Abstract Quantifying decadal‐scale erosion rates in tectonically active regions is essential for assessing landscape hazards and constraining sediment budgets. A key question in Earth surface processes is how contemporary erosion measurements influenced by recent climatic extremes relate to long‐term geological rates. This study investigates this relationship by evaluating two decades of topographic change (2000–2020) in Taiwan's Laonong River Basin (1,373 km 2 ), a mountainous landscape characterized by active landslides, steep relief, and intense rainfall, including Typhoon Morakot in 2009, the highest‐rainfall typhoon on record in Taiwan. Several satellite‐derived digital elevation models (DEMs) were benchmarked against high‐resolution LiDAR to identify the most suitable data set for long‐term change detection. The reprocessed SRTM NASADEM was identified as the optimal DEM due to minimal artifacts and limited void filling, with further improvement achieved through canopy removal and frequency‐domain bias correction. DEM differencing across sub‐catchments revealed that erosion rates averaged ∼15.3 mm/yr, reaching ∼551 mm/yr in landslide‐affected tributaries. However, approximately 87.6% of the eroded material was stored within the basin, predominantly in valley‐fill deposits, reducing effective net lowering across the basin to 5.06 ± 1.60 mm/yr. This rate is consistent with long‐term (10 3 –10 6 yr) cosmogenic and thermochronological estimates (∼3–6 mm/yr), indicating that sediment buffering spatially averages extreme localized erosion over decadal timescales. These findings highlight the role of internal sediment storage in shaping basin‐scale erosion patterns and emphasize the importance of high‐resolution erosion assessments for capturing geomorphic heterogeneity. The results also demonstrate the potential of underutilized global DEMs, once corrected, to resolve meaningful geomorphic signals in mountainous terrain.
Kumar et al. (Fri,) studied this question.