不同雨强和坡度条件海涂盐土边坡侵蚀细沟发育过程

采用室内人工模拟降雨试验,在不同坡度(11.3°、21.8°、35.0°)和降雨强度(85 mm/h、110 mm/h、125 mm/h)条件下,模拟海涂盐土边坡细沟发育过程。坡面侵蚀细沟发育动态采用数码摄像进行监测,通过Image-Pro Plus(IPP)6图像分析软件对图像和数据进行整理。结果表明:(a)不同坡度和降雨强度条件下,径流产生后,很快在坡面形成细沟且细沟沟网密度变化较快;细沟数量、细沟深度、细沟平均宽度和细沟密度均随降雨时间延长而增大。(b)缓坡度条件下,土壤跌坑发育慢,细沟侵蚀率低;随着坡度增大,坡面跌坑形成后水流聚集迅速,水流侵蚀冲刷力强,细沟发育快。(c)细沟发育越深,坡面细沟数量也越多;坡面侵蚀率与细沟平均深度及水流雷诺数分别在p0.05和p0.01水平上呈显著的正线性相关关系。

Evolution process of erosion rill on saline soil slope in coastal reclamation with different rainfall intensities and slope gradients

Simulated rainfall experiments were conducted with three slope gradients(11. 3°, 21. 8°, and 35. 0°)and three rainfall intensities(85 mm/h, 110 mm/h, and 125 mm/h)to investigate the rill evolution process on saline soil slopes in coastal reclamation. The evolution process of rill erosion was recorded with a digital camera, and then the image data were analyzed with Image-Pro Plus(IPP)6 software. The results are as follows: (a)Rills formed soon after the runoff occurred and the rill density changed rapidly with different slope gradients and rainfall intensities. The rill number, rill depth, average rill width, and rill density increased with the rainfall duration. (b)At low slope gradients the drop pits developed slowly, and the rill erosion rate was low. With the increase of the slope gradient, water concentrated in the drop pits rapidly, and the erosion rate increased, leading to rapid evolution of rills. (c)The number of rills increased with the rill depth. There were significant linear positive correlations of the slope erosion rate with the average depth of rills and Re at p< 0. 05 and p< 0. 01, respectively.