引用本文:张德谦,倪世民,王军光,吴文枭,蔡崇法.不同侵蚀程度花岗岩红壤坡面侵蚀泥沙颗粒特征研究[J].土壤学报,2020,57(6):1387-1398. DOI:10.11766/trxb201907200268
ZHANG Deqian,NI Shimin,WANG Junguang,WU Wenxiao,CAI Chongfa.Particle-size Composition of Erosion Sediment on Granite-derived Red Soil Slope Relative to Erosion Degree[J].Acta Pedologica Sinica,2020,57(6):1387-1398. DOI:10.11766/trxb201907200268
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不同侵蚀程度花岗岩红壤坡面侵蚀泥沙颗粒特征研究
张德谦, 倪世民, 王军光, 吴文枭, 蔡崇法
华中农业大学水土保持研究中心,农村农业部长江中下游耕地保育重点实验室
摘要:
研究花岗岩红壤坡面侵蚀泥沙颗粒分选特征有助于揭示粗颗粒土壤坡面侵蚀机理。通过室内人工模拟降雨-径流试验,在15°坡度和2种试验条件下(90 mm•h-1+2.00 L•min-1、120 mm•h-1+2.66 L•min-1),研究了不同侵蚀程度(轻度侵蚀E1、中度侵蚀E2、强烈侵蚀E3)花岗岩红壤侵蚀过程及泥沙颗粒组成的变化规律。结果表明:产流率和土壤侵蚀速率随降雨强度和上方来水量的增加而增大;不同侵蚀程度土壤其侵蚀特征存在差异,产流率表现为E2>E3>E1,土壤侵蚀速率表现为E3>E2>E1;通过多元逐步回归分析得出,土体容重越高产流率越小(R2=0.800,P<0.01),更高的黏粒含量和更低的粉粒含量会使得土壤侵蚀速率减少(R2=0.715,P<0.01)。随着降雨-冲刷强度增加泥沙中砾石和黏粒含量增加,砂粒和粉粒含量减少,泥沙分形维数增大。分形维数与黏粒(R2=0.910)和砂粒(R2=-0.390)质量分数为极显著线性关系,可以作为花岗岩红壤坡面侵蚀产沙中泥沙粒级分布的评价指标。
关键词:  人工模拟降雨  花岗岩红壤  土壤侵蚀  土壤颗粒
基金项目:国家自然科学基金重点项目(41630858)和国家重点研发计划项目(2017YFC0505404)
Particle-size Composition of Erosion Sediment on Granite-derived Red Soil Slope Relative to Erosion Degree
ZHANG Deqian, NI Shimin, WANG Junguang, WU Wenxiao, CAI Chongfa
Research Center of Water and Soil Conservation, Huazhong Agricultural University, Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River) in Ministry of Agriculture and Rural Affairs
Abstract:
【Objective】Soil erosion is a main mechanism of land degradation. Much works have been done on sensitivity of coarse-textured soils to erosions different in degree, however, little is known about erosion mechanism of slopes of granite-derived red soil. An indoor simulation experiment was done to characterize runoff and sediment production on steep slopes of granite-derived red soil as affected by rainfall intensity and erosion degree and to explore erosion mechanism of slopes of coarse-textured soils.【Method】The experiment had flumes (3 m long, 1 m wide and 0.45 m high, each) packed with coarse-textured soil to simulate soil slopes different in erosion degree, two treatments in rainfall intensity (90 and 120 mm•h-1) and two in inflow rate (2 and 2.66 L•min-1). Based on field investigations and previous studies, the three slopes were designed to be slight (E1), moderate (E2) and severe (E3) in erosion degree, separately and all 16.7% in gradient, commonly seen in the hilly region in the sub-tropical climate zone of China. Before each run of the experiment, the flume was covered with a gauze to reduce the splashing impact of rain drops and then treated with a rainfall event low in intensity (30 mm•h-1) till runoff appeared at the outlet of flume. Before each run, soil moisture content in the soil slope was determined with a soil moisture meter to ensure it was no more than 30%, and rainfall intensity and inflow rate was calibrated to ensure they were up to the set requirement of the test(±5%).【Result】Results show: (1) both rainfall intensity and flow rate played important roles in runoff formation and soil erosion. Runoff yield rate and soil erosion rate increased with rainfall intensity and inflow rate, and soil erosion varied in characteristic with slope erosion degree. The slope slight in erosion degree (E1) was most affected by rainfall intensity and inflow rate. (2) The slopes varied in erosion characteristics with erosion degree erosion. The slopes exhibited an order of E2 > E1 > E3 in runoff yield rate and an order of E3 > E2 > E1 in soil erosion rate. Multi-factor stepwise regression analysis shows that the higher the bulk density, the lower the runoff yield rate (R2 = 0.8, P< 0.01) and the higher the clay content or the lower the silt content, the lower the soil erosion rate (R2=0.715, P< 0.01). (3) With rising rainfall intensity and scouring strength or inflow rate, gravel and clay contents increased, sand and silt contents decreased and fractal dimension of the sediment increased. (4) Fractal dimension was ultra-significantly and linearly related to the ratio of clay/sand in content.【Conclusion】All the findings in this study may provide a train of thought for evaluation of soil evolution under erosion and contents of the research on soil evolution.
Key words:  Simulated rainfall/runoff  Granite red soil  Soil erosion  Sediment size distribution