Nine ways we can future‑proof rivers against extreme events

How we can protect river biodiversity from the increasing threat of extreme floods, droughts and heatwaves

River flows in the Willamette River, Salem, Oregon, not far from where we lived for 3 years while working at Oregon State University in Corvallis. Note the striking difference between flows to last week’s river — the Yampa in Colorado. Last week, snowmelt dominated the signal, this week, winter rains do. The more extreme high-flow years are noted by the increasingly yellow lines.

Last week we looked at how extreme events like floods, droughts and heatwaves are reshaping river biodiversity. This week is the practical half of the story: what we can actually do to strengthen rivers before the next flood, drought or heatwave hits.

Climate extremes aren’t going away, and rivers aren’t guaranteed to rebound. They’re not only pushing rivers to their limits, they’re also testing the limits of our scientific knowledge. Rolling out effective, durable solutions is not straightforward. But the evidence we do have points toward a clear set of levers worth paying attention to.

In going through this process in our recent synthesis¹, one theme kept emerging: the future of river biodiversity depends on shifting from local, reactive interventions to catchment-scale, resilience-focused approaches.

Here are nine ways we can future‑proof rivers against an increasingly extreme climate.

1. Restore natural flow and temperature variability

Natural, variable, and seasonally dynamic flows underpin resilience of river biodiversity. Dampened or highly regulated flows reduce a system’s ability to absorb and recover from extremes, and tend to simplify the assemblages of species that depend on them. This is obviously problematic as diversity begets resilience in ecosystems. The science of flow restoration has come a long way, enabling well-timed releases that can promote spawning of fish, transport seeds, control sediment, and keep invasive species in check.

2. Protect and enhance refuges

Deep pools, permanently flowing reaches, groundwater upwelling zones, and off‑channel habitats are critical for resistance to and recovery from extremes. Each provide species places to hunker down during heatwaves and drought or recolonise from following a flood. And when natural refuges are gone, engineered thermal refuges, such as via cool-water releases, shaded artificial pools, and groundwater pumping, may help buy time.

3. Reconnect fragmented river networks

Connectivity is essential for recovery. Barriers that block recolonisation after extremes slow or prevent recovery. Removing or modifying culverts, weirs, and dams help restore the movement pathways species rely on. It’s not all one way though. In some cases, adding artificial barriers may help protect threatened species from the combined pressures of invasive species and increasing extremes. Rivers are, after all, both naturally highly connected systems but also isolated within a sea of land. The natural branching nature of rivers is fundamental for resilience of their species. While it helps spread the impacts of extremes, it also enables species to recolonise impacted areas.

In your system, does this feel realistic — or completely out of reach?

4. Prioritise Nature-based Solutions: let rivers roam free

Reconnecting rivers to their floodplains, rebuilding riparian forests, and giving rivers the room they need to move all reduce fragility. Locking rivers into confined channels increases it — The Netherlands learned this lesson and moved on. Rivers with more room comprise more diverse habitat, species, refuges, and greater connectivity to healthy riparian ecosystems, which help to reduce thermal stress, stabilise banks, and feed aquatic organisms. This requires a framing shift from “command-and-control” to “living with water”.

5. Reduce underlying stressors that amplify extremes

Intensive land use, nutrient enrichment, and water extraction amplify extreme event impacts. Rather than band-aid solutions, managing these pressures at their source increases a system’s ability to cope with extremes. Monocultures of any kind promote fragility, whereas mixed, multifunctional landscapes provide rivers the diversity and buffering capacity they need to cope with shocks.

6. Identify and protect high‑resilience catchments

Proactively managing rivers for risks from extremes starts with knowing where resilience is still possible. Catchments differ enormously in their capacity to support biodiversity and absorb shocks. From free-flowing headwaters to heavily modified systems with limited recovery potential, recognising this variation helps prioritise where efforts will pay off. The typology in our paper helps identify which catchments can still provide resilience at different spatial scales, and where management efforts will have the greatest return.

Table 1 from our paper.

7. Use frameworks that help prioritise decisions

Once we know what we’re dealing with, we still need to decide what to do. The Resist–Accept–Direct (RAD) framework helps managers decide when to protect current states, accept unavoidable change, or steer ecosystems toward new states. RAD is especially powerful when paired with catchment‑scale assessments as it helps match the type of intervention to a system’s resilience potential (see point 6).

8. Implement anticipatory, catchment‑scale planning

We know that ecosystems exist within larger, interconnected systems: species, energy, water, nutrients all flow in and out constantly. So instead of reacting to extremes on a site-by-site basis, managers need to think of rivers as connected meta-systems — linking refuges, restoring keystone habitats, protecting source populations, and thinking of the whole catchment and beyond. But this requires knowledge of the system — so long-term datasets are key. So too are high-frequency data. Managing responses to extremes requires knowing how they work and modern technology is beginning to make this easier (e.g. high‑frequency sensors, eDNA, remote sensing etc.).

9. Anticipate the future with models

Of course, we need to go into the future eyes open. Computer modelling helps us do that. Iterative forecasting, where models are set up to update regularly as new data is captured can help to inform adaptive management approaches in real time. Beyond near-term forecasts, it’s imperative we explore the range of possible longer-term outcomes of extreme impacts on river biodiversity so we can adequately prepare.

There’s a lot going on here, so don’t worry about the details. But the point I want to make is that monitoring and modelling can work together to better understand extremes. Figure 5 from our paper.

What the future holds is highly uncertain. But we know this — it’s likely to be more extreme. Rivers and their biodiversity will bear much of the brunt of a more extreme future. It’s imperative we shift from being reactionary at local scales to building resilience at catchment scales.

These nine points are far from exhaustive, but they’re among the most consistent, evidence-backed tools we have.

Your turn! I’d love to hear what you’d add, challenge or expand. 👇👇

I’m especially interested in how these levers play out in different river systems. If one of them resonated — or felt impossible — I’d love to hear why in the comments.

1. Tonkin, J. D., T. Siqueira, J. Merder, T. Datry, N. L. Poff, J. Talbot-Jones, and J. D. Olden. 2026. Extreme events and river biodiversity under climate change. Nature Reviews Biodiversity. DOI: 10.1038/s44358-026-00131-7