The value of a physically based model versus an empirical approach in the prediction of ephemeral gully erosion for loess-derived soils
The value of a physically based model versus an empirical approach in the prediction of ephemeral gully erosion for loess-derived soils
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DOI：
10.1016/s0169-555x(01)00046-0
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发表时间：
2001-10
期刊：
影响因子：
3.9
通讯作者：
J. Nachtergaele;J. Poesen;A. Steegen;I. Takken;L. Beuselinck;L. Vandekerckhove;Gerard Govers
中科院分区：
文献类型：
--
作者：
J. Nachtergaele;J. Poesen;A. Steegen;I. Takken;L. Beuselinck;L. Vandekerckhove;Gerard Govers
从1997年3月至1999年3月，在比利时黄土带收集了58个短暂沟的土壤流失和控制因素的数据集。所观察到的短暂的冲沟，32个开发在冬末或早春（冬季冲沟）和26短暂的冲沟开发在夏季（夏季冲沟）。评估的数据已被用来测试的物理为基础的浅沟侵蚀模型（EGEM），并比较其性能与简单的地形和形态指标的价值在预测浅沟侵蚀。分析表明，EGEM不能很好地预测浅沟断面。虽然输入参数评估的条件是理想的，一些参数，如渠道可蚀性，临界水流切应力和当地降雨深度显示出很大的不确定性。而不是揭示EGEM的预测短暂的沟蚀的能力，这种分析强调的物理模型的问题性质，因为它们往往需要输入参数，是不可用的或很难获得。相对于简单的地形和形态指标在预测浅沟侵蚀的价值，这项研究表明，冬季冲沟和夏季冲沟，分别超过80%和约75%的浅沟体积的变化可以解释时，浅沟长度是已知的。此外，当以前收集的数据在两个地中海研究领域的短暂冲沟和比利时黄土带形成的夏季冲沟的数据汇总，似乎存在一个单一的长度（L）-体积（V）的关系（V=0.048 L1.29; R2=0.91）。这些研究结果意味着，预测浅沟长度是一个有价值的替代预测浅沟体积。本文提出了一种基于地形阈值预测浅沟长度的简单方法。其次，经验的长度-体积关系也可以用来转换从航空照片提取的浅沟长度数据到浅沟体积。
A data set on soil losses and controlling factors for 58 ephemeral gullies has been collected in the Belgian loess belt from March 1997 to March 1999. Of the observed ephemeral gullies, 32 developed at the end of winter or in early spring (winter gullies) and 26 ephemeral gullies developed during summer (summer gullies). The assessed data have been used to test the physically based Ephemeral Gully Erosion Model (EGEM) and to compare its performance with the value of simple topographical and morphological indices in the prediction of ephemeral gully erosion. Analysis shows that EGEM is not capable of predicting ephemeral gully cross-sections well. Although conditions for input parameter assessment were ideal, some parameters such as channel erodibility, critical flow shear stress and local rainfall depth showed great uncertainty. Rather than revealing EGEM's inability of predicting ephemeral gully erosion, this analysis stresses the problematic nature of physically based models, since they often require input parameters that are not available or can hardly be obtained. With respect to the value of simple topographical and morphological indices in predicting ephemeral gully erosion, this study shows that for winter gullies and summer gullies, respectively, over 80% and about 75% of the variation in ephemeral gully volume can be explained when ephemeral gully length is known. Moreover, when previously collected data for ephemeral gullies in two Mediterranean study areas and the data for summer gullies formed in the Belgian loess belt are pooled, it appears that one single length (L)–volume (V) relation exists (V=0.048 L1.29; R2=0.91). These findings imply that predicting ephemeral gully length is a valuable alternative for the prediction of ephemeral gully volume. A simple procedure to predict ephemeral gully length based on topographical thresholds is presented here. Secondly, the empirical length–volume relation can also be used to convert ephemeral gully length data extracted from aerial photos into ephemeral gully volumes.