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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Caesium-137-derived erosion rates in an agricultural setting: the effects of model assumptions and management practices
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Caesium-137-derived erosion rates in an agricultural setting: the effects of model assumptions and management practices

机译：在农业环境中源自铯137的侵蚀率：模型假设和管理实践的影响

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Soil erosion rates at the National Soil Tilth Laboratory Deep Loess Research Station in southwest Iowa (USA) were determined from Cs-137 inventories using a multi-box numerical model that incorporates time-dependent atmospheric Cs-137 deposition. Nine sites along a downslope transect where (CS)-C-137 inventories were measured in 1974 by Spomer et al. (Transactions of the American Society of Agricultural Engineers 1985, vol. 28, pp. 767-772) were revisited in 1998, allowing estimation of erosion over three time periods: 1954-1974, 1954-1998 and 1974-1998. Modelled 1954-1974 erosion rates (mean = 1(.)01 +/- 0(.)41 g cm(-2) a(-1)) were significantly higher (p < 0(.)001, t-test) than those reported by Spomer et al. (0(.)36 0(.)10 g cm(-2) a(-1)). A key reason for the significant difference is that our model used a monthly time step whereas Spomer et al. used a single 20-year time step. As the model time step was increased from 1 month to 20 years, the erosion rate decreased by a factor of three to rates in general agreement with those reported by Spomer et al. This suggests that failing to account for temporal variations in atmospheric deposition and/or cultivation practices will result in substantially miscalculated erosion rates. Erosion rates over 1974-1998 were calculated by comparing our 1998 measured Cs-137 inventory to the decay-corrected 1974 inventories reported by Spomer et al. This comparison yielded erosion rates of -0(.)10 to 0(.)48 g cm(-1) a(-1) (mean = 0(.)19 +/- 0(.)17 g cm(-2) a(-1)), indicating that soil loss was reduced by 81 52 per cent over 1974-1998 compared to the period 1954-1974. This estimate is in reasonable agreement with measurements of soil flux at the weir which indicate that soil loss has been reduced by 43 per cent since grass buffer strips were added to the field in 1991. Copyright (c) 2005 John Wiley & Sons, Ltd.
机译：美国爱荷华州西南部的美国国家土壤耕种实验室深层黄土研究站的土壤侵蚀速率是通过使用结合了随时间变化的大气Cs-137沉积的多盒数值模型从Cs-137清单中确定的。 Spomer等人在1974年测量了沿下坡样带的九个站点（CS）-C-137的清单。 （美国农业工程师学会事务1985年，第28卷，第767-772页）在1998年进行了重新研究，可以估算三个时间段的侵蚀：1954-1974年，1954-1998年和1974-1998年。模型化的1954-1974年侵蚀速率（平均值= 1（。）01 +/- 0（。）41 g cm（-2）a（-1））明显更高（p <0（。）001，t检验）比Spomer等报道的（0（。）36 0（。）10 g cm（-2）a（-1））。产生显着差异的一个关键原因是我们的模型使用了每月时间步长，而Spomer等人则使用了每月时间步长。仅使用了20年的时间步长。随着模型时间步长从1个月增加到20年，侵蚀率降低了三倍，达到了与Spomer等人报告的速率基本一致的水平。这表明，如果不考虑大气沉积和/或耕作方法的时间变化，将导致侵蚀率的计算失误。通过比较1998年测得的Cs-137库存量与Spomer等人报告的1974年衰减校正后的库存量，可以得出1974-1998年的侵蚀率。该比较得出的腐蚀速率为-0（。）10至0（。）48 g cm（-1）a（-1）（平均值= 0（。）19 +/- 0（。）17 g cm（-2） ）a（-1）），表明与1954-1974年相比，1974-1998年的土壤流失减少了81 52％。该估算值与堰上土壤通量的测量值合理吻合，该测量值表明自1991年在田间添加草皮缓冲带以来，土壤流失减少了43％。版权所有（c）2005 John Wiley＆Sons，Ltd.。

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