Why Should You Integrate Climate Change into Subwatershed Studies? It’s a Smarter Approach to Planning

As we experience more unpredictable and extreme weather events, it’s becoming increasingly important to integrate climate change considerations into planning and asset management practices. This is particularly true when it comes to subwatershed studies, which guide land-use decisions, water management strategies, and environmental protection efforts. Keep reading to learn how you can embed climate adaptation and mitigation strategies into these studies and make better-informed decisions to enhance resilience and reduce risks for both natural and built environments.

Understanding Natural Heritage in Subwatershed Studies

At the heart of any subwatershed study is the natural heritage system—our watercourses, woodlands, wetlands, valleylands, and other ecologically significant features and ecological functions. The natural heritage system provides essential services, from filtering stormwater and regulating temperatures, to supporting biodiversity and maintaining groundwater recharge. Protecting and enhancing natural heritage features as part of subwatershed planning is a key strategy in adapting to climate change.

Subwatershed studies (SWS) typically unfold in three phases:

• Phase 1 – Identification of Existing Conditions and Initial Impact Assessment
• Phase 2 – Completion of Impact Assessment and Development of Preferred Land Use Scenarios
• Phase 3 – Implementation and Management Strategies

For a deeper dive into this topic, check out the recent blog on watersheds by my colleagues, Holly Stemberger and Natalie Dunn.

While all three phases of a SWS are important, Phases 2 and 3 provide an opportunity to really integrate climate change adaptation and mitigation in meaningful ways.

Identifying Impacts and Opportunities

Climate change is already altering precipitation patterns, intensifying droughts, and increasing the frequency of extreme weather events. When conducting a subwatershed impact assessment, we must ask:

• How will climate change affect water availability, groundwater recharge, and drought resilience?
• Will more intense rainfall events overwhelm existing stormwater management systems?
• Are rising temperatures increasing the risk of urban heat islands?
• How can we enhance biodiversity resilience and habitat connectivity to create climate refugia?

By answering these questions, we can determine where our natural heritage features offer ecosystem services that support climate resilience by providing adaptation and mitigation benefits (I’ll discuss those more below) and where we may need to take action to bolster our resilience efforts.

The Value of Retaining Natural Heritage Features

One of the most effective strategies for mitigating climate impacts is to retain and enhance existing natural heritage features wherever possible. When we preserve forests, wetlands, and riparian buffers, we’re protecting a suite of valuable ecosystem services that support climate resilience, such as:

• Stormwater management and flood attenuation: Natural features like wetlands and forests act as sponges, absorbing excess rainfall and reducing flood risks.
• Drought mitigation and groundwater recharge: Healthy ecosystems help maintain base flows in streams and replenish groundwater supplies.
• Temperature regulation and urban heat island reduction: Trees and vegetated areas cool the surrounding environment, making cities more livable in extreme heat conditions.
• Biodiversity resilience and habitat connectivity: Natural areas serve as climate refugia, providing safe habitats for wildlife as conditions shift.
• Carbon sequestration and greenhouse gas (GHG) mitigation: Forests, wetlands, and grasslands store significant amounts of carbon, reducing atmospheric carbon dioxide (CO₂) levels and contributing to climate change mitigation.

When Habitat Removal is Necessary

While the ideal scenario is to retain natural heritage features, sometimes development necessitates their removal. But this isn’t always a negative outcome. In cases where degraded or underperforming features are removed, we can leverage this opportunity to design better-functioning landscapes.

For example, some online ponds (man-made impoundments along natural waterways) contribute to thermal loading, raising water temperatures and disrupting aquatic ecosystems. Removing these impoundments and replacing them with natural channel realignments can restore flow connectivity, reduce thermal stress, and improve conditions for fish and other aquatic species.

Compensating for Lost Natural Heritage Features

In cases where natural heritage features must be removed, thoughtful compensation strategies can ensure ecological functions are not only maintained but enhanced. Rather than simply replacing what was lost, compensation presents an opportunity to design more resilient, climate-adaptive landscapes that provide long-term environmental benefits.

For example, compensation plans should prioritize the use of native and climate-resilient vegetation by selecting plant species that are better-adapted to future projected climate conditions, such as warmer temperatures and increased drought tolerance. Additionally, when compensating hydrological features (e.g., wetlands, ricers, riparian buffers, etc.) it’s important to think about designing for future projected precipitation and extreme rainfall events. Incorporating the ecosystem services that support climate resilience that I noted above is essential in compensation planning and design.

Moving Forward: Smarter Subwatershed Planning

The integration of climate change into subwatershed studies is no longer optional—it’s essential. As municipalities, conservation authorities, and planners work to safeguard natural heritage and water resources, they must consider both the risks and opportunities presented by a changing climate.

By leveraging subwatershed studies as a tool for climate resilience, we can make more informed decisions, protect vital ecosystems, and build communities better prepared for the challenges ahead. Whether retaining natural features, enhancing degraded landscapes, or designing resilient replacements, every step we take today will shape the sustainability of our natural and built environment for future generations.

Contact me if you would like to discuss subwatershed planning further.