ABSTRACT
This methodology was part of a research on sediment bedload, and it was used to estimate the threshold of the incipient motion of particles between gravel to boulder, in five reaches of the Grande de Terraba River catchment in Costa Rica. The methodology consists in the demarcation and observation of sediment particles before and after a peak flow. The sites studied were located in sediment bars near a hydrologic station in order to have a record of the peak flow that promotes the movement. The grain size of the sediment analyzed have a D50 from 16 to 130 mm and the period studied was the rainy season of 2014. From the results it was possible to characterize the threshold of the incipient motion and to identify how the particles of sediment bed load moved in the catchment.
