Using transfer functions to explain turbidity in Humboldt Bay, California
Graduation Date
2009
Document Type
Thesis
Program
Other
Program
Thesis (M.S.)--Humboldt State University, Environmental Systems: Mathematical Modeling, 2009
Committee Chair Name
Christopher Dugaw
Committee Chair Affiliation
HSU Faculty or Staff
Keywords
Watershed, Turbidity, Humboldt State University -- Theses -- Mathematical Modeling, Humboldt Bay, Transfer functions, Time series, California
Abstract
Humboldt Bay is one of the largest and most biologically important estuaries in California functioning as a habitat, food source, breeding ground, and nursery area for a host of marine animals. Understanding mechanisms which increase turbidity in ecologically sensitive areas, such as the Humboldt Bay watershed, is important to people making decisions on projects that affect the local watersheds and the bay. This study is the first of its kind in Humboldt Bay and is designed to model bay turbidity in terms of potentially important forcing factors such as: turbidity from the local watersheds and sediment resuspension by winds. Transfer function modeling, using the Box-Jenkins methodology, is used in this study to examine the relationships between turbidity from the local watersheds and wind speed with turbidity in Humboldt Bay for the 2005 hydrologic year. We analyzed seven storms, a full month having four major precipitation events, and the entire year. Transfer function models are identified using the sample cross correlation function. Akaike's Information Criterion is used to choose between competing models. This study found that there is some evidence, though not strong, that watershed turbidity and wind speed affects turbidity in Humboldt Bay but the mechanisms in how they affect the readings is clouded by confounding factors. The results did not indicate definitely that watershed turbidity or wind speed alone lead to a statistical significant effect in bay turbidity. When modeled together, however, there is some evidence that both inputs induced a statistically significant effect. Modeling the entire year using this technique did not yield a sufficient model since an ARMA model could not be found to reduce the residuals to a white noise process. We found the dead time, time in which a change in an input variable affects the output, between both watershed turbidity and wind speed was variable throughout the year.
Recommended Citation
Walker, Steven M., "Using transfer functions to explain turbidity in Humboldt Bay, California" (2009). Cal Poly Humboldt theses and projects. 1176.
https://digitalcommons.humboldt.edu/etd/1176
https://scholarworks.calstate.edu/concern/theses/4j03d208b