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首页> 外文期刊>The holocene >Reconstructing rainfall and land-use conditions leading to the development of old gullies
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Reconstructing rainfall and land-use conditions leading to the development of old gullies

机译：重建降雨和土地利用条件，导致老沟渠的发展

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Knowledge of past erosion events and their controlling factors is an important key to understanding the impacts of environmental change (climate-land use) on the landscape. In this study knowledge about erosion processes on the development of present-day ephemeral gullies is used for reconstructing conditions leading to the formation of old, permanent gullies. Empirical relations between flow hydraulics and channel geometry have been recently established for gullies. Hence, using measured bottom width W_(bottom) of old gullies as input, peak flow discharges (Q_p) of these gullies can be estimated. In two forested areas in central Belgium, 52 old gullies were mapped. The old gullies had an average W_(bottom) ranging between 1.1 and 1.5 m. Corresponding calculated Q_p values ranged between 0.04 and 0.07 m~3/s. Rainfall intensities (I) were also deduced from Q_p using the rational formula. By simulating various land use scenarios and thus various runoff coefficient (C) values, I and concentration time (T_c) could be calculated for each land-use class. Using I, T_c and intensity-duration-frequency tables for the study area, the recurrence interval (RI) of the rain events, needed to erode the observed gully channels was assessed. Although analysis of historical documents indicates that both areas have probably been under forest since the Middle Ages, it is unlikely that the old gullies originated under forest vegetation or even degraded forest vegetation, since RI > 200 years were obtained for these land-use scenarios. Cropland is the only land use that provides acceptable values of RI (11 - 128 years).
机译：了解过去的侵蚀事件及其控制因素是了解环境变化（气候土地利用）对景观的影响的重要关键。在这项研究中，关于腐蚀过程的知识在当今短暂的沟壑发展中被用于重建导致形成旧的永久性沟壑的条件。最近已经为水沟确定了水力流与通道几何形状之间的经验关系。因此，使用测量的旧沟渠的底部宽度W_（底部）作为输入，可以估计这些沟渠的峰值流量（Q_p）。在比利时中部的两个森林地区，绘制了52个老沟壑的地图。老沟渠的平均W_（底部）在1.1到1.5 m之间。相应的计算Q_p值在0.04至0.07m〜3 / s之间。还使用有理公式从Q_p推导出降雨强度（I）。通过模拟各种土地利用情景，从而模拟各种径流系数（C）值，可以为每种土地利用类别计算I和集中时间（T_c）。使用研究区域的I，T_c和强度持续时间频率表，对侵蚀观测到的沟渠通道所需的降雨事件的复发间隔（RI）进行了评估。尽管对历史文献的分析表明，自中世纪以来，这两个地区都可能处于森林之下，但由于这些土地利用情景获得的RI> 200年，因此旧的沟壑不太可能起源于森林植被甚至退化的森林植被。农田是唯一可以提供可接受的RI值（11-128年）的土地用途。

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