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Northwest A&F University (2013)

Simulation Experiment of Aeolian-fluvial Interaction of Loess Soil on the Loess Plateau

张庆印;

Titre : Simulation Experiment of Aeolian-fluvial Interaction of Loess Soil on the Loess Plateau

Auteur : 张庆印;

Grade : Master’s Theses 2013

Université : Northwest A&F University

Résumé
The water-wind erosion crisscross region on the Loess Plateau has its own uniqueenvironmental background, making the mechanism and processes of Aeolian-fluvialinteraction different with the processes of the unique wind erosion or water erosion. Theecological environment is very fragile and can be engaged in agricultural production, butunreasonable operation can lead to the destruction of the ecological balance and the serioussoil and water erosion, even to the irreversible desertification. The form of soil and watererosion in the area is different from the other regions due to the unique topographical featuresin the water-wind erosion crisscross region on the Loess Plateau. A large number of studieshave shown that the area is water erosion and wind erosion pastoral zone, thus the strongAeolian-fluvial interaction is one of causes of the fragile environmental formation. Therefore,it is necessary and guiding to study the mechanism and processes of Aeolian-fluvialinteraction for preventing and controlling the water and wind erosion and it is practicalsignificant for promoting regional sustainable development and the ecological balance in thefuture. Therefore, the effect of water erosion on wind erosion was studied by artificialprecipitation and wind tunnel in order to reveal the objective law of the water and winderosion and mechanism of Aeolian-fluvial interaction in the water-wind erosion crisscrossregion on the Loess Plateau, the main conclusions are as follows :(1)The sediment yields of wind erosion was influenced by the rill width, depth anddensity. The sediment yields of wind erosion increased with the rill width and density duringthe certain range, and the sediment yields of wind erosion presented a positive relation withthe rill width and density ; It was not obvious in the relationship of the sediment yields of winderosion and rill depth. But in the4 8cm range, the sediment yields of wind erosion increasedwith the depth, while decreased when the depth is over8cm. The sediment yields of winderosion reach the maximum when the rill depth was8cm. But the sediment yields of winderosion piled up at the rill head and bottom no matter how the rill width, depth and densitychanged, and these loose deposition were easily eroded by the slope runoff. Thus the materialconditions provided each other was the main reason for the strong erosion in the water-winderosion crisscross region.(2)The maximum of wind erosion did not appear at the bottom of the wind tunnel, butat a certain height from the surface of sand section due to the influence of the slope of the test soil bin and the head of the rill. These revealed that the trajectory of the particles from winderosion was not the conventional saltation. Wind kept a turbulent state in the rill and thesand-driving wind weaken the soil anti-wind erosion owing to the abrasive and striking action.Thus, soil occured wind erosion easily and formed the collapsed rill wall and the extension ofthe rill head.(3)In the continuous simulated rainfall experiment, the runoff-yielding time, runoff,sediment yield and sand content of runoff changed with the rainfall intensity. This change wasassociated with the difference of wind erosion and rainfall intensity. The runoff-yielding timeprimarily depended on wind speed and rainfall intensity, and the rainfall had a significantimpact on the runoff-yielding time. Under the different rainfall intensity, runoff increased withtime totally while the sediment yields increased with time at the earlier and then reducedappreciably and increased sharply finally. During the initial0 25min of the rainfall, therunoff and sediment yields after the violent wind erosion were less than the runoff andsediment yields after the slack wind erosion separately, however they were just the opposite atlater stage.(4)The rill reduced the resistance of soil to wind erosion, and the wind erosion rate wasincreased greatly. But the wind erosion before the rainfall damaged the soil structure, and thewind erosion supplied abundant eroded particles for the water erosion. The rill developedafter the rainfall also provided the wind erosion with favorable condition. So both do promoteeach other and occur alternately

Mots clés : Loess Plateau; Loess soil; Aeolian-fluvial interaction; Rill; Rainfall intensity; Degree of wind erosion; runoff yield; Sediment yields; Soil anti-erosion;

Présentation (CNKI)

Page publiée le 12 juin 2018