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Purpose: Erosion and its spatial distribution in three agricultural headwater catchments were assessed in the border of the volcanic plateau in Southern Brazil. We analyzed terrain, hydrological processes, and land use influence to provide a comprehensive assessment of the catchments' sensitivity to erosion. Methods: Topographic attributes were acquired from a digital elevation map, WaterSed model was parameterized to simulate runoff, diffuse erosion, and sediment yield, and sediment source contributions were estimated using sediment fingerprinting based on near-infrared spectroscopy. Results: According to the modeled results, areas covered by crop fields, grasslands, and those adjacent to the drainage network are the most sensitive to erosion. Short distances from the source to the river network and the occurrence of high magnitude rainfall events (80 mm) promoted increases in connectivity for runoff/sediment transfer. Erosion simulations show that areas of low infiltration, such as unpaved roads, were important runoff generators during lower volume rainfall events (25 mm). Sediment fingerprinting provided satisfactory results to quantify the contributions of unpaved roads to sediment (~ 39%). Topsoil and stream channels were also significant sediment sources for the set of analyzed samples, corresponding to average contributions of 38 and 23%, respectively. Conclusion: Areas sharing geomorphological similarities did not lead to similar sediment contributions. Vegetation cover controlled erosion in topographically sensitive areas. Unpaved roads provide a significant sediment source, followed by topsoil and stream channels. The complementary results provide useful insights to better coordinate planning environmental conservation strategies in these fragile landscapes. [ABSTRACT FROM AUTHOR]

Purpose: Soil degradation is a widespread problem and currently one of the biggest challenges in modern-day agriculture. The partial adoption of conservation agriculture, such as no-till management, does not provide adequate erosion control, and the hydrology dynamics on hillslopes under no-till management remain poorly quantified. This study examines the hydrology of agricultural hillslopes under no-till management, with and without terraces in southern Brazil.Materials and methods: Water and soil losses were measured in two paired, zero-order catchments (2.4 ha) under no-till cultivation, with and without broad-based retention terraces. Rainfall, surface runoff, and suspended sediment concentrations were monitored during major rainfall events. Analysis of hydrographs and sedigraphs was used to derive the peak flow, runoff duration, and sediment yield values and the hysteresis between surface runoff and the suspended sediment concentration during different seasons.Results and discussion: The results show higher soil and water losses in the catchment without terraces. Terracing reduced peak flow rates by 79%, sediment yield from 0.44 to 0.16 t ha−1, and the total surface runoff from 3943 (126 mm) to 855 m3 (36 mm) during 31 events over 16 months. The no-till system without terraces was unable to adequately control surface runoff and soil erosion. Surface runoff and sediment yield were higher under no-till without terraces than under no-till with terraces.Conclusions: The difference in terms of surface runoff volume and sediment yield indicates an important difference in the hydrology and soil erosion in the catchment without terraces, which is represented by high-surface-runoff coefficient values observed during the rainfall-runoff events. The short lag time and steep rising limb of the hydrographs indicate high-surface-runoff responsivity to rainfall in no-till without terraces. [ABSTRACT FROM AUTHOR]