ass日本风韵熟妇pics男人扒开女人屁屁桶到爽|扒开胸露出奶头亲吻视频|邻居少妇的诱惑|人人妻在线播放|日日摸夜夜摸狠狠摸婷婷|制服 丝袜 人妻|激情熟妇中文字幕|看黄色欧美特一级|日本av人妻系列|高潮对白av,丰满岳妇乱熟妇之荡,日本丰满熟妇乱又伦,日韩欧美一区二区三区在线

A rainfall simulation study was conducted to examine the effects of raindrop impact on rill erosion characteristics on the loess hillslope. The experimental treatments included three rainfall intensities (50, 75 and 100 mm/h) of representative erosive rainfalls on the Loess Plateau and three common slope gradients (10°, 15° and 20°) of rill erosion occurrence. Each experimental treatment included two surface treatments: with and without raindrop impact through placing the nylon net over the soil pan. The results showed that eliminating raindrop impact caused decreases in stable runoff rates and sediment concentrations; soil loss was induced and rill erosion was decreased by 28.1%~47.7% and 20.2%~38.6%, respectively; the increase in the contribution of rill erosion to hillslope soil erosion was induced. After eliminating raindrop impact, the effect of slope gradient on rill erosion was the same as that in treatments with raindrop impact; but the effect of rainfall intensity on rill erosion was increased. With regard to treatments with and without raindrop impact, both rill density and degree of rill dissection were increased with increase in rainfall intensity or slope gradient; but the changes of rill inclination angle were complex. Thus, rill density and degree of rill dissection were the optimal indicators to describe rill morphological characteristics. The results also indicated that raindrop impact had indirect influence on rill channel shape. That is, the degree of variation in rill width and rill depth was decreased, and rill channel shape was more inerratic after eliminating raindrop impact. With regard to treatments with raindrop impact, rill width-depth ratio was decreased with rainfall intensity or slope gradient increase. For treatments without raindrop impact, rill width-depth ratio was also decreased with increase in slope gradient, but it was slightly increased as rainfall intensity increased.