不同降雨强度下黄土区冻土坡面产流产沙过程及水沙关系.

Seasonal freezing-thawing phenomenon occurs mainly in mid-latitudinal region, which is generally characterized by freezing in winter and melting in summer. The middle reaches of the Yellow River are in the middle latitudes, and their climatic conditions meet the requirements of freeze-thaw erosion. The soil erosion during thawing period is a special form of erosion in winter and spring, which is often caused by the combination of water erosion, gravity erosion and freeze-thaw erosion. During the soil thaw period, due to the poor thawing of slope soil and poor permeability, severe soil and water loss occurred under very small rainfall intensity. Domestic studies on soil erosion in thawing seasons are mainly concentrated in the northeastern region. However, there are few studies on the Loess Plateau region in the northwest, and few experiments have been conducted to quantitatively study freeze-thaw erosion on the Loess Plateau. Therefore, in order to study the effect of rainfall on the permafrost slope erosion on the Loess Plateau, the difference of erosion between permafrost and unfrozen soil under different hydraulic conditions is clarified. Through the indoor simulated rainfall experiment, 3 kinds of rainfall intensities (0.6, 0.9, 1.2 mm/min) and 2 kinds of slopes (frozen soil slope and control slope) were used to quantitatively study the process of runoff and sediment yield on slope as well as the relation between the runoff and the sediment under different experimental treatments. The results showed that the time producing runoff on the frozen soil slope was 18.70 and 6.44 min earlier than the control slope under the rainfall intensity of 0.9 and 1.2 mm/min, respectively. The runoff and erosion amount of the frozen soil slope were far greater than that of the control slope. The runoff at the rainfall intensity of 0.9 and 1.2 mm/min was 1.16 and 1.19 times that of the control slope respectively, and the erosion amount was 10.39 and 6.39 times respectively. As the rain went on, the slope produced different degrees of rill. The occurrence time of rill on frozen slope was shortened by 18 and 22 min, respectively, compared with the control slope, and the rill erosion on frozen soil slope accounted for 79.33%-92.02% of the total erosion amount, which was greater than that of the control slope under the same rainfall intensity. The cumulative runoff and accumulated sediment yield of the 2 slopes satisfied the linear relationship of y=kx+b, and the k value of the frozen soil slope was 8.48-9.02 times that of the control slope in the inter-rill erosion stage, while 3.68-7.50 times in the rill erosion stage. The results showed that the rill erosion was the main reason to the increase of soil erosion rate on the frozen soil slope, and the water blocking effect of the freezing layer was the most important factor leading to the advance of the emergence time of rill on the slope. This result is expected to provide some certain reference for the study of soil erosion mechanism. [ABSTRACT FROM AUTHOR]