From chronology to frequency pairing: a paradigm shift in the science of forests and floods

从年代学到频率配对：森林和洪水科学的范式转变

• 批准号: 194388-2011
• 负责人: Alila, Younes
• 金额: $ 1.38万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=546118
• 关键词: chronology; frequency; pairing; paradigm; shift

The science of forests and floods is embroiled in conflict and is in urgent need of reevaluation in light of changing climates, insect epidemics, logging, and deforestation. Our scientific perception of the forests and floods relation is preconceived by further reaffirmed by decades of paired watershed studies. However, the outcomes of these studies had recently been challenged because of an inappropriate experimental design factor fundamental to the paired watershed study approach. Decades of paired watershed studies focused on investigating a change in magnitude between pre- and post-harvesting floods when paired by equal meteorological or storm input. This type of chronological event pairing fails to account for the changing frequency of peak flows caused by harvesting and as a result strips a critical part of the physics from the science of forests and floods. Forests, forest harvesting or deforestation alters processes generating floods in ways that change not only the magnitude of a flood but also its frequency. Due to the highly nonlinear linkage between these two attributes of a flood event they should be evaluated simultaneously. This is best done via the framework of a peak flow frequency distribution and not the analysis of variance and covariance, as traditionally conducted in decades of forest hydrology literature. The two inextricably linked questions that should guide a research investigation of the forests and floods relation are: What is the change in magnitude (frequency) for a flood event with a frequency (magnitude) of interest? Such investigation requires a frequency-paired event analysis, where the watershed's hydrologic response of interest is the entire flood frequency distribution. We combine fieldwork with numerical modelling to re-evaluate our scientific perception of the forests and flood relation using the new experimental design of pairing flood events by equal frequency. The analysis is being conducted across a wide range of watershed sizes, hydro-climate regimes, and silvicultural systems.

森林和洪水的科学卷入了冲突中，鉴于气候变化，昆虫流行病，伐木和森林砍伐的变化，迫切需要重新评估。数十年来，成对的流域研究进一步重申，我们对森林和洪水关系的科学看法是先入为主的。但是，由于对配对流域研究方法的不适当的实验设计因素，这些研究的结果最近受到了挑战。数十年的配对流域研究重点是研究当通过相等的气象或暴风雨输入配对时，在收获前和收获后洪水之间的幅度变化。这种时间顺序的事件配对无法说明收获引起的峰值流量的变化，因此从森林和洪水科学中剥离了物理的关键部分。森林，森林收获或森林砍伐会改变洪水的过程，不仅改变了洪水的大小，而且改变了洪水的频率。由于洪水事件的这两个属性之间的高度非线性联系，应同时评估它们。最好通过峰流频率分布的框架而不是对方差和协方差的分析来完成，就像传统上在森林水文文献中所进行的那样。两个不可算的问题应指导对森林和洪水关系的研究调查的问题是：洪水事件的幅度（频率）发生了什么变化（频率）？这种调查需要进行频率分析的事件分析，其中流域对感兴趣的水文响应是整个洪水频率分布。我们将现场工作与数值建模相结合，以通过相等的频率对洪水事件的新实验设计重新评估我们对森林和洪水关系的科学感知。该分析正在各种大小，水力气候制度和造林系统进行。