… Understanding why some waterways form single channels, while others divide into many threads, has perplexed researchers for over a century. Geographers at UC Santa Barbara mapped the thread dynamics along 84 rivers with 36 years of global satellite imagery to determine what dictates this aspect of river behavior. “We found that rivers will develop multiple channels if they erode their banks faster than they deposit sediment on their opposing banks. This causes a channel to widen and divide over time,” said lead author Austin Chadwick, who conducted this study as a postdoctoral researcher at UCSB. The results, published in the journal Science, solve a longstanding quandary in the science of rivers. They also provide insight into natural hazards and river restoration efforts. … The formula developed by the authors enables engineers and scientists to estimate the width a restoration project will need, a deciding factor in a project’s feasibility and cost. The analysis can also help policymakers prioritize candidates for recovery.