Abstract:Freezing-thawing is one of the main external forces of soil and water loss on slopes during spring thawing period. In order to study the erosion and sediment yield process under the condition of runoff scouring on frozen-thawed slopes, two slope gradients (10, 15 degrees), three flow rates (3, 6, 9 L/min) and two initial thawing depths (6, 12 cm) were used to carry out field scouring tests with close-range photography. The sediment yield under different thawing depths, slopes and discharge conditions was analyzed by measuring technique. The close-range photogrammetric measurements and measured values were fitted by linear regression equation. The results showed that under the same conditions of initial thaw depth and slope, the soil erosion and sediment yield on the freeze-thaw slope increased with the increase of flow and slope; with the passage of time, the sediment yield would be smaller and smaller. At the same flow and gradient, the sediment yield increased with the initial thaw depth. When the flow rate and thaw depth were the same, the sediment yield increased with the increase of slope. When the discharge, thaw depth and slope were the largest, the erosion and sediment yield on the slope reached the maximum. Compared with the close range photogrammetry, the average error of the measured sediment yield was 90.67%. The close range photogrammetry technology can be applied to soil erosion monitoring under freeze-thaw conditions.