You are encouraged to attend the defence. The details of the defence and attendance information is included below:  

Date:  Monday, December 8, 2025

Time:  2:30 PM – 4:30 PM (PT)

Defence mode: Hybrid

In-Person Attendance: Senate Chambers, UNBC Prince George Campus  

Virtual Attendance: via Microsoft Teams 

Please contact the Office of Graduate Administration for information regarding remote attendance for online defences. 

To ensure the defence proceeds with no interruptions, please mute your audio and video on entry and do not inadvertently share your screen. The meeting will be locked to entry 5 minutes after it begins: please ensure you are on time.  

Thesis entitled:  HYDROLOGICAL ALTERATION IN THE NECHAKO RIVER BASIN: QUANTIFYING THE INDIVIDUAL ROLES OF CLIMATE AND FLOW REGULATION ON STREAMFLOW

Abstract: 

The Nechako River Basin (NRB), a major tributary to the Fraser River in British Columbia, is a critical watershed for migrating Pacific salmonids and First Nations cultures that depend on its flow regime. The river’s natural state has been altered by two primary drivers: extensive flow regulation since the construction of Kenney Dam, which has significantly reduced and inverted the natural hydrograph, and climate change. However, an incomplete understanding of the NRB’s natural flow regime hinders the ability to quantify and distinguish the proportional effects of these pressures on the river’s streamflow.

This research quantifies the individual impacts of flow regulation and changing climate using a two-stage comparative statistical framework. First, naturalized daily streamflow for the Nechako River at Vanderhoof and Isle Pierre (Water Years 1956-2021) were reconstructed to establish a climate-driven baseline. This was achieved with the development of a simplified routing model that used daily reservoir inflows as a proxy for unregulated headwater flows. Second, the Indicators of Hydrological Alteration (IHA) framework and Principal Component Analysis (PCA) were used to identify 12 key indicators of hydrological variability. The range of Variability Approach (RVA) and the Mann-Kendall test were then used to attribute observed changes in these indicators to either regulation or climate.

The simplified routing model was shown to be a robust method for reconstruction, achieving a Nash-Sutcliffe Efficiency (NSE) of 0.99 using unregulated data for the two-year validation period. The natural flow regime was characterized as a typical snow-dominated system with a highly predictable spring freshet. The RVA analysis revealed that flow regulation has led to a significant departure from the natural state, with annual mean flows decreasing by 46% and 45% for the Nechako River at Vanderhoof and Isle Pierre, respectively. Nearly all key indicators were moderately to highly altered, resulting in a flattened and inverted hydrograph. While trend analysis detected a climate signal of an earlier spring freshet, this was counteracted by flow regulation, which shifted the timing of annual maximums. Ultimately, flow regulation was responsible for an average of 61% and 60% of the total observed changes across key indicators of change for the Nechako River at Vanderhoof and Isle Pierre, respectively, with climate driving the remainder.

Defence Committee:  

Chair: Dr. Mauricio Dziedzic, University of Northern British Columbia  

Supervisor: Dr. Stephen Dery, University of Northern British Columbia  

Committee Member: Dr. Siraj ul Islam, University of Northern British Columbia  

Committee Member: Dr. Ryan Connon, Government of the Northwest Territories

External Examiner: Dr. Andre Zimmermann, Northwest Hydraulics Consultants