喀斯特裸坡产流产沙过程试验研究

运用可调坡度、地下孔(裂)隙度试验钢槽装填土石模拟喀斯特裸坡,采用人工模拟降雨的方法探索了喀斯特裸坡产流产沙过程。结果表明:降雨强度、坡度和地下孔(裂)隙度对喀斯特裸坡产流产沙均有明显的影响。(1)在30、50、80mm/h降雨强度下地表产流产沙存在临界降雨强度,临界降雨强度在50—80mm/h之间,地下孔(裂)隙产流量和产沙量均随降雨强度增大呈现先增大后减小的变化趋势,产流量随降雨强度变化顺序为503080mm/h,产沙量随降雨强度大小变化顺序为508030mm/h。(2)随着坡度增大,地下输沙模数减小,其大小随坡度变化的顺序为10°15°20°25°;同一降雨历程内,坡度越小,单位时间内的地下输沙模数减小量越大,其大小随坡度变化的顺序为10°15°20°25°。(3)地下孔(裂)隙度对地下产流产沙影响显著,地下孔(裂)隙度的增大使地下流失量增大。地下产流比重、产沙比重均随地下孔(裂)隙度的增大而增大,大小顺序均为1%3%5%。研究有助于深入了解喀斯特坡地土壤侵蚀机理,为喀斯特石漠化治理和生态修复提供理论依据。

Runoff and sediment production processes on a Karst bare slope

Artificial rainfall experiments were carried out on a simulated Karst bare slope in a steel tank, where the slope and degree of underground holes (cracks) could be adjusted, to study the production processes of runoff and sediment in these environments. During experiments, the tank was filled with soils and rocks. Results indicated that rainfall intensity, slope and degree of underground holes (cracks) had obvious influences on runoff and sediment production processes. (1) Sediment was produced from the soil surface when the actual rainfall intensity was greater than the critical rainfall intensity of 50-80 mm/h. Runoff and sediment yield changed with varied rainfall intensities, and the order of the runoff yield for three rainfall intensities was 50 > 30 > 80 mm/h, and the order of the sediment yield for three rainfall intensities was 50 > 30 > 80 mm/h, respectively. (2) The underground sediment transport modulus decreased with increased slope, and the order of the sediment transport modulus for four slopes was 10° < 15° < 20° < 25°. In the same rainfall event, we noted that the smaller the slope, the greater the sediment transport modulus reduction per unit time, and the order of the sediment transport modulus for the four slopes was 10° > 15° > 20° > 25°. (3) The degree of underground holes (cracks) had a significant effect on underground runoff and sediment yields. An increase in the degree of underground holes (cracks) led to increased underground soil erosion. Underground runoff and sediment yields increased with an increase in the degree of underground holes (cracks), and the order of underground runoff and sediment yields for three underground hole degrees was 1% < 3% < 5%. This study provides a deeper understanding of the mechanisms of soil erosion in Karst slope habitats and provides a theoretical basis for the management of rocky desertification control and ecological restoration.