First Advisor

Eugene Foster

Community Partner

Oregon DEQ Watershed Management Section

Date of Award

2018

Document Type

Thesis

Degree Name

Master of Environmental Management (MEM)

Department

Environmental Science and Management

Physical Description

1 online resource (vi, 63 pages)

Subjects

Water temperature -- Effect on water quality, Pacific salmon -- Habitat -- Conservation -- Oregon, Riparian areas -- Management, Water quality -- Oregon -- Middle Fork Coquille River -- Effect of shade on

DOI

10.15760/mem.42

Abstract

Warming stream temperatures degrade water quality by stressing cold-water species, promoting harmful algal blooms, lowering dissolved oxygen, and increasing the toxicity of some compounds. The influence of stream temperature on the survival of native salmon is of particular concern in the Pacific Northwest. Effective shade, the fraction of solar radiation blocked from reaching a stream, is directly related to in-stream temperature and can be manipulated by riparian management actions. Mechanistic models of effective shade are prohibitively data and cost intensive. The objective of this research was to develop an empirical model (Simple Shade) for evaluating effective shade across the state of Oregon over time on a consistent and cost effective basis. Model inputs included Normalized Difference Vegetation Index (NDVI) values derived from high-resolution aerial imagery, watershed area, topographic shading, and channel characteristics derived from digital elevation models (DEMs) and a training dataset of effective shade output from the process-based shade model Heat Source. The study area was the Middle Fork Coquille River, Oregon, and imagery data was collected in summer 2009. Principal components analysis and random forest models were used to analyze variable importance and predict effective shade. The Simple Shade model explained 45% of variation in effective shade and had a mean of squared residuals of 2.7% of effective shade units. The most important predictor variables were watershed area, mean NDVI and topographic shade angle to the South. This research demonstrated that an empirical model of effective shade has the potential to match the performance of a mechanistic model of effective shade. The correlation between shade and mean NDVI also suggested that NDVI could be a surrogate measure of effective shade. However, variability in imagery and longitudinal watershed characteristics likely obscured the relationship between NDVI and effective shade. An improved technique for normalizing image and longitudinal variability within a watershed is needed to implement Simple Shade as a tool for assessing riparian conditions across Oregon and elsewhere.

Description

The following files are included here as supplemental files:

  • APPENDIX A: Effective shade field data for Heat Source calibration
  • APPENDIX B: Simple Shade model data
  • APPENDIX C: Script for computing zonal statistics on an NDVI raster
  • APPENDIX D: Script for principal components analysis
  • APPENDIX E: Script for Simple Shade random forest modeling
  • APPENDIX F: Script for partial dependence plots

Note: Appendices C-F require the statistical computer program R in order to view.

Persistent Identifier

https://archives.pdx.edu/ds/psu/26763

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