Calibration of simulated rainfall characteristics for the study of soil erosion on agricultural land.
Calibration of simulated rainfall characteristics for the study of soil erosion on agricultural land.
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DOI：
10.1016/j.still.2009.07.005
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发表时间：
2009-12
影响因子：
6.5
通讯作者：
J. Ries;M. Seeger;T. Iserloh;S. Wistorf;W. Fister
中科院分区：
文献类型：
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作者：
J. Ries;M. Seeger;T. Iserloh;S. Wistorf;W. Fister
降雨模拟是研究农田土壤侵蚀的常用方法。这种试验研究方法的主要问题是不同模拟器模拟的降雨量存在差异，从而影响了模拟器之间的可比性。因此，本研究的目的是描述在过去几十年中广泛使用的降雨模拟器产生的降雨。使用四种不同的校准方法来评估液滴尺寸分布：（1）指示纸，（2）Plaster Micro Plot，（3）Joss-Waldvogel Disdrometer和（4）激光测距仪（Thies）。此外，后者还用于测量液滴下落速度和液滴直径。用100个雨量计测定了样地上的降雨空间分布格局。降雨的空间分布模式明显地表现出不均匀性，这是由所使用的喷嘴配置造成的。根据所使用的测量技术，可以观察到液滴尺寸分布的相当大的差异。激光粒度仪和石膏微图涵盖了整个生产的液滴尺寸范围从<0.5mm to >3.0毫米，而指示纸以及乔斯-瓦尔德沃格粒度仪主要显示小于2.0毫米的液滴。因此，降雨的特征在很大程度上取决于所使用的方法，如果使用不同的方法，可能会导致相互矛盾的结果。激光测距仪反射的体积滴尺寸分布与强度为40 mmh −1的雨产生的体积滴尺寸分布非常相似。然而，与自然降雨相比，最大速度超过10 ms − 1的小雨滴速度太快，而速度主要低于5 ms − 1的大雨滴速度太慢。作为一个整体的结果，模拟器的特点是适合径流和渗透测量，但由于空间降雨分布的再现性低的限制。由于所产生的液滴谱和下落速度，侵蚀量可能被系统地低估。为此，方法的发展必须集中在均匀的空间降雨分布，并在更高的下降速度增加大滴的数量。
Rainfall simulation is a widely used method for soil erosion studies on agricultural land. Major problem of this experimental research method is the comparability between different simulators due to differences in simulated rainfall. Therefore the purpose of this study is to characterize the rainfall produced by a rainfall simulator which was widely used during the last decades. Four different calibration methods were used to assess the drop size distribution: (1) Indication Paper, (2) Plaster Micro Plot, (3) Joss–Waldvogel Disdrometer and (4) Laser Distrometer (Thies). Additionally, the latter one was used to measure drop fall velocity in combination with drop diameter. The spatial rainfall distribution pattern on the plot was measured with 100 rainfall gauges. The spatial rainfall distribution pattern clearly shows a heterogeneity, which is caused by the used nozzle configuration. Considerable differences in drop-size distribution can be observed depending on the used measurement technique. Laser Disdrometer and Plaster Micro Plot cover the whole produced drop size spectrum ranging from <0.5mm to >3.0mm, whereas Indication Paper as well as the Joss–Waldvogel Disdrometer primarily show drops smaller than 2.0mm. Characterisation of rainfall is therefore strongly dependent on the used method and if different methods are used, may lead to contradictory results. The volume drop size distribution reflected by the Laser Distrometer is very similar to that one produced by rain with an intensity of 40mmh−1. Nevertheless, with maximum velocities above 10ms−1small drops are by far too fast and large drops with velocities dominantly below 5ms−1are too slow compared to natural rainfall. As an overall result, the simulator can be characterised as suitable for runoff and infiltration measurements, but with constraints due to the low reproducibility of the spatial rain distribution. As a consequence of the produced drop spectrum and fall velocity the erosion quantities may be underestimated systematically. For this, methodological development has to be focussed on homogeneous spatial rainfall distributions and on increasing the amount of large drops with higher fall velocities.