Sea level rise, increasingly powerful storms, and expanding coastal development have heightened the risks faced by coastal populations and ecosystems around the world. Remote sensing methods can play an increasingly powerful role in helping researchers understand risks posed by changing hydrodynamic conditions in estuarine wetlands and the coastal ocean. This dissertation applies field-based thermal infrared surface velocimetry to tidal flows in salt marsh estuaries, demonstrating this velocity measurement method’s ability to quantify complex flows of significance to coastal management and ecosystems. Chapter 1 presents a novel application of a drone-based uncooled thermal infrared sensor to measure tidal surface velocity in an estuary. The local wind speed and direction were used to calculate the wind stress at the water surface relative to the velocity measurement axis, which explained discrepancies between drone-based vs. in-channel acoustic profiler velocity measurements. Chapter 2 demonstrates the use of a cooled thermal infrared camera to measure spring tide velocities through the former dike at the mouth of the Herring River Estuary (HRE) at Cape Cod National Seashore in Massachusetts. These measurements are used to develop a stage-velocity rating curve, which can be used to estimate the volume of seawater exchanged through this restriction at a given tidal elevation providing an important baseline for post-restoration tidal exchange targets. Chapter 3 applies the same imaging method to beach overwash tidal flooding at Duck Harbor in the upper HRE, which has caused significant ecological and biogeochemical changes inland from the beach breach. Tidal velocity and depth are remotely measured from thermal infrared images to estimate flow rate through the wide, shallow overwash channel. Chapter 4 builds from the ecological impacts of tidal flooding to investigate more fundamental relationships between vegetation distribution and inundation, using statistical modeling to analyze patterns of soil moisture content and soil organic matter in ephemeral wetlands.