黄土峁坡农地侵蚀与坡长的关系

Relation Between Erosion of Slope Farmland of Loess Mound and Slope Length

采用^(137)Cs法测定土壤侵蚀量和细沟量测的综合研究表明,黄土峁坡的长坡农地,在细沟最大深度未抵达犁底层的坡长范围内,侵蚀速率与坡长呈正相关,大于此坡长后不呈正相关.犁耕层和犁底层组成的双层土壤结构,控制了峁坡农地的细沟发育,决定了侵蚀速率与坡长的关系.径流小区的坡面径流汇聚和细沟发育情况往往与实际峁坡农地差异较大,依据径流小区观测资料统计得出的峁坡农地的侵蚀速率与坡长呈正相关的结论,不适用于长坡农地.

According to the measurement result of erosion amount and rills variation in the loess mound by ' Cs measurement, the authors considers that within the range of slope length on which the biggest depth of rills does not reach the plowpan, erosion rate of farmland with long slope takes positive relationship with slope length; when more than the slope length, erosion rate does not take positive relationship with slope length. The double-layer soil structure composed by plowpan and ploughing layer controls the development of rills on slope farmland of loess mound and determines the relation between erosion rate and slope length. Confluence of slope runoff and development of rills on runoff plot have great difference with those on actual farmland of mound slope, therefore the conclusion drawn with the survey data from runoff plot that erosion rate of farmland on mound slope takes positive relation with slope length does not fit to farmland with long slope.