Hydrologic Functions of Headwaters Streams and Riparian Zones Implications for Waste Application in

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Hydrologic Functions of Headwaters Streams and
Riparian Zones Implications for Waste
Application in Forests

• Dr. James D. Gregory
• Department of Forestry
• NC State University

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Topics

• Forests the baseline of water quality
• Headwaters streams and their hydrologic role in
  watersheds
• The runoff process components, variability
  among stream types, impacts of catchment
  characteristics, large storm events the
  pollutant movers and shakers
• Ecological role and functions of riparian zones
  in stream corridors
• Maximizing hydrologic functions - BMPs

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Forest Water Quality - The Baseline

• Best water quality comes from undisturbed
  forested watersheds
• Next-best from well-managed forests
• Forests are nutrient sinks -
• Precipitation inputs
• Overland flow or subsurface flow inputs
• Animal inputs
• Mineral weathering inputs
• Fertilizers and waste applications

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Annual Input/Output Fluxes in a Headwater Stream
in Shenandoah National Forest
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Average Annual Water and Inorganic N Budgets for
Coweeta Reference Watersheds
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Land Use in Three Study Watersheds in Eastern
North Carolina
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Water Quality in Three Study Watershedsin
Eastern North Carolina
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Mean Annual Suspended Sediment Yieldin the North
Carolina Piedmont
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Mean Nitrate-N Concentration in Streamflowfrom
NC Piedmont Watersheds
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Management Implications

• Extent and distribution of forests in a watershed
• Proportion of forested area in a watershed that
  is in a disturbed state
• Distribution and size of disturbed areas
• Use of BMPs
• In waste applications consider not only the
  nutrient loads on the forested catchment, but the
  contributions to loads in the larger watershed
  TMDLs are here to stay!!

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Water Quality from the Hofmann Forest,
NCIntensively Managed Coastal Plain Forest
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Ecological Functions

• Natural processes what ecosystems do
• Scientists focus on individual functions or
  groups of functions in order to study them and
  learn to influence them for human benefit
• May be categorized in many different ways
• Hydrologic
• Geochemical
• Biologic

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Hydrologic Functions

• Processes related to water at the earths surface
• Rainfall input to the surface
• Infiltration into the soil
• Storage and movement of water in the soil
• Runoff to streams
• Transport of sediment and dissolved constituents
  in runoff

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Geochemical Functions

• Processes related to chemical reactions
• Rock weathering and release of soluble compounds
  calcium, magnesium, sodium, iron, manganese
• Chemical reactions in the soil water
• Chemical reactions in streams
• Nutrient cycling by plants uptake from the
  soil, temporary storage in foliage, release back
  to the soil by organic matter decomposition

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Biological Functions

• Any processes related to the presence and
  activities of living organisms

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Ecological Functions and Pollutants from Waste
Applications

• Know the functions that affect stability,
  mobility, and processing of nutrients, metals,
  etc. in the waste
• Manage the waste application rates and locations
  to maximize the functions that retain pollutants
  onsite
• Manage the forest to maximize the functions that
  retain pollutants onsite

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Watershed

• Also drainage basin or catchment
  topographically delineated area that is drained
  by a stream system land area within which all
  precipitation input drains to one stream outlet,
  called the mouth a natural hydrologic system
  within which inputs, outputs, storage, and fluxes
  of water and associated dissolved and suspended
  materials can be measured.

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Headwaters Stream

• Refers to the first order and second order
  streams of a watershed without regard to location
  in the watershed or their classification as
  intermittent or perennial.
• Headwaters streams are where the hydrologic
  action occurs

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What is a Stream? Regulatory definitions for
riparian buffer rules

• Stream natural body of concentrated flowing
  water in a natural low area or natural channel on
  the land surface.
• Ditch or canal - man-made channel constructed for
  drainage purposes, other than modified streams
  is typically dug through inter-stream divide
  areas flow may be perennial, intermittent, or
  ephemeral may exhibit hydrological and
  biological characteristics similar to perennial
  and intermittent streams but are not streams.

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Perennial Stream

• Contains water year round during a year of normal
  rainfall (defined as the most recently available
  30-year annual and seasonal means from the
  National Weather Service) flow occurs in a
  well-defined channel the aquatic bed is located
  below the water table for most of the year
  groundwater is the primary source of water, but
  the stream also carries stormwater runoff
  exhibits the typical biological, hydrological,
  and physical characteristics commonly associated
  with the continuous conveyance of water.

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Intermittent Stream

• Contains water for only part of the year,
  typically during winter and spring when the
  aquatic bed is below the water table flow occurs
  in a well-defined channel groundwater is the
  primary source of water, but the flow may be
  heavily supplemented by stormwater runoff often
  lacking the biological and hydrological
  characteristics commonly associated with the
  continuous conveyance of water

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Ephemeral Stream

• Carries only stormwater in direct response to
  precipitation water flows only during and
  shortly after precipitation events may or may
  not have a well defined channel the aquatic bed
  is always above the water table stormwater
  runoff is the primary source of water typically
  lacks the biological, hydrological, and physical
  characteristics commonly associated with the
  continuous or intermittent conveyance of water.

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USGS Map Accuracy An Example
Stream lengths (mi) in a headwaters catchment
compared to that depicted on the USGS 124,000
map (Lake Wheeler Quadrangle, NC).
 
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Hydrologic Role of Headwaters Streams

• Most of the land area of the humid US drains to
  them
• Headwaters streams are bordered by a major
  portion of the total length of riparian zones
• Headwaters streams are the piping network for
  transport of pollutants from the land to rivers
  and estuaries

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Stream Network Parameters  


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The Runoff Process

• The hydrologic processes by which rainfall
  becomes streamflow
• Runoff components
• Channel precipitation
• Overland flow
• Interflow
• Stormflow
• Base flow

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Channel Precipitation

• refers to precipitation that falls directly onto
  the water surface of the stream network, and, of
  course, represents the most rapid mode of
  delivery of rainfall to the stream is a very
  small percentage of total streamflow

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Overland Flow

• refers to precipitation that runs over the land
  surface to a stream without ever infiltrating at
  any point along the flow route is the next most
  rapid mode of delivery of rainfall to a stream
  is easily identified with the rainfall event that
  generates it (new rain). The relative volume and
  velocity of overland flow is controlled by soil
  hydraulic conductivity (mean velocity of
  subsurface flow), soil infiltration capacity,
  surface detention storage, surface roughness, and
  slope gradient.

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Interflow Preferential flow

• refers to relatively rapid subsurface flow of
  water during and shortly after a rainfall event
  is the third most rapid mode of delivery of
  rainfall to a stream is unsaturated flow through
  large pores and cracks in the soil is an
  addition to streamflow that is also easily
  identified with the rainfall event that generates
  it (new rain). The relative volume and velocity
  of interflow is controlled by the subsurface
  character of the soil (texture, structure,
  profile horizons, total volume of macropores,
  size and connectivity of large pores in the
  soil), the soil infiltration capacity, and slope
  gradient.

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Stormflow

• is the combination of channel precipitation,
  overland flow, and interflow that produces a
  significant rise in streamflow during and for
  some time after a rainfall event ( Figure 5).
  The term stormflow is commonly used in
  reference to the increased stream flow resulting
  from a storm event and also is used to refer to
  the overland flow during a storm event.

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Baseflow

• is the sustained flow that occurs in a stream
  between rainfall events the water cannot be
  identified with a particular rainfall event (old
  rain) the water is supplied by slow unsaturated
  drainage from the soil to the water table and
  saturated drainage of ground water to the stream.
  Base flow is controlled by the total volume of
  water stored in the landscape adjacent to the
  stream, unsaturated soil hydraulic conductivity
  in the soil moisture zone, saturated hydraulic
  conductivity in the groundwater zone, and the
  hydraulic gradient in the groundwater zone to the
  stream.
•  

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Stormflow Accounts for Most of Pollutant
Transport to Streams !

• All erosion and sediment transport to streams
  most of that on an annual basis occurs during the
  few largest storm events
• Potential pollutants are flushed from the soil
  and transported to streams
• Microorganisms
• Soluble inorganic compounds
• Soluble organic compounds from organic matter
  decomposition
• Anthropogenic toxics

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The Runoff Process Variation With Relief

• Moderate to high relief dominant process in
  stormflow is interflow as preferential flow
  overland flow component depends on impervious
  surface, infiltration capacity, and soil
  permeability
• Low relief dominant process in stormflow is
  saturated flow rainfall infiltrates vertically,
  water table rises, hydraulic gradient to stream
  increases very high rates of subsurface lateral
  flow in the litter, root mat, and A horizon.

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Ecological Role of Riparian Zones

• Effects on Stream Water Quality

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Riparian Zone

• Riparian zone - land area transitional between
  terrestrial and aquatic ecosystems in which the
  ecological functions of the land are influenced
  by proximity to water and the ecological
  functions of the water are influenced by
  proximity to land. Zone of transfer between the
  land and a water body.

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Source Area for Streamflow

• Natural forested ecosystems subsurface flow to
  riparian zone, discharge from upstream -
  ephemeral streams!!!!
• Agricultural ecosystems greater proportion of
  stormflow is overland flow, ephemeral streams in
  fields
• Suburban urban overland flow is dominant,
  pipe or ditch flow through the riparian zone

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Removal of Dissolved Nutrients from Runoff

• Maximal removal occurs with subsurface flow
• Phosphorus most is adsorbed to sediment
• Nitrogen most removal occurs in soil that has
  combination of aerobic and anaerobic zones
• Aerobic NH4 to NO3
• Anaerobic NO3 to N2

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Nitrate Concentrations in Ground Water Under
Riparian Forests
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Sediment Removal from Overland Flow

• Infiltration to convert overland flow to
  interflow
• High surface roughness (litter, large woody
  debris, ground level vegetation) - slows
  velocity of overland flow, promotes sedimentation

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Effects of Riparian Buffers on Reductions of
Sediment and Nutrients from Field Runoff
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Tall, Deep Rooted Woody Vegetation

• Root systems help maintain channel stability and
  limit rates of bank erosion
• Contributes litter (fine organic matter) to
  stream food chain key component of food chain
  in headwaters streams
• Contributes coarse woody debris structure in
  stream, contributes to habitat diversity and
  quality
• Shading riparian zone soil and the stream to
  maintain the natural stream temperature regime

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Ecological Role of Headwaters Stream Channels

• Biological and chemical processes remove
  nutrients from streamflow
• Exported organic matter contributes to food chain
  support downstream
• Main source of water to the major streams and
  rivers - high quality water or polluted water

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Principles of Waste Application BMPs

• Quality of the main receiving stream
• Distribution within the watershed
• Soil hydrologic properties and functions
• Distribution within the headwaters stream
  catchment
• Stream buffers

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Quality of the Main Receiving Stream

• Stream classification http//h2o.enr.state.nc.us
  /csu/swcfaq.html
• Red Flags not supporting or partially
  supporting , stream on state 303d list, water
  supply watershed, nutrient sensitive waters, high
  quality waters, outstanding resource waters

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Distribution Within the Watershed

• Consider land uses and distribution of land uses
• Total assimilation capacity of the watershed for
  the pollutants to be applied

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Soil Hydrologic Properties and Functions

• Minimize impacts on soil infiltration and
  percolation capacity
• Concentrate traffic on few as possible access
  roads
• Keep traffic away from streams
• Control overland flow from compacted areas

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Distribution Within the Headwaters Stream
Catchment

• Know the stream network!!!
• Apply waste only on soil water recharge areas
  -Ridgetop, upper slope, and midslope positions
• Avoid application of waste on soil water
  discharge areas lower slope positions close to
  streams, slope wetlands, ephemeral and
  intermittent streams
• Avoid application on areas of compacted soils
  unless there is ample area of high infiltration
  capacity to receive overland flow prior to
  reaching a stream

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Stream Buffers

• Buffer all streams !!!

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Summary

• Know the watershed and the main receiving stream
• Maximize the natural hydrologic functions of the
  forest
• Know the stream network on the site
• Buffer all streams