Remote Sensing and Hydrodynamic Modelling to Assess Riparian Vegetation and Geomorphological Responses to Flow Regulation, Rio Chama, New Mexico, USA

ABSTRACT The alteration of the hydrological regime caused by damming remains a critical challenge for river systems. Rio Chama, a highly regulated river, has undergone severe alterations in its hydrological regime due to a series of dams that impact sediment transport mechanisms and riparian vegetation dynamics. This study employs remote sensing to assess reach‐scale changes in riparian vegetation and geomorphology and field‐informed 2D hydrodynamic modelling to determine sediment transport processes. We used a random forest classifier within Google Earth engine and high‐resolution National Agriculture Imagery Program imagery (2011–2022) to assess changes in riparian vegetation and channel planform. We evaluated the impact of different flows on sediment transport mechanisms, along with field‐data–informed sediment distribution at the sub‐reach scale. Following a 2009 high‐flow release, channel width remained relatively stable, although planform changes were observed, including shifts in the channel centre line and localised bank erosion, especially in the sinuous sections. Vegetation expanded over time and encroached along bars, linked to reduced overbank flooding and sustained base flow year‐round. Furthermore, results indicated that even smaller flows can lead to fine sediment displacement, while higher flows are necessary to mobilise coarse sediments. This study offers valuable insights for ecological flow recommendations, particularly for Rio Chama, and supports improved restoration strategies and long‐term river management in other dam‐regulated systems across arid and semi‐arid regions.