When we talk about protecting a watershed, we tend to focus on what we can see: the rivers and streams, the salmon runs, the riparian buffers, the snowpack in the mountains. But a study published earlier this year in Water Resources Research asks us to look deeper — literally. The research, led by hydrologist Mahbod Taherian and colleagues, finds that a watershed’s sensitivity to climate variability is strongly shaped by the structure of the underground landscape — and that structure varies enormously from one watershed to the next.
The study used physics-based hydrologic modeling across real and virtual snow-dominated watersheds in North America and Europe to ask a deceptively simple question: why do some watersheds respond to a dry autumn with barely a ripple, while others swing dramatically in their behavior from year to year? The answer, it turns out, lies in the heterogeneity of subsurface permeability.
In watersheds where the underground geology is relatively uniform, snowmelt tends to follow consistent pathways regardless of how wet or dry the preceding autumn was. But in watersheds with variable subsurface structure — where permeability changes laterally through the rock and soil — the system behaves very differently. A wet autumn increases vertical connectivity underground, allowing snowmelt to infiltrate deeply and recharge groundwater stores. A dry autumn keeps that same snowmelt near the surface, routing it quickly into streams. The result is a system that amplifies climate variability rather than absorbing it.
What makes this research so significant for watershed advocates is what it reveals about vulnerability. Two watersheds might look nearly identical on a topographic map and receive the same annual precipitation, yet one may be far more exposed to the consequences of a drying climate than the other — not because of what’s on the surface, but because of what’s below. As the researchers note, understanding these hidden controls offers water managers and policymakers a roadmap for identifying which watersheds face the greatest risk in a changing climate.
For those of us working from a rights-of-nature framework, this research carries a deeper resonance. The watersheds most vulnerable to climate disruption are often those that lack the institutional voice to demand protection. A river system does not file comments on a water management plan. A snowmelt-fed aquifer does not appear as a party in an adjudication. The legal and regulatory structures we have built treat water primarily as a resource to be allocated — and they are poorly designed to account for the dynamic, subsurface processes that determine whether a watershed can sustain itself through drought, flood, and the compounding stresses of a warming world.
Understanding the physics of watershed sensitivity is necessary but not sufficient. Alongside better science, we need legal frameworks that recognize watersheds as integrated living systems — systems whose health depends not only on how much water enters from the sky, but on the pathways that water follows through soil and stone, and the deep reserves it builds up over time. The more we learn about how these systems actually work, the clearer it becomes that protecting them requires more than surface-level thinking.
Read the article The hidden physics of watersheds: Why some are more sensitive to climate variability than others, by Ali Ameli, Phys.org, January 26, 2026.
Standing for Nature is a Washington State nonprofit dedicated to protecting watersheds and ecosystems through legal advocacy, community engagement, and strategic litigation. Our work is grounded in the principle that natural systems have inherent rights worthy of legal recognition.
