How stream networks pulse with rainfall

Jeff P. Prancevic and colleagues estimate that the total length of a typical US stream network is roughly five times greater in wet conditions than in dry conditions. This implies that roughly 80% of the total stream length in the US, mostly in headwater channels, runs dry for at least a few days per year. There are big differences in the variability of stream-network length across the country. Places with more variable precipitation have more variable stream networks, but topography is just as important, or more so, in controlling how much stream networks extend and retract.

A moving target

The implications are far-reaching. Other researchers have recently been chasing a cumulative measure of stream length and now Prancevic and colleagues show that they’re chasing a moving target. Understanding how stream network length varies with landscape wetness will improve estimates of greenhouse gas release from headwater channels, habitat availability, and the transport of nutrients, sediment, and contaminants. This is particularly important for predicting how streams will respond to a changing climate. And it gives us new insight into how river networks pulse when it rains.