Restoration

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Restoration

• Currently, a huge topic, not only with respect to
  contaminated rivers, but degraded rivers in
  general
• Current federal initiatives call for the
  restoration of 25,000 miles of stream corridor
  and the re-establishment of 2,000,000 miles worth
  of conservation buffer zones Also 100,000 acres
  of wetlands (USEPA, 2000).
• This will cost millions of

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Original Definition(after Berger, 1990)

• Restoration is the structural and functional
  return of a degraded riverine ecosystem to its
  pre-disturbance condition.
• Goal is to emulate a natural functioning,
  self-regulating system that is integrated with
  the ecological landscape in which it occurs.
• The pre-disturbance condition is generally
  considered to be the state of the river prior to
  European settlement (in the U.S.) Commonly
  considered the Bronze age in Europe.
• Several problems with the assumption.

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Problems with Using Pre-Settlement Conditions as
Restoration Goal

• The Pre-Colombian ecosystems are assumed to be
  those that are healthy this may or may not be
  true
• This idea objective can rarely be achieved
  because (after Hobbs and Norton, 1996)
• We do not generally know what the structure,
  function, composition or dynamics of these
  ecosystems was like
• Even if we did, the pre-disturbance condition may
  not fit the modern stable state(s) because the
  system has evolved.

4
Alternate Definition (USEPA, 2000)

• Restoration is the return of a degraded ecosystem
  to a close approximation of its remaining natural
  potential.
• Based on the idea that you can only restore the
  ecosystem to what the climate, geology,
  hydrology, etc. will support.
• So, determine what was once there, what the
  environment will now support, and then develop
  realistic objectives regarding how the degraded
  system can be moved to a direction of what it
  will support. (very different from original
  definition).

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Use of Alternative Definitions

• Rehabilitation (Waal et al., 1998) A process
  which can be defined as the partial functional
  and/or structural return to a former or
  pre-degraded condition or putting back to good
  working order.
• Some significant advantages for the use of this
  definition, but it is not applied much in the U.S.

6
Are Restorations Successful?

• Numerous successes have been described in the
  literature (National Resources Council, 1992
  FISRWG, 1998), but it is recognized that riverine
  ecosystems are extremely complex and their
  response to physical and biological manipulations
  are not easy to predict. (i.e., there have been
  a lot of failures!)
• In fact, Kondolf (1995) argues that restoration
  projects should be viewed as experiments from
  which we can learn from our successes and
  failures

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Lack of Scientific Approach

• Current restoration projects are not being done
  in a very organized, coherent method.
• For example, Hobbs and Norton (1996) cogently
  argue that
• restoration ecology has largely progressed on
  an ad hoc, site-and situation-specific basis,
  with little development of general theory or
  principles that would allow the transfer of
  methodologies from one situation to another.
  This is illustrated at the international level by
  the editorial by Majer Recher (1994), which
  shows little cross-fertilization of ideas between
  different localities.

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Basic Steps in Stream Restoration(after
Interagency Handbook)

• Getting organized
• Identifying the problems and opportunities
• Developing goals and objectives
• Selecting and designing restoration alternatives
• implementing, monitoring, evaluating, and
  adapting the project.

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Goals and Objectives

• Goal is more encompassing. It defines what you
  want the state of the river to ultimately look
  like. They should naturally be consistent with
  the problem/opportunity identification data
  (i.e., problem-opportunity statements).
• Objectives are more specific. Focus on specific
  factors that can be produced to achieve the
  stated goals.
• Unrealistic goals can generate unrealistic
  expectations and potential disenchantment amount
  stakeholders when those expectations are
  unfulfilled.

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Setting Goals and Objectives(Three Components)

• Define the desired condition of the future
  system.
• It represents the ideal situation for
  restoration, whether or not this reference
  condition is attainable.
• This ideal has been given the name potential
  and is considered to be the highest ecological
  condition or state that a stream can attain,
  given no political, social, or economic
  constraints (Prichard, et al., 1993).

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Setting Goals and Objectives(Three Components)

• Identify the scale of the project, and the scale
  at which impacts may impact the system.
• For all systems, watershed scale processes
  influence the river. Need to start here.
• If the channel is being disturbed upstream and
  downstream of the site, is it reasonable to
  proceed.
• How stagnate is development will the watershed
  look the same in 10 years as it does today. If
  not, how will this affect the system.

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Setting Goals and Objectives(Three Components)

• Identify constraints and issues that must be
  considered.
• These are things that constrain the methods that
  may be used in the project. They consist of both
  technical and non-technical factors.
• Technical generally related to availability of
  data, likelihood of stabilizing a given area,
  based on our current expertise with the a
  particular problem.
• Nontechnical are more numerous and readily
  recognized. May include, Political/social
  conflicting land-use or water use issues
  grazing, logging, fishing, public access, etc.
  Financial issues, Legal issues such as Permits,
  or issues regarding property ownership,
  easements, and zoning.
• Physical existing structures roads, pipelines,
  powerlines, etc.
• For contaminated rivers, also need to consider
  areas which may not have been remediated.

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Selection of Restoration Alternatives

• The alternative that is selected should
  accomplish the restoration goals and objectives,
  and, therefore, solve the identified problems
  within the limits provided by the restoration
  opportunities.
• Must always consider whether you are treating the
  causes or symptoms. Treating the symptoms may
  result in other, unwanted impacts.

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Alternative Types

• No action System will heal itself, for does not
  merit intervention.
• Nonstructural techniques broadly defined as any
  restorative method that does not involve either
  physical alterations (e.g., realignment of the
  channel, riprapping, etc.) of the river or
  construction of a dam or some other structure
  (NRC, 1992).
• Structural Intervention of the current river
  processes of form using physical materials or
  structures.

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Types of Structural Approaches

• Soft engineering refers to the use of locally
  available natural materials such as woody debris
  and alluvium. Restore to natural conditions
  using natural stuff.
• Hard engineering hydraulic engineering
  approach, which typically optimizes for one use
  (e.g., flood conveyance, drainage, etc.) and
  utilizes concrete, sheet pilings, riprap, or
  other imported materials.
• Biotechnical engineering channel or bank
  modification methods that use vegetation in a
  variety of innovative ways.

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From Interagency Handbook
17
(No Transcript)
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Willow Fences
Rock Weirs
Headcut Structures
Log/Willow Erosion Structures
Root Balls
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Cross Vane
From Rosgen, 2003
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Rosgen, 2003
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Additional Considerations to the Alternative
Selection Process

• Identification of possible alternatives that
  exist. Must include no action.
• Analysis of how cost-effective it is. Requires
  two types of data
• Estimates of the alternatives net benefits
  (output).
• Estimates of costs. More readily determined.
• Risk assessment No matter what alternative is
  ultimately selected, there is always a certain
  amount of risk that the project will fail. The
  potential for failure should be evaluated.

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Channel Design and Reference Reaches

• In some cases, it may be advantageous to entirely
  or partly reconstruct a channel from scratch.
• Channel should be constructed to transport the
  available water and sediment delivered to the
  system without causing significant erosion or
  deposition.
• Reconstructing a channel from scratch is an
  extremely complicated process, and there are
  multiple methods of attacking the problem.

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Lake Christopher Erosion Control Project (Tahoe
Basin)
Excavated Channel
Channel Breaching, 1995 Flood
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Reference Reach Approach

• Can be based on either
• Biology reach with desired biological
  conditions, which will be used as a target to
  strive for when comparing various restoration
  options.
• Geomorphology reach that serves as a template
  for the geometry of the restored channel. The
  channel morphology is transferred either exactly
  or by altering scale to fit them to reaches with
  slightly different characteristics (e.g., basin
  size).

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Use of Regional Curves
From http//www.ncsu.edu/sri
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From http//www.ncsu.edu/sri
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Problems Inherent in the Use of Reference Reaches

• Most associated with the difficulty of
  identifying suitable reference reaches.
• Must have similar geology, relief, size,
  rainfall, and land cover.
• Must have similar land-use histories
• Curves assume that bankfull is the dominant
  discharge. This may or may not be true.
• Assumes that the that hydrology and sediment load
  characteristics of the disturbed basin are the
  same as the stream to be restored.

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Stream Classification Systems(Uses)

• As a communications tool.
• Provides a framework for analyzing data. It can
  be argued that streams that fall within a certain
  class will function similarly and therefore can
  be analyzed together.
• Provides a means of understanding the variability
  that may exist for selected parameters such as
  channel size, shape, pattern and classification.
• Placing a stream of interest into a particular
  category, may allow use to gain important
  insights into how that stream or river functions.

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Disadvantages of Using a Classification Approach
in Restoration

• They are based on channel characteristics at one
  specific time the time of analysis. Therefore,
  the dynamic condition of the stream is not
  directly indicated by the classification system.
• The river response to a perturbation or
  restoration action is normally not determined
  from classification alone.
• Biological health of a stream system is usually
  not directly determined from a geomorphic
  classification system.

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Rosgen Classification
From Rosgen, 1996
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Important Comment

• Most academics will state that classification
  systems, including Rosgens, should be used
  cautiously and only for establishing some of the
  baseline conditions on which to base initial
  restoration planning.
• Interagency Handbook states, Standard design
  techniques should never by replaced by stream
  classification alone.

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Table from NRC, 1992
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From W.M. Davis to Rosgen???

• While there is a lot of talk surrounding the
  whole system, the classification system of Rosgen
  is generally applied at the reach scale. Thus,
  it draws attention away from a systems approach,
  and focuses on a specific reach.
• Represents a cookbook method that is commonly
  linked to evolutionary schemes that may or may
  not be valid for a particular stream of interest.
• Ignores that river processes are a function of
  that systems history.
• Suggests that all rivers behave the same,
  regardless of climatic/hydrologic regime,
  geology, etc. For example, commonly stated that
  it applies to arroyos as it does to any other
  type of river. This is simply incorrect.