UBC Theses and Dissertations

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UBC Theses and Dissertations

Performance assessment of short-term hydrological forecasts in small, coastal watersheds with complex terrain using fully-distributed hydrological and meteorological models VanWerkhoven, Curtis


Accurate and reliable short-term streamflow forecast systems are beneficial for non-storage hydroelectric operators to minimize costs associated with foregoing electricity market opportunities because of held reserves due to forecast error and those making decisions based on flood risks. Accurate real-time forecasting on hourly and daily intervals with lead times less than three days remains a challenge in small, coastal, mountainous watersheds of the Pacific Northwest. This thesis examines a real-time streamflow forecasting system in which a physically-based, fully-distributed coupled MIKE SHE/MIKE 11 hydrologic model is driven by the distributed output of a 1.3 km gridded high-resolution numerical weather prediction (NWP) model. The model performance in simulating hydrological processes is evaluated in the model calibration and validation phases, and the forecast accuracy and reliability is evaluated in the forecast verification phase. Both performance evaluations are completed with graphical and statistical techniques based on a wide range of statistical metrics. In addition to the performance, the forecast skill is evaluated relative to alternative reference forecasts including persistence and historical climatological forecasts. The hydrologic model and forecasting system are applied to the Coquitlam River above Coquitlam Lake watershed located in the coastal mountains of southwestern British Columbia, Canada. The hydro-climate regime in the watershed is pluvio-nival, flashy, and with negligible glacier melt. High flows have a bi-modal distribution, characterized by high flows in May and June due to snowmelt and in fall (November) due to Pacific frontal systems that can bring significant precipitation. The MIKE SHE/MIKE 11 model performs well during the model calibration and validation phases, demonstrating accuracy and reliability in simulating the hydrological processes in the watershed with a one year calibration period. In addition, the forecast system provides a reliable forecast for hourly and daily mean streamflow with considerable forecast skill in comparison to reference forecasts for lead times of one to three days. MIKE SHE/MIKE 11 is demonstrated as a suitable fully-distributed, physically-based model for river forecasts based on high-resolution NWP models, and that there is the opportunity for short-term forecast skill in small, mountainous, Pacific Northwest watersheds with limited observed data.

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Attribution-NonCommercial-NoDerivs 2.5 Canada