Experimental Study On The Effect Of Seaweed Polysaccharide Anti-erosion Material On Slope Erosion And Sediment Yield

Soil and water loss on sloping farmland not only reduces land productivity and crop yield,but also makes soil coarser and less arable area due to the loss of fine sediment,so it is of great significance to control soil erosion on sloping farmland.For a long time,besides biological measures,tillage measures and engineering measures,soil amendments can increase the cohesion between surface soil particles,maintain good surface soil structure,prevent soil crust,increase soil infiltration rate and reduce surface runoff,thus preventing or greatly reducing soil erosion.Therefore,the research and development of this new material has become the focus of attention of experts and scholars at home and abroad.In recent years,the Changjiang River Sciences Research Institute has developed a new seaweed polysaccharide Anti-erosion Material SA-01.In order to verify its role in controlling soil erosion,the characteristics of soil erosion at different concentrations were analyzed through a series of simulated rainfall experiments.The mechanism of the effect of the new seaweed polysaccharide Anti-erosion Material SA-01 on soil erosion process was revealed through soil water repellency experiments and disintegration experiments,which provided a basis for the prevention and control of soil erosion on sloping farmland.The main results are as follows:(1)After applying SA-01,the runoff yield time on the slope increased significantly,and the runoff yield time advanced with the increase of applied concentration.Under the same slope,the runoff yield on the slope with SA-01 was higher than that on the control slope.The runoff yield on the slope decreased first and then increased with the increase of applied concentration,while the cumulative runoff on the slope decreased first and then increased with the increase of applied concentration.(2)Applying SA-01 can significantly reduce sediment yield on slope.In the initial runoff yield stage,SA-01 can significantly reduce the slope sediment yield.In the stage of surface erosion,the slope without SA-01 reaches its maximum and then falls rapidly and eventually becomes stable.Compared with the control slope,the sediment yield of SA-01 slope fluctuated slightly in the early stage of runoff yield,and the time to reach stable sediment yield was earlier than that of the control slope.SA-01 can weaken the sediment yield of slope runoff.With the increase of applied concentration,sediment yield decreases significantly.The relationship between sediment yield and applied concentration is quadratic function.(3)Soil water repellency was improved after SA-01 was applied.When the concentration was 2.5g/L,the sample retained the same hydrophilicity as the original soil.When the concentration was more than 2.5g/L,the soil began to change from hydrophilicity to repulsion.Soil infiltration rate increased significantly after applying SA-01,reached the maximum when applying 2.5g/L concentration,but decreased when increasing SA-01 concentration.(4)The results of water stability analysis of soil aggregates show that SA-01 can significantly improve the water stability of agglomerates.When the SA-01 concentration is 2.5g/L,the agglomerate water stability can be increased to more than 70%;when the concentration reaches 10g/L,the water stability index can basically reach 100%.The application of SA-01 can effectively reduce the disintegration of soil samples.When the standing time was 8 h,the disintegration rate decreased from 0.56 to 0.02 when the applied concentration was increased from 0 g/L to 10 g/L.The soil shear strength increases with the concentration of SA-01,and the soil cohesion and friction angle increase.(5)The artificial simulated rainfall experiment results show that the runoff Reynolds number increases with the applied concentration after SA-01 is applied,and the Froude number decreases with the increase of concentration.There is no significant correlation between drag coefficient F and Reynolds number Re,while there is an exponential function relationship between roughness coefficient n and Reynolds number Re.The correlation analysis of hydrodynamic parameters shows that the correlation coefficients between Reynolds number and runoff and sediment yield are 0.995 and-0.785,respectively.(6)Compared with the slope gradient,the applied concentration has a greater contribution to the runoff and sediment yield on the slope.The results of multivariate analysis of variance showed that slope gradient and applied concentration had a significant impact on slope runoff and sediment yield(P < 0.01),while the interaction between applied concentration and slope gradient had a weak impact on slope runoff and sediment yield.