Investigating the Linkage between Water Quality and Water Quantity in Watershed Management

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Investigating the Linkage between Water Quality
and Water Quantity in Watershed Management

• Richard L. Kiesling
• 1United States Geological Survey, Water Resource
  Division, Texas District, 8027 Exchange Drive,
  Austin, TX, 78754
• 2Environmental Science Institute, University of
  Texas, Austin, TX, 78712

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Why Evaluate Impact of Streamflow?

• Streamflow acts as a master variable
• Controls Water Residence Time
• Regulates Rates of Physical Disturbance
• Regulates Nutrient and Carbon Cycling
• nutrient uptake length a function of stream depth
  and velocity (e.g., Valett et al. 1996)
• nutrient assimilation and turnover rates a
  function of discharge (Butterini and Sabater
  1998).
• Regulates Channel Characteristics
• Hydro-geomorphology

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Water Resource Functions

• Aesthetics enhancement of property values
• Habitat fish and wildlife survival and
  reproduction
• Hydro-electric power generation
• Recreation swimming, boating, fishing
• Seafood production freshwater inflows for
  shellfish and finfish production
• Water quality assimilation of waste and
  production of safe drinking water
• Water supply Ag, Domestic, Industrial,
  Recreation

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Investigating the Linkage

• Approach
• Technical evaluation of the impact of instream
  flows on wastewater effluent assimilation
• Methodology
• Run calibrated QUAL-TX water quality model with
  alternative instream flow criteria
• Compare model output for alternative effluent
  sets under different static flow conditions

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Acknowledgments

• TCEQ
• Joan Flowers, Carter and Burgess
• TIAER
• US EPA
• Tarleton State University
• Amy Findley
• Jeff Back

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Water Quality Simulations Rio Grande

• Calibrated QUAL-TX Model
• Modified Headwater Flow
• 60 and 40 of median daily flow from Fort
  Quitman Gage 1923 through 1950 (3.6 m3/sec and
  2.4m3/sec)
• Conserved Pollutant Load
• Modeled Alternative Load Scenarios
• Increased BOD load by 20mg/L for two flow
  scenarios
• Compared Predicted Instream DO

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Rio Grande / Rio Bravo Basin
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Rio Grande Alternative Load Scenarios
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Rio Grande Alternative Load Scenarios
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Rio Grande Alternative Load Scenarios
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Water Quality Simulations North Bosque

• Used Calibrated TNRCC QUAL-TX Model
• Modified Headwater Flow
• Default Instream Flow restriction based on 60 or
  40 of median daily flow recorded at Clifton Gage
• Conserved Pollutant Load
• Modeled Alternative Load Scenarios
• Increased BOD load by 20mg/L for two flow
  scenarios
• Compared Predicted Instream DO

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BO040
BO060
BO070
BO090
NC060
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North Bosque Alternative Load Scenarios
 
 
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Downstream
Upstream
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Simulation Study Conclusions

• Maintenance of instream flows above critical low
  flows increased modeled assimilative capacity
• Potential exists for economic trade-off between
  wastewater treatment costs and instream flow to
  maintain assimilative capacity
• Integrated water resource management requires the
  simultaneous assessment of streamflow
  manipulation and assimilative capacity
• Does this apply to all constiuents?

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System Model of Nutrients and Watershed
Eutrophication

• Nutrient supply can limit algal production
• Nutrient enrichment from watershed and marine
  sources can control extent of limitation
• Control Points within watersheds dictate
  trophic-level responses to nutrient enrichment
  for example
• Frequency and magnitude of loads
• Spatial and temporal change in LULC
• Hydro modification (entrenchment, diking)

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In-stream Methods algal production

• NDS periphytometers apparatus design
• Liquid media diffusing through two-layer
  substrate
• 0.45 micron nylon barrier filter
• GFF substrate - analyzed for algal biomass or
  carbon
• Factorial Experiments factors, 1 level each,
  interaction term
• Six Sites in North Bosque River Watershed
• Nutrient media additions of 350 uM N and 100 uM
  P
• Eight replicates per treatments
• 10-14 day deployments micro and macro methods

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BO040
BO060
BO070
BO090
NC060
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Matlock Periphytometer, North Bosque River, Hico
TX
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Micro-NDS Periphytometer, North Bosque River,
Hico TX
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Conclusions Watershed Eutrophication

• Nutrient-limited periphyton primary production
  conforms to resource-consumer model of population
  growth based on resource supply rate
• Periphyton primary productivity is elevated along
  the instream nutrient concentration gradient,
  documenting a change in trophic status
• Periphyton and water-column primary productivity
  at Clifton (BO090) track mean discharge as well
  as nutrient concentration

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Micro-NDS Periphytometer Taos Ski Valley, New
Mexico
Dr. Richard Kiesling US Geological Survey 8027
Exchange Drive Austin, TX 78754 kiesling_at_usgs.go
v [phone]
Micro-NDS Periphytometer Steer Creek, Oregon
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Contact Information

• Dr. Richard Kiesling
• US Geological Survey
• 8027 Exchange Drive
• Austin, TX 78754
• kiesling_at_usgs.gov
• [phone]

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Buffalo Bayou Example

• Proposed to augment flow of Buffalo Bayou from
  upstream flood control reservoir
• Maximum annual demand for instream flow releases
  was 62,985 ac-ft per year
• WWTP alternative cost 22.1 million for
  construction and operation (2001 dollars)
• Alternatives approximately equivalent at raw
  water cost of 350 per ac-ft (2001 dollars)

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Economic Evaluation Observations

• Example illustrates the potential for benefits
  analysis associated with the maintenance of
  instream flows
• Example demonstrates the potential value of
  integrated functional analysis of water quality
  and water quantity
• Raises questions regarding costs estimates
  available for this type of planning exercise

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Water Quality Simulations Rio Grande

• Calibrated QUAL-TX Model
• Modified Headwater Flow
• 60 and 40 of median daily flow from Fort
  Quitman Gage 1923 through 1950 (3.6 m3/sec and
  2.4m3/sec)
• Conserved Pollutant Load
• Modeled Alternative Load Scenarios
• Increased BOD load by 20mg/L for two flow
  scenarios
• Compared Predicted Instream DO