红壤区坡面径流小区全剖面采样方法探讨

Discussion on method of the depth profile sediment sampling of slope runoff plot in red soil region

坡面径流小区径流桶含沙量测量是坡面径流小区水土流失监测的关键。本文通过在1.05kg/m^(3)、5.25kg/m^(3)、10.49kg/m^(3)、52.46kg/m^(3)、104.92kg/m^(3)、524.58kg/m^(3)6个含沙量水平,30cm、60cm、90cm 3个不同水深径流桶下进行全剖面取样器取样实验测量精度分析,结果表明:全剖面取样器采样法在红壤坡面径流小区径流桶的含沙量观测的相对测量误差范围在约-35.19%~0.65%,低含沙量下其测量误差有正负,相对误差随含沙量增加先减小后增大,测量精度的稳定性随含沙量增加而减小;全剖面取样器采样法在低、中含沙量水平下水深从30cm到90cm,随着水深增加相对误差显著增加,高含沙量下水深对测量精度无显著影响;全剖面取样器采样法适合红壤区径流小区径流桶中、高含沙量条件下取样观测。

The accurate measurement of sediment concentration in collecting tanks of slope runoff plots is a key to monitor slope soil erosion.In this paper,the measurement error of the depth profile sediment sampler is studied by laboratory experiment.The experiments involved 3 different water depth runoffs of 30cm,60cm,and 90cm,6 sediment concentration levels of 1.05,5.25,10.49,52.46,104.92 and 524.58 kg/m^(3).The results showed that sediment content measured was less than true value with the error ranging from-35.19%to 0.65%.The measurement error had different influence under the condition of low sediment concentration,and the relative error first decreases and then increases with the increase of sand content.The stability of the measured data decreases with the increase of the sand content.The measurement error of the depth profile sediment sampling increases significantly as the water depth increases in the low and medium sediment concentration levels from 30cm to 90cm.However,the water depth under high sediment concentration has no significant impact on the measurement accuracy.The depth profile sediment sampler is suitable for sampling under the condition of medium and high sediment concentration in runoff bucket of runoff plot in red soil region.