the relationship between drainage density and basic geomorphic and topologic characteristics, which encapsulate the advective and diffusive transport processes acting on the landscape.