Plain Language Summary
Rainfall in mountain landscapes often varies with elevation; a pattern known as orographic rainfall. Rivers that sculpt these landscapes rely on rainfall for their erosive power, where more rainfall typically means greater erosive power. Rainfall also affects how steep these rivers are, which in turn affects the steepness of the topography around them. Here, we investigate how concentrating rainfall at higher and lower elevations – representing two common orographic rainfall patterns that may be enhanced or relaxed by climate change – influences the steepness mountain rivers, erosion patterns, and thus the evolution of mountain topography. We show that these orographic rainfall patterns complicate simple expected relationships among metrics commonly used to quantify the role of rainfall (and more broadly climate) on the topography of mountain landscapes. Further, we show that rivers respond in unexpected ways to changes in orographic rainfall patterns, as would occur following a change in climate, suggesting that common wisdom about how rivers and mountain landscapes respond to changing climates is incomplete.