Heejun Chang

Increasing stream temperatures resulting from climate change and consequent detrimental impacts on temperature‐dependent aquatic species have signalled the need to better understand how different streams respond to changes in air temperature. This research generates a new assessment of thermal sensitivity in the Clackamas River Basin, Oregon, USA by analysing how underlying geology, climate, hydrology and land cover explain spatial variation in stream thermal sensitivity. Multiple linear regression analysis using spatially explicit landscape predictors across 72 sites identified upstream High Cascades geology, elevation, baseflow index, total upstream area and upstream shrubland area as the most significant and stable predictors determining thermal sensitivity. Spatial stream network and random forest models further validated and clarified spatial influences on stream temperature and each improved performance relative to multiple linear regression. Predictors derived at the total upstream area scale were most consistently associated with thermal sensitivity when compared to local reach contributing area or 100‐m wide buffer area scales. Streams underlain by High Cascades geology, with higher baseflow and greater upstream area were substantially less sensitive to air‐temperature changes ( β = −0.27 to −0.61). Meanwhile, higher elevation ( β = −0.51 to −0.59) and lower shrubland cover ( β = 0.19 to 0.30) were associated with lower thermal sensitivity. Variation in predictors retained among models appears to reflect different indicators of shared underlying processes. Furthermore, this study confirms that these predictors are statistically robust drivers of stream thermal sensitivity via regularized regression techniques. Analysing why streams are more or less climate‐resilient can inform management and restoration efforts and protect cold‐water habitats.

In early 2025, the American Association of Geographers (AAG) council approved a proposal led by one of the editors (Chen) of The Professional Geographer for both editors to create an article collec...

Most research into post-fire geomorphology has been conducted in regions with frequent fire, such as in dry Mediterranean and temperate climates and less has been conducted in wet forests where wildfire is now expanding with climate change. Because climate, soils, topography, vegetation, management legacies and fire history influence post-fire geomorphic processes, research into post-fire erosion and debris flow hazards across a broader set of climatologies is needed. The western Pacific Northwest (wPNW) of the United States is susceptible to multiple types of post-fire debris flows (i.e. shallow landslide-initiated and runoff-generated) that can be initiated by longer-duration lower-intensity rainfall compared to other regions in the western US. Therefore, knowledge of how wildfire impacts geomorphic processes in drier, more frequently burned regions does not necessarily apply to the wetter wPNW climate. Significant gaps in data coverage remain a key limitation for predictive modeling and empirical studies in this region. This review synthesizes the current state of post-fire geomorphic knowledge and identifies gaps in data and understanding for the wPNW. These gaps and opportunities for future work can help expand knowledge and evaluate assumptions about post-fire geomorphology in other regions, such as those with similar pyro-climatology and others not yet well represented by current post-fire geomorphology research.

An increase in the occurrence of large, high severity wildfires in the western Pacific Northwest (PNW), USA, has created an urgent need for science to better inform forest management and policy decisions to maintain source water quality in the region. The western PNW faces similar challenges to other regions with shifting wildfire regimes and large population centers reliant on surface water from forested catchments. However, the uniquely wet and highly seasonal climate of the western PNW suggests that findings from other, more frequently burned regions may not be directly applicable. To identify science, monitoring, and management gaps and opportunities in the western PNW, this review was collaboratively undertaken by academics, non-government and industry representatives, and local, state, and federal government entities who have been working together since the 2020 Labor Day fires in Oregon. Focusing on Oregon and Washington, we found that monitoring networks for continuous water quantity and quality cover much of the state with greater representation in western U.S. ecoregions, but few studies have analyzed and published these data to capture and communicate the post-wildfire response. Approximately half of the streamgages in Oregon and Washington record major water quality parameters, and hundreds of sites in the area have discrete sampling for a wide range of water quality constituents. Still, numerous gaps exist in understanding the short- and long-term impacts of wildfire on hydrology, water chemistry, including pH and dissolved oxygen, mobilization of metals, aquatic ecosystems, and downstream drinking water treatment. Collective action to further collect, analyze, interpret, and publish the key data could help improve our understanding of post-wildfire water quality impacts in this and other increasingly wildfire-affected regions.

Urban beavers provide ecological benefits, yet their presence in cities can generate visible tensions related to flooding, infrastructure, and land use. This study examined how perceptions of beaver impacts, endorsement of management practices, ecological knowledge of beavers, and legal protection preferences varied across sociodemographic and spatial factors at three sites along an urbanisation gradient using a voluntary survey of 180 respondents. Overall sentiment toward beavers varied significantly by site context and length of residence. Respondents at the peri-urban site (37.3% developed land cover) reported more positive perceptions than those at the urban site (96.5% developed land cover). Respondents who had resided in the area for at least five years also reported more positive sentiment than those who had resided there for less than five years. In contrast, simple distance measures to water or green space were not associated with overall perceptions. Support for coexistence-enabling practices was generally high, whereas endorsement of beaver-limiting strategies was comparatively lower. Liberals had substantially lower odds of selecting beaver-limiting strategies than conservatives. Preferences for strong legal protection increased sharply with more positive overall perception, while ecological knowledge and management endorsement did not independently predict legal protection. Open-ended responses also reflected the urbanisation gradient across sites. Flooding and infrastructure concerns were raised most frequently at the urban site, while ecological benefits were more frequently noted at the peri-urban and the wildlife refuge site. These findings suggest that affect, political orientation, and experiential landscape context, rather than proximity alone, structure public perceptions toward urban beavers.

This study investigates the effects of socioeconomic characteristics, density, built environment, and urban spatial structure on vehicle miles traveled (VMT) across 461 urbanized areas in the United States. Using multiple regression models, we compare the explanatory power of conventional variables with those representing the spatial distribution of major urban elements, such as population, employment, land use, and travel demand to city centers. The results show that population-weighted distance to the city center and the contiguity of high-intensity land use significantly influence vehicle travel, with greater distances from city centers and more fragmented land use leading to higher VMT. Models incorporating urban spatial structure variables exhibit improved explanatory power and better fit than those including only socioeconomic, density, and built environment variables. These findings demonstrate that urban spatial structure captures key aspects of vehicle travel behavior that are overlooked by traditional measures. Policy implications include the promotion of compact, mixed-use development, infill and brownfield redevelopment, and urban growth boundaries to reduce vehicle dependence. The study highlights the importance of spatial planning in managing urban travel demand and offers a refined analytical framework for examining the interplay between urban form and mobility.

Over the past 30 years, the City of Portland, Oregon, USA, has emerged as a national leader in green stormwater infrastructure (GSI). The initial impetus for implementing sustainable stormwater infrastructure in Portland stemmed from concerns about flooding and water quality in the city’s two major rivers, the Columbia and the Willamette. Heavy rainfall often led to combined sewer overflows, significantly polluting these waterways. A partial solution was the construction of “The Big Pipe” project, a large-scale stormwater containment system designed to filter and regulate overflow. However, Portland has taken a more comprehensive and long-term approach by integrating sustainable stormwater management into urban planning. Over the past three decades, the city has successfully implemented GSI to mitigate these challenges. Low-impact development strategies, such as bioswales, green streets, and permeable surfaces, have been widely adopted in streetscapes, pathways, and parking areas, enhancing both environmental resilience and urban livability. This perspective highlights the history of the implementation of Portland’s GSI programs, current design and performance standards, and challenges and lessons learned throughout Portland’s recent history. Innovative approaches to managing runoff have not only improved stormwater control but also enhanced green spaces and contributed to the city’s overall climate resilience while addressing economic well-being and social equity. Portland’s success is a result of strong policy support, effective integration of green and gray infrastructure, and active community involvement. As climate change intensifies, cities need holistic, adaptive, and community-centered approaches to urban stormwater management. Portland’s experience offers valuable insights for cities seeking to expand their GSI amid growing concerns about climate resilience, equity, and aging infrastructure.