沙棘"柔性坝"对沟道水流含沙量及粒径沿程分布影响的试验研究

The effects of the seabuckthorn as a flexible dam on the sediment concentration and particle size distribution in the gully flow

为了深入研究沙棘"柔性坝"生态措施的阻水拦沙作用,在陕西眉县野外实验基地进行了沙棘"柔性坝"拦沙试验,分析与探讨了不同种植参数对砒砂岩沟道水流含沙量及粒径分布的影响。水流含沙量及粒径分布的沿程变化表明:不同参数下"柔性坝"含沙量的总体趋势为从上游到下游是逐渐减少的。坝体的上部位置含沙量逐渐减少,到了坝体中部含沙量则会增大,最后在坝体下部部位又逐渐减少,并且当坝长适中时拦沙效果才最显著,但随着坡度的不断变陡,拦沙的效果反而降低。沙棘"柔性坝"中,沿水流方向泥沙粒径呈递减趋势,并且对于粒径大于2.5μm的颗粒泥沙具有分选效果。文中研究有助于人们深入理解沙棘柔性坝滞流拦沙作用,为沙棘柔性坝这一生态工程在砒砂岩地区的推广提供理论依据。

In order to study further the retarding flow and sediment retention of the seabuckthorn- flexible dam- a type of ecological measure,a field experiment on sediment retention of the seatuckthorn- flexible dam was conducted in the experimental base located in Mei county of Shaanxi province. The impacts of various planting parameters on sediment concentration and particle size distribution in water flow in the Pisha sandstone gully were analyzed and discussed. The longitudinal variation of sediment concentration and particle size distribution showed that sediment concentration in water flow had a totally decreasing tendency from upstream to downstream under various parameters. The sediment concentration was gradually reducing in upstream of the seabuckthorn- flexible dam,then slightly increasing in the middle- stream,and again decreasing at downstream. The sediment retention effect was the most significant under the condition of appropriate dam length. However,the sediment retention effect would be getting low with the dam slope increasing. Within the seabuckthorn- flexible dam,the sediment size was decreasing along flow direction,furthermore,the seabuckthorn- flexible dam had good sorting sediment effect for the grains more than 2. 5μm in diameter. This study is helpful for people to deeply understand the retardation to flow and sediment retention of the seabuckthorn,and provides the theoretical evidence for widely spreading this type of ecological engineering- the seabuckthorn- flexible dam in the Pisha sandstone area of China.