Study on Spatial and Temporal Process of Soil Erosion on Brown Earth Sloping Land during Natural Rainfall
|School||Shenyang Agricultural University|
|Course||Soil and Water Conservation and Desertification Combating|
|Keywords||Natural rainfall REE tracer method Soil Erosion Raindrops characteristics Erosion Rate of soil erosion|
Hillslope soil erosion evolution and mechanism is the focus of the study of soil erosion has always been a direct impact on soil erosion prediction model. Under field conditions, the study the natural continuous rainfall conditions hillslope erosion evolution of a more realistic slope erosion significance. Under natural rainfall conditions, 5 °, 10 ° and 15 ° three different slope runoff plots a combination of rare earth elements layered segment laid observation runoff and sediment yield process, continuous natural rainfall conditions evolution of hillslope erosion sediment sources and erosion; the study hillslope soil erosion rates and sediment concentration change over time; based on trials rainstorm erosion data heavy rain hillslope the erosion morphology and rill erosion The evolution of the spatial and temporal characteristics; using filter paper stain on natural rainfall raindrops collection, analysis of the characteristics of the days raindrop. Made the following conclusions: (1) the natural rainfall raindrops features low-intensity rainfall mainly from small raindrops, high intensity rainfall mainly by large raindrops, erosive rainfall runoff and sediment yield process, the number of raindrops in diameter (D 50 ) is usually greater than 3mm; distribution of raindrops to comply with the Best the model F = 1-exp [- (d/6.18i 0.29 sup>) n sup>, n = 3.055i -0.092 sup>; exponential function relationship between number diameter with rain in the raindrops (D 50 = 6.11i 0.31 sup> ); between rainfall kinetic energy and rainfall intensity also showed a power function relationship (e = 50.73i 0.23 sup>). (2) the variation of different type rain Runoffs and Sediment the short lasted showers runoff process, the slope in rainfall runoff runoff rate after a short duration of stagnant, then reaches a maximum; subsequent runoff The rate is gradually reduced until the slope to stop the runoff. Slope sediment production is also influenced by the rainfall intensity, its variation is similar to the law of overland flow. , Drizzle rain type rate of runoff and sediment yield rate is relatively small; single rainstorm process of overland flow and rainfall intensity is closely related to the production flow rate showed the same trend as the changes in rainfall intensity rainfall intensity and runoff rate, sediment yield rate of the three peak values ??the same time. (3) the slope of the rill development affect the slope of the rill development with increasing slope, slope evolution sooner, faster. August 8, the end of rainfall, 5 ° slope lower part of the erosion to a depth of 5-15cm the rill is in the initial stages of the development; 10 ° and 15 ° slope lower part of the erosion depth of 10-15cm, rill in the developmental and stable phases. (4) the rainstorm process hillslope erosion and sediment yield variation in Runoff and sediment processes in hillslope erosion rate is relatively large, with the advent of storm peak, the erosion rate of the tracer region have also appeared high peak ; the the erosion contribution rate of each tracer District during rainstorm relatively stable; 15 ° slope rill fully developed paragraph A, B segment, segment C and D segment relative erosion were: 82.5% 6.9%, 3.3% and 7.3%, the paragraphs erosion ratio: 1:0.08:0.04:0.09. (5) nonlinear the slope segment soil erosion rate and sediment concentration variation of rainfall runoff process, the silt content of each slope segment sequentially increased from the top of the hill to the foot of the slope, the the slope segment soil erosion rate peak the same rainfall instantaneous rainfall intensity peak corresponding to the basic; rate of soil erosion and sediment concentration of each slope segment between rainfall events was significant the power function relationship (D , r = aS w b sup>); rate of soil erosion and sediment concentration in the whole year of continuous rainfall process was exponential relationship between (D r = aS < sub> w b sup>).