The Hydrology of Ecological Devastation: Mountaintop RemovalValley Fill Coal Mining

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The Hydrology of Ecological Devastation
Mountaintop Removal/Valley Fill Coal Mining
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Background

• MTR/VF Coal mining flattened over 1 million acres
  
• Buried thousands of miles of streams
• Altered hydrology blamed for destructive and
  deadly flooding
• Acid mine drainage, sedimentation, etc. causing
  reduction in habitat

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Peak Flow Study

• Wiley and Brogan
• USGS

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Determination of Peak Flow

• Observed high water marks from July, 2001 flood
• Estimated Mannings coefficient
• Calculated peak flow (previous studies avg. 6.7
  error using this method)
• Calculated flow sensitivity to 10 increase or
  decrease in Mannings coefficient
• Estimates of flood-recurrence intervals based on
  published flood-frequency equations (Wiley, 2000)
  
• Valley-fill site intervals calculated as though
  they were typical streams

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Reasons for Runoff Variability

• Lesser slope on top of VF causes increased travel
  time
• Reduced permeability of VF surface decreases
  travel time and increases runoff volume
• Deforestation results in increase of runoff volume

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Issues

• If precipitation across study area were equal,
  than flood-recurrence intervals of unfilled sites
  should be equal Really?
• How does accuracy of interpretation of high water
  marks affect peak flow estimation
• Wide range of flood-recurrence intervals for
  valley fill sites mysterious synthetic
  hydrology

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The Anatomy of a VF
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Impacts of VF on Headwater Floods in Eastern KY

• J.D. Phillips
• UK

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Relative Runoff and Flow Detention Models

• Model compared VF hydrology to reference
  condition (unmined forested hillslopes with
  typical Eastern KY soils)
• Simply alter variables for new condition
• Output is ratio of situation in question to
  reference situation

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Increasing Surface Runoff

• Reduce average flow length, L
• Reduce runoff abstraction, K (infiltration
  excess)
• Reduce available water capacity, C (saturation
  excess)
• Increasing slope, S
• Reducing surface roughness, N

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More Ratios

• Infiltration Excess
• Saturation Excess
• Runoff from CN

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Ratios of Variables

• Minimum is preferred

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Runoff
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Runoff Results

• Tend to indicate that flash flooding would be
  more prevalent downstream of VFs due to
  infiltration excess runoff
• In general, results suggest that runoff response
  is likely to be increased for VF sites
• Agree with previous studies that VF streams will
  maintain higher low-flows than unaffected streams
  ecological implications?

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Precipitation Variability

• Mine companies claim variable precipitation over
  flooded area
• Analyzed two floods using radar precipitation
  images
• Images indicate storm precip totals 2 km pixels
• Placed random transects over study area (Eastern
  KY)

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Precipitation Contd

• SPF used to determine spatial dependence in storm
  precipitation patterns
• SPF indicates probability that different precip
  class will be h pixels apart
• Essentially SPFltSPF random indicates clustering
  of precip values

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Precipitation Contd

• Results indicate that spatial dependence of
  precip for two storms is high

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The Connection
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To what extent does the hydrology of a VF effect
ecology?

• Sponge effect
• Sustained baseflows during drought and increased
  baseflows year-round

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Ecological Effect Contd
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Benthic macroinvertebrate assemblages in streams
with varying flow permanenceJ.W.
FeminellaAuburn U.
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Findings

• 75 of species displayed no pattern with respect
  to stream permanence
• 7 of species found exclusively within
  intermittent streams
• However, other results indicate that assemblages
  show predictable, but subtle, relationships with
  stream permanence
• Year to year riffle permanence influence the
  structure of assemblages

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How much do VF influence stream habitat?

• Hartman, et al.
• WVU

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Findings

• No evidence for increased sedimentation
  downstream
• Increases stream conductivity
• Increases metals in streams (Na, K, Mn, Mg, Ca,
  Ni, and Fe)
• Significantly lower populations of 6 varieties of
  stream biota
• However, given the level of disturbance in
  valley fills, it is surprising how little
  differences existed between fills and reference
  stream biota

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Issues

• Deep pit mining had occurred in all of watersheds
  that Hartman studied. Reference streams?
• How does new temperature regime affect stream
  habitat?
• Fish?
• Worth studying hydrology of VFs? Too random?
• Turn off the lights?