This dissertation advances high-spatial-resolution satellite remote sensing to quantify suspended sediment dynamics, map blue carbon in salt marshes, and assess marsh resilience to sea level rise (SLR). Together, these studies link fine-scale sediment processes to coastal ecosystem stability and carbon storage. In Chapter 2, I develop a particle composition–adaptive algorithm for retrieving suspended particulate matter (SPM) from ocean remote-sensing reflectance, applicable to most land- observing satellites. Using over 800 paired in situ spectral and SPM measurements from 12 global sites, the method classifies waters as organic-rich, mineral-rich, or extremely mineral-rich based on remotely derived particulate organic carbon/SPM ratios, then applies composition-specific retrievals. Implemented on the 40-year Landsat archive in Google Earth Engine, the algorithm outperforms eight existing methods and enables global, fine- scale mapping of seasonal and long-term SPM patterns. Chapter 3 applies temporally optimized Landsat and Sentinel-2 imagery (1984–2022) to map soil organic carbon (SOC) in Northeast US salt marshes, using 410 soil samples from 15 sites. Results show that remote sensing indices, timed to high tide and vegetation phenology specific to geomorphic setting, effectively capture SOC variability. Incorporating tidal range improves predictions in barrier marshes, while sediment supply improves predictions in fluvial marshes, highlighting the need for geomorphically tailored models. In Chapter 4, I use the high-resolution suspended sediment product to evaluate marine- sourced sediment’s role in supporting tidal marsh resilience across 103 sites in the Northeastern US. Vulnerability, assessed with the unvegetated-to-vegetated ratio (UVVR) and relative marsh elevation (Z*), reveals resilience thresholds (SSC > 20 mg/L; RSLR < 5.2 mm yr−1). Marshes meeting either threshold tend to persist, whereas those with low SSC and high RSLR are more vulnerable. A pronounced north–south gradient shows higher vulnerability in the south, driven by greater SSC declines. Collectively, these studies demonstrate that high-resolution satellite can bridge understanding from particle dynamics to marsh-scale carbon storage and vulnerability, providing critical tools for coastal monitoring, restoration, and climate adaptation planning.