Forests and floods: Using field evidence to reconcile analysis methods
Forests and floods: Using field evidence to reconcile analysis methods
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DOI：
10.1002/hyp.13802
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发表时间：
2020-06-05
影响因子：
3.2
通讯作者：
Jones, Julia
中科院分区：
文献类型：
--
作者：
Bathurst, James C.;Fahey, Barry;Jones, Julia
相对于较矮的植被，森林缓解洪峰流量的程度仍然存在争议，研究相对较少，只有少数重要的实地研究。考虑到纯粹的影响，植被覆盖的变化，峰值流量大小比较成对的集水区表明，森林不减轻大洪水，而洪水频率比较表明，森林减轻频率在所有大小的洪水。本研究使用基于实地的证据，从0.34-3.1公里尺度的四个对比实地方案中调查了明显的不一致性（2）。重复的模式被识别，提供了强有力的证据与物理解释的真实的影响。幅度和频率的比较都与森林对峰值流量的影响有关，但涉及不同的问题。两者都可以显示在有记录的最高流量下，森林和草原/伐木状态之间的响应收敛，但相关的重现期可能变化很大，并且受到估计不确定性的影响。对于低到中度事件，森林集水区有一个较低的峰值幅度为一个给定的频率比草地/记录集水区。根据先前的土壤饱和度，一个给定的风暴可能会产生相同大小的峰值流量的集水区状态，但这些峰值将有不同的重现期。植被覆盖变化的影响可能会被额外的林业干预措施所改变，例如道路网络和排水沟，通过有效地增加排水密度，可能会增加所有事件量级的峰值流量。对于所有地点，森林覆盖大大减少了年径流量。
The extent to which forests, relative to shorter vegetation, mitigate flood peak discharges remains controversial and relatively poorly researched, with only a few significant field studies. Considering the effect purely of change of vegetation cover, peak flow magnitude comparisons for paired catchments have suggested that forests do not mitigate large floods, whereas flood frequency comparisons have shown that forests mitigate frequencies over all magnitudes of flood. This study investigates the apparent inconsistency using field-based evidence from four contrasting field programmes at scales of 0.34-3.1 km(2). Repeated patterns are identified that provide strong evidence of real effects with physical explanations. Magnitude and frequency comparisons are both relevant to the impact of forests on peak discharges but address different questions. Both can show a convergence of response between forested and grassland/logged states at the highest recorded flows but the associated return periods may be quite variable and are subject to estimation uncertainty. For low to moderate events, the forested catchments have a lower peak magnitude for a given frequency than the grassland/logged catchments. Depending on antecedent soil saturation, a given storm may nevertheless generate peak discharges of the same magnitude for both catchment states but these peaks will have different return periods. The effect purely of change in vegetation cover may be modified by additional forestry interventions, such as road networks and drainage ditches which, by effectively increasing the drainage density, may increase peak flows for all event magnitudes. For all the sites, forest cover substantially reduces annual runoff.