Module 2 - Ecological Restoration Flashcards
Ecological Restoration definition
Ecological restoration aims to enable the recovery of the resilience and adaptive capacity of ecosystems that have been degraded, damaged, or destroyed
Key Ecological Values
Conserving viable populations of native species
Conserving ecosystem diversity
Maintaining evolutionary and ecological processes
Managing over long time frames to maintain evolutionary potential
Accommodating human use and occupancy within these constraints
Evaluating restoration success
- Species diversity and composition reflects reference ecosystem
- Presence of indigenous species
- All functional groups represented
- Physical environment can sustain reproducing populations
- Function at time,
t, matches its development stage - Integrated with neighbouring ecosystems
- Potential threats/risks eliminated
- Resiliency to normal stress events
Key stream features
Rivers are ever-changing, with or without human intervention
Dynamic throughput of sediment, nutrients etc.
Exist in a wide variety of geographical and topographical situations
Variety of form
River ecosystem services: Consumptive provisioning Non-consumptive provisioning Regulation Supporting services Cultural/social
What makes a healthy functioning stream?
- Range of flows and functioning floodplain
- Resilience to droughts and floods
- Ability to transport sediment
- Bed stability and diversity
- Bank stability
- Diversity of habitat
- Riparian buffer
Drivers for stream restoration - Impairments and consequences
Impairments • Straightening • Dredging • Floodplain infill • Watershed manipulation • Stormwater • Pollution point source discharges • Utilities, culverts, infrastructure • Buffer removal
Consequences • Loss of water quality • Habitat loss • Land loss • Safety issues • Infrastructure damage • Flooding • Aesthetics
Stream Restoration Design concepts
Hydrology Sedimentology Morphology: sinuousity Slope modification Habitat: Both riparian and instream habitat Connectivity: Culverts
Key concepts for Designing stream crossings
- Avoidance of overly steep or perched culverts
- Shortest crossing distance possible
- Match natural bankfull width
- Culverts to maintain base flow at its normal width, depth and velocity
- Use of cross vanes upstream to control flow direction, sediment transport
Case study: Ōtākaro/Avon River Precinct redevelopment key features
In-stream:
- Split river into riffle, run and pool zones
- Narrowing river sections:
- Speeds up water
- Sluices out silt
- Exposes rougher substrate
- Addition of bankside rocks that are rough and irregular
- Legacy sediment removal: Sandwand
Surrounding area:
- Increased bankside planting:
- Reduce number of mallards
- Provides spawning and protective habitat for inanga
- New planting to focus on natives that provide habitat and food for native birds
- Maintain exotic heritage trees such as poplars and cherries
- Provide stormwater treatment (e.g. via raingardens) before discharge to the river
Examples of engineering techniques Ōtākaro/Avon River Precinct redevelopment
- Computational modelling to predict water levels with the proposed new cross-sectional configuration for different flows
- Flood inundation mapping
- Water quality monitoring and analysis
- Design and construction of stormwater treatment systems
- Project management of a interdisciplinary team
- Construction monitoring
Natural and Physical Built and Non - physical built Barriers
Natural: Waterfall Swamp Overhangs Others: Low water levels / dry stream bed, Uninhabitable zone
Physical Built Barriers: Falls/weirs, Dams Chutes(High velocity zones) Screens Overhangs
Non-physical Built Barriers: Air bubble curtains Acoustic Electric Light Chemicals
Barrier design to prevent trout
V-notch or similar crest profile Minimum fall height > 1.5 m Small drops (< 2.5 m) should be combined with other barrier mechanisms ≥ 500 mm overhangs to inhibit jumping
Barrier Design considerations include
Location and reach profile Response to varying flows Upstream effects Downstream effects Sediment Erosion protection Dimensions and crest profile Foundations and connections Habitat health
Define the species of concern: Trout Salmonids Carp Koaro
Strong swimmers Strong jumpers Climbers Sound sensitive
X X
X X
X
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Diadromous Fish
Migratory Fish
