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Introduction to Watersheds: Hydrology & Water Quality

Introduction to Watersheds: Hydrology & Water Quality. Watershed Academy Greg Jennings, PhD, PE jennings@ncsu.edu. "We have to teach the general public to appreciate water - clean water - both in quality and quantity. The American people take it for granted. We can't take it for granted.“

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Introduction to Watersheds: Hydrology & Water Quality

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  1. Introduction to Watersheds: Hydrology & Water Quality • Watershed Academy • Greg Jennings, PhD, PE • jennings@ncsu.edu

  2. "We have to teach the general public to appreciate water - clean water - both in quality and quantity. The American people take it for granted. We can't take it for granted.“ "We can solve many of our problems in water quality by good land management, taking care of the watershed.“ Luna Leopold, 2002 Retired Chief Hydrologist, U.S. Geological Survey

  3. 1948 Federal Water Pollution Control Act (FWPCA): "enhance the quality and value of our water resources and establish a national policy for prevention, control and abatement of water pollution" 1956 Water Pollution Control Act Amendments: allow federal government to act where health endangered 1965 Water Quality Act: enforceablewater quality standards 1972 FWPCA Amendment (“Clean Water Act”): consolidated authority in EPA with objective: “restore and maintain chemical, physical, and biological integrity of nation's waters” Goals: (1) eliminate discharge of pollutants into the navigable waters of the United States by 1985; (2) water quality that provides for the protection of fish, shellfish, and wildlife and recreation by 1983.

  4. From Webster's Revised Unabridged Dictionary (1913) : Watershed, n [Cf. G. wasserscheide; wasser water + scheide a place where two things separate, fr. scheiden to separate.] • The whole region or extent of country which contributes to the supply of a river or lake. • The line of division between two adjacent rivers or lakes with respect to the flow of water by natural channels into them; the natural boundary of a basin. Other Terms: Catchment, Drainage basin, River basin

  5. Watershed: • “Area of land that drains water, sediment, and dissolved materials to a common outlet at some point along a stream channel” • Dunne and Leopold, 1978 • Watershed form is influenced by: • Climate • Geology & Soils • Fluvial Geomorphology • Vegetation • Land Uses

  6. Watershed Functions: • Transport & Storage: • Water • Sediment • Dissolved Materials • Habitat: • Animals • Plants • Humans

  7. Water Transport & Storage • Hydrology: The study of the flow of the earth’s waters through the hydrologic cycle. • Total Water on Earth: 326 million cubic miles • 97.2% oceans • 2.15% ice caps and glaciers • .65% lakes, streams, ground water, atmosphere

  8. The Hydrologic Cycle Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.

  9. Hydrologic Cycle • The flow of water through the earth’s system, powered by gravity and solar energy. • Precipitation • Evaporation • Evapotranspiration • Surface Runoff • Stream Flow • Infiltration • Subsurface Flow • Ground Water Flow

  10. Hydrologic Responses to Urbanization Increased discharge Increased peak discharge Increased velocities Shorter time to peak flow More frequent bankfull events Increased flooding Lower baseflow Less ground water recharge

  11. Hydrograph Changes Due to Urbanization Urban Rural

  12. Sediment Transport & Storage • Flowing water does work: • Erosion • Sediment Transport • Sediment Deposition • Channel Development • Channel Adjustments

  13. Stream Corridor Longitudinal Profile Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.

  14. Sediment Sources • Land Disturbance • Channel Erosion • Bedload Transport

  15. Stream Functions • Transport water • Transport sediment • Habitat (aquatic & terrestrial) • Recreation • Aesthetics • Safe Water Supply

  16. Stream Corridor Lateral Profile Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.

  17. Stream Channel Cross-Section Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.

  18. Ephemeral Perennial Intermittent

  19. Strahler Stream Order Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.

  20. size and shape of the channel Stream Channel Morphology Influenced by: Watershed area Land use and land cover Soils and geology Topography Climate Human impacts (intentional or not)

  21. Terrace Stream Components Floodplain Right Bank Left Bank Thalweg Streambed Downstream

  22. Stable Stream transports the water and sediment produced by its watershed, such that over time it maintains its dimension, pattern, and profile, while neither degrading nor aggrading Rosgen, 1994

  23. Water Quality Influenced by: Geology & Soils Land Use Pollution Sources Flow Conditions

  24. Stream Impairment Causes (EPA, 2000) Sediment Pathogens Nutrients Metals Dissolved Oxygen Habitat Alterations Temperature pH Impaired Biology Pesticides Flow Alterations Mercury

  25. Where Does PollutionCome From? Nonpoint Sources Agriculture Stormwater Point Sources Forestry Construction

  26. Point Sources Wastewater Treatment Plants (WWTPs) Industrial Plants Sources of organic waste, nutrients, pathogens, metals, chemicals Regulated by federal Clean Water Act (EPA) National Pollutant Discharge Elimination System (NPDES) Permitted limits of discharges Regular monitoring & inspections Fines for permit violations

  27. Agriculture: Livestock Production Sources of nutrients, pathogens, organic waste, habitat loss Regulated by numerous state & federal laws Farm Bill Clean Water Act State & Local Regulations

  28. Agriculture: Crop Production Sources of sediment, nutrients, pesticides, habitat loss Regulated by numerous state & federal laws Farm Bill Clean Water Act Pesticide Regulations Nutrient regulations

  29. Forestry Commercial Timber Production Small Woodlot Forestry Sources of sediment, nutrients, habitat loss Regulated by Sediment Pollution Control Act Forestry BMPs required Technical assistance from NC Div Forest Resources Financial incentives for forest management

  30. Urban Stormwater & Construction NC population doubles every 40-50 years Urbanized area doubles every 20 years Sources of sediment, nutrients, pathogens, metals, chemicals, pesticides, habitat loss Regulated by Clean Water Act Phase 1 and 2 NPDES regulations Limits on development BMPs required

  31. Land Development Impacts • Increased Imperviousness • Increased Runoff • Increased Pollutants • Impacts to Streambanks • Erosion/Sedimentation

  32. Stream Condition Related to Impervious Surface Good Fair Poor Protected Impaired Urban Drainage Network Degraded Source: Center for Watershed Protection

  33. ChallengesWater quality problems: • Watershed-scale • Result from many diffuse sources • Difficult to diagnose • Related to local land uses

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