Using a Nested Watershed Approach to Assess Cumulative Effects of Forest Disturbance on Hydrology in a Sub-Boreal Forested Watershed

点击翻译按钮获取中文摘要

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 (<100 km2) with rare examination of large ones (>1000 km2). With the support from my NSERC Discovery Grants (2005-2012; 2013/2015), we have successfully developed a method for separating relative contributions of forest disturbance and climate variability to hydrology, and the applications of the method have been published on the high-impact journals (e.g., Water Resources Research, Journal of Hydrology). Our progress has led an important research question, which will be addressed in this proposal. As our previous studies normally treated large watersheds as “black boxes”, they would not lead to understanding of underlying mechanisms and processes which govern the cumulative hydrological responses to forest disturbance in large watersheds. Thus, a critical research need is to assess how forest disturbance cumulatively influences hydrology over different spatial and temporal scales. To address this question, a nested watershed approach is required. In this proposed study, I will use the Similkameen River watershed (containing 9 nested and gauged sub-watersheds) located in the Southern Interior of British Columbia as an example to study the cumulative effects of forest disturbance on hydrology. The objectives (2015-2020) include: (1) assessing the cumulative effects of forest disturbance and climatic variability on hydrology for each sub-watershed; (2) applying the VIC (Variable Infiltration Capacity) model to simulate the cumulative effects of future forest disturbance, climatic variability and watershed property on hydrology for each sub-watershed; and 3) exploring scaling properties which can be used to understand possible governing mechanisms and infer hydrological sensitivity to watershed disturbance at various spatial scales. My longer-term goal is to apply geochemistry and landscape approaches to examine more mechanisms (e.g. surface water and groundwater interactions) in this large watershed to further advance watershed science. The proposed research will provide important and timely information for British Columbia to manage forest disturbance to protect aquatic functions. It will allow development of forest disturbance thresholds as well as identification of possible emerging scaling and watershed properties for inferring the cumulative hydrological responses to forest disturbance among different watersheds. Finally, this project will train 2 HQPs and 4-5 undergraduate students.