Characterization according to size of fluvial drag sediments in the bed of the Encañada River - Cajamarca – Peru

Abstract

This research addressed the analysis of sediment concentration variation in the bed of the Encañada River, Cajamarca-Peru, through the selection and excavation of ten analysis points with their respective test pits. Processes were carried out both in the field and in the soil laboratory. Initially, test pits measuring 0.80 m by 0.80 m by 0.80 m were constructed, with weights extracted based on the diameter of the present solids, ranging from sands and gravels to large and small pebbles, as well as small stones. Subsequently, 6 kg samples were taken from each test pit for laboratory granulometric analysis. The results indicated an initial equilibrium in sediment variation, starting from test pit 1 with 27.20% of small stones, decreasing to a minimum of 2.12% in test pit 6. From this point, the concentration increased again, reaching its peak in test pit 9 with 33.91% and remaining elevated in test pit 10 with 27.55%. It was concluded that the variation in sediment concentration in the Encañada River does not show a correlation with altitude. Additionally, it was highlighted that the predominant material in the riverbed was gravels and sands, while small pebbles represented the lowest concentration percentages.