Human Activities Reshape Riverine Methane Hotspots: From Longitudinal Mapping to Prediction

Abstract Liu et al. (2026, https://doi.org/10.1029/2025jg009184 ) quantified longitudinal CH 4 dynamics along a 747‐km river–reservoir continuum affected by damming and urbanization. This setting reflects a broader pattern in which damming and urbanization co‐occur across large river networks, altering flow, sediment routing, and water quality in ways that can promote riverine CH 4 hotspots. The study combined dissolved‐gas and flux measurements with sediment grain size, nutrient and oxygen indicators, and methane‐cycling functional genes to identify CH 4 hotspots and their potential drivers. The authors reported higher CH 4 emissions and higher CH 4 :CO 2 emission ratios in urbanized lower reaches and reservoir‐affected reaches than in upper reaches. These patterns were linked to slower flow, the accumulation of fine sediments and nutrients, oxygen depletion, and greater methanogenic potential. Building on these findings, we argue that the next step is to improve spatial representativeness through higher‐resolution surveys of hotspot‐prone areas and to develop process‐based models that translate multi‐evidence observations into transferable predictions under different management and disturbance scenarios.