Impacts of Forest Disturbance on Hydrology in Large Watersheds

森林扰动对水文的影响一直是一个重要的研究课题，但大多数研究都是在小流域（<100km2）上进行的，很少对大流域（1000km2以上）进行研究。人们普遍认为，小流域的结果很难外推到大流域。大型流域研究受到进行成对流域实验的困难、数据不足、景观复杂性和缺乏公认方法的限制。然而，对大空间尺度信息的需求日益增长，以支持森林和流域管理，这突出了对大流域研究的迫切需要。在NSERC Discovery Grants（2005-2012; 2013/2014）的支持下，我们成功开发了一种分离大流域森林干扰和气候变率对水文相对贡献的研究方法，并在高影响力期刊（如Water Resources research， Journal of hydrology）上发表了该方法的应用。这项新研究（2014-2019）的目标包括：(1)在不列颠哥伦比亚省内陆的10多个大型流域应用我们完善的方法，评估森林干扰（主要是野火、山松甲虫侵扰、木材采伐或通常是它们的组合）对水文的累积影响；(2)利用VIC模型预测了未来森林干扰和气候变化情景对3个流域水文的累积效应；3)利用综合元数据分析开发新的流域特性或指数，这些特性或指数可以有效地解释大流域对流域扰动的水文响应的大变化。这些选定的流域特性或指数将有助于建立流域敏感性评价的概念框架，可在北方流域或其他地方进一步加以检验。我的长期目标是建立一个名为“大流域森林扰动、气候和水文”的研究项目，以推进流域生态系统科学。不列颠哥伦比亚省内陆有大量的大流域（35-40）和优秀的数据，这为实现我的目标提供了一个绝佳的机会。该研究将为卑诗省管理森林干扰，保护水生功能提供重要的及时信息。它将允许制定森林干扰阈值，并确定可能出现的分水岭特性或指数，以解释不同流域对森林干扰的水文反应的巨大差异。最后，本项目将培养2名HQPs和4-5名生态水文与水科学/管理专业本科生。

The impact of forest disturbance on hydrology has long been an important research topic, but the majority of this research has been conducted on small watersheds (<100km2) with rare examination of large ones (>1000km2). It is commonly accepted that the results from small watersheds are difficult to extrapolate to large watersheds. Large watershed studies are constrained by the difficulty of conducting paired-watershed experiments, and by insufficient data, landscape complexity and lack of accepted methodologies. However, growing demand for information at large spatial scales to support forest and watershed management highlights a critical need for the research of large watersheds. With the support from my NSERC Discovery Grants (2005-2012; 2013/2014), we have successfully developed a research method for separating relative contributions of forest disturbance and climate variability to hydrology in large watersheds, and the applications of the method have been published on the high-impact journals (e.g., Water Resources Research, Journal of Hydrology). The objectives of this new research (2014-2019) include: (1) applying our well-established methodology in 10 more large watersheds from the interior of British Columbia to assess the cumulative effect of forest disturbance (mainly wildfire, mountain pine beetle infestation, timber harvesting or commonly their combinations) on hydrology; (2) using the VIC model to predict the cumulative effects of future forest disturbance and climate change scenarios on hydrology in three of the selected watersheds; and 3) using an integrated meta-data analysis to develop emerging watershed properties or indices which can effectively explain large variations on hydrological responses to watershed disturbance in large watersheds. Those selected watershed properties or indices will help establish a conceptual framework on watershed sensitivity assessment, which can be further tested in boreal watersheds or elsewhere. My longer-term goal (beyond this proposal) is to establish a research program entitled “Forest Disturbance, Climate and Hydrology in Large Watersheds” to advance watershed ecosystem science. Availability of numerous large watersheds (35-40) with excellent data in the British Columbia interior provides an exceptional opportunity to achieve my goal. The proposed research will provide important and timely information for BC to manage forest disturbance to protect aquatic functions. It will allow development of forest disturbance thresholds as well as identification of possible emerging watershed properties or indices for explaining large variations on hydrological responses to forest disturbance among different watersheds. Finally, this project will train 2 HQPs and 4-5 undergraduate students who will be specialized in ecohydrology and water science/management.