Watershed disturbance analysis
Ian Lange
Economics
Environmental Management
My projects use a relatively new statistical technique called a wavelet analysis to look at the variability of water temperature in streams of the Willamette River Basin that have multi-purposes control dams on them. My work is co-authored with Ashley Steel of the Northwest Fisheries Science Center. Using time series data from the United States Geological Survey, we paired up sites above and below a dam and sites that span before and after the construction of a dam. With this data, we calculated the wavelet variance for each along with the confidence interval around each estimate. Regression results indicate that the mean wavelet variance is smaller after water has passed through a dam. These results suggest that the construction of flood control dams in the Willamette River Basin have lowered the variability in stream temperature. We argue that a wavelet variance is a superior metric for determining changes to water temperature regimes over time.
Future research will focus on the variability of stream flow in addition
to water temperature in streams in the Willamette River Basin in response
to other watershed modifications.