Riparian Buffer Removal and Associated Land Use in the Sackville River Watershed, Nova Scotia, Canada Submitted for ENVS 4901/4902 - Honours April 5, 2010 Supervisor: Shannon Sterling By Emily Rideout 0 Abstract “To what extent has riparian area been removed in the Sackville River watershed and what land uses are associated with this riparian area removal?” I investigate this question by assessing the extent of riparian area removal in the Sackville River watershed north of Halifax and characterizing each riparian impact zone with the neighbouring land use. Stream, lake and road data and air photographs are used in Geographic Information Systems (GIS) to document the degree of riparian area removal and the land uses associated with the riparian area (agriculture, industry, forestry, residential etc). I consider the riparian area to be a 20m zone extending from the water body’s edge. Over 143km of streams are assessed and all streams are broken down into reaches of discrete lengths based on riparian impact and land use category. Four qualitative indicators of riparian removal are used: Severe, Moderate, Low and Intact. The length of every reach as well as the degree of impact and associated land use are calculated using the summary statistics function in GIS. I found that one third of the total riparian area length is missing up to 50% of its vegetation and that residential, transportation and energy infrastructure were the leading drivers of this riparian buffer removal. I present a map of impacted riparian “hot spots” that will highlight the areas in which riparian area removal is the most severe as well as summaries of the land uses most associated with the greatest degree of riparian vegetation removal. Identification of the land use drivers of riparian area removal in this watershed will help the design of effective regulations for future development in riparian buffer zones. 1 Table of Contents 1. Introduction .............................................................................................................................................. 4 1.0 Overview ............................................................................................................................................. 4 1.2 Research Problem ............................................................................................................................... 6 2. Literature Review ...................................................................................................................................... 7 2.1 Riparian Ecosystem Functions & Effects of Area Removal ................................................................. 7 2.1.1 Extent of Riparian Area Removal ................................................................................................. 8 2.1.2 Land Cover Drivers ..................................................................................................................... 12 2.1.3 Policy Implications ..................................................................................................................... 14 2.2 Economic Costs of Protection of Riparian Areas............................................................................... 16 2.3 Existing Legislation in Nova Scotia .................................................................................................... 17 2.3.1 Provincial Legislation.................................................................................................................. 17 2.3.2 Municipal Legislation ................................................................................................................. 20 2.4 Identification of Literature Gaps ....................................................................................................... 23 3. Methods .................................................................................................................................................. 25 3.1 Selection of Watershed ..................................................................................................................... 25 3.2 Sources of Data ................................................................................................................................. 26 3.3 Procedures ........................................................................................................................................ 27 3.5 Sources of Error & Limitations .......................................................................................................... 30 3.6 Analysis ............................................................................................................................................. 32 3.6.1 Extent and Degree of Riparian Area Removal in Sackville Watershed ...................................... 32 3.6.2 Land Use Associated with Riparian Area Removal in Sackville Watershed ............................... 33 4. Results ..................................................................................................................................................... 34 4.1 Extent of Riparian Area Removal ...................................................................................................... 34 4.2 Land Use Drivers ............................................................................................................................... 38 5. Discussion ................................................................................................................................................ 42 5.1 Extent of Riparian Area Removal ...................................................................................................... 42 5.2 Land Use Drivers ............................................................................................................................... 42 5.3 Policy Implications ............................................................................................................................ 44 6. Conclusion ............................................................................................................................................... 47 7. References .............................................................................................................................................. 49 8. Acknowledgements ................................................................................................................................. 52 9. Appendices .............................................................................................................................................. 53 Appendix A .............................................................................................................................................. 53 Appendix B .............................................................................................................................................. 53 Figures Figure 2.1 Figure 2.1 Effects of Riparian Vegetation Clearing on Salmonid Habitat …………………….……….…9 Figure 2.2 Relationship Between Channel Morphology, Gradient & Sediment Characteristics ……….......10 Figure 2.3 Causes of Riparian Buffer Removal in the Sackville Watershed …………………………………………….12 Figure 3.1 Example of Colour Coding Methodology ………………………………………………………….…………….…….27 Figure 4.1 Severe, Moderate and Low Riparian Area Removal in the Sackville River Watershed (Left Bank Only)… ………………………………..…………………………………..…………………………………..…………………………………..…..35 Figure 4.2 Severe, Moderate and Low Riparian Area Removal in the Sackville River Watershed (Right Bank Only) ……………………………………………..…………………………………..…………………………………..……………...……36 2 Figure 4.3 Severe, Moderate and Low Riparian Area Removal in the Sackville River Watershed (Left & Right Bank Combined) …….……..……………………………………..……………………………………..…………………..….......37 Figure 4.4 Land Use Associated with Severe Riparian Buffer Removal in Sackville Watershed ………….…39 Figure 4.5 Land Use Associated with Moderate Riparian Buffer Removal in the Sackville Watershed…………………………………………………………………………………………………………………………………….………40 Figure 4.6 Land Use Associated with Severe & Moderate (Combined) Riparian Buffer Removal in the Sackville Watershed ……………………………………………………………………………………………………………..………..…...40 Figure 4.7 Land Use Associated with Low Riparian Buffer Removal in the Sackville River Watershed ….41 Figure 4.8 Land Use Associated with Intact Riparian Buffers (No Removal) in the Sackville River Watershed ……………………………………………………………………………………………………………………………………………41 Tables Table 2.1 Scope of Riparian Zone Research ……………………………………………….……………………….…….………….…8 Table 2.2 Example Ranges of Minimum Riparian Zone Widths (each side of stream) ………………..…..….…15 Table 2.3 Economic Costs of Protection of Riparian Areas ………………………………………….…………………………16 Table 3.1 Sources of Data ………………………………………………………………………………………………………………..…...27 Table 3.2 Example of GIS Attributes Table …………………………………………………………………………………………....29 Table 4.1 Extent and Degree of Riparian Deforestation in Sackville Watershed ………………………………..….34 Table 4.2 Land Uses Driving Riparian Deforestation in the Sackville River Watershed ……………………..…..38 Table 5.1 Riparian Area Removal Parameters by Land Use Category ………………………………………..……….….43 3 1. Introduction 1.0 Overview As the interface between terrestrial and aquatic habitat along streams, riparian zones play an important role in riparian ecosystem functioning. Riparian zones offer many ecosystem services including the absorption of nutrients and pollution, maintenance of in-channel