7_Hydrologic Cycle and Water Quality

The Hydrologic Cycle & Water Quality

• Course: ESC1000C - Dr. Jackie Miranda

• Date: February 16, 2024

Agenda

• 60 Second News Update

• Hydrologic Cycle

• Water Basins and Budgets

• Running Water

• Water Quality

• Florida Water Issues 2025

Overview of Earth Sciences

• UNIT 1: Geology

• UNIT 2: Oceanography

• UNIT 3: Meteorology

• UNIT 4: Astronomy

Hydrologic Cycle

Definition

• The hydrologic cycle describes the continuous movement of water within the Earth and atmosphere.

The Earth System

• Earth is a complex system comprised of various spheres:

  • Biosphere: life forms

  • Hydrosphere: water in all forms

  • Geosphere: land/earth structure

  • Atmosphere: gases around Earth

Hydrosphere

• Formed approximately 4.5 billion years ago during the early development of the atmosphere.

• Initial water vapor likely originated from volcanic eruptions.

• Water covers approximately 70% of the Earth's surface.

• Query: What percentage is available for human consumption?

Freshwater Distribution

• 68.7% of Earth's freshwater is stored in glaciers and ice caps.

• Melting glaciers and ice caps due to global warming result in loss of this freshwater as it mixes with ocean water.

• 30.1% of freshwater is groundwater, the primary source accessed and utilized by humans.

The Movement of Water in the Hydrologic Cycle

Process

• Water evaporates from oceans, plants, and soil, entering the atmosphere.

• Returns to Earth via precipitation.

Paths of Water Post-Precipitation

• Infiltration (soaks into ground), runoff (flows over surface), evaporation, or storage as snow/glacier.

Balance of the Hydrologic Cycle

• The cycle is balanced; water movement occurs between reservoirs, with total amount remaining constant.

Energy Source

• The primary driver of the hydrologic cycle is the sun.

  • Key processes:

    • Evaporation (oceans)

    • Transpiration (land)

    • Condensation

    • Precipitation

    • Runoff

    • Infiltration

    • Groundwater/aquifers

Review Questions on Hydrologic Cycle

1. Origin of water on Earth's surface?

   • A. Volcanic eruptions

2. Primary energy source driving the hydrologic cycle?

   • C. The sun

3. Process producing water vapor from plants?

   • A. Transpiration

4. After rain falls, it may:

   • C. Infiltrate or evaporate

Water Basins and Budgets

Water Use and Distribution

• The U.S. uses 1,344 billion liters (355 billion gallons) of ground and surface water daily.

• 21% of this, or 88 billion liters (76 billion gallons), is fresh groundwater.

Surface Water Distribution

• The 100th meridian is the rough boundary between moisture-rich and arid parts of the U.S., affecting agriculture practices (necessity for irrigation).

Trends in Water Use

• Water use has decreased over the last 20 years due to:

  • Improved technologies, such as low-flow toilets and efficient agricultural practices.

Running Water

Drainage Basins/Watersheds

• A stream drains an area known as a drainage basin or watershed, controlled by elevation and gravity.

Drainage Patterns

• Types:

  • Dendritic: Most common; uniform material

  • Radial: Found on volcanic cones

  • Rectangular: Forms in jointed/faulted bedrock

  • Trellis: Alternating resistant and weak strata

Runoff vs. Infiltration

• Influenced by:

  • Rainfall intensity and duration

  • Soil moisture content

  • Soil type

  • Land slope

  • Vegetative cover

• Runoff dominates on impermeable or saturated surfaces, especially urban areas.

Aquifers

• Definition: Underground layers of rock holding groundwater.

• Aquifers can deplete faster than they refill, termed aquifer depletion.

Fluvial Processes

• Rivers significantly influence land drainage, affected by climate and human activity.

Discharge

• Defined as the volume of water flowing past a point over a certain time (Discharge = velocity x area).

Zones of a River System

1. Sediment Production: Dominant erosion area in the headwaters.

2. Sediment Transportation: Balanced transport between erosion and deposition.

3. Sediment Deposition: Occurs when rivers enter larger bodies of water.

Transportation of Sediment

• Three load types:

  • Dissolved Load: Ions from chemical weathering

  • Suspended Load: Particles sized according to the flow velocity

  • Bed Load: Larger particles transported by bouncing

Stream Channels

Types

• Bedrock Channels: Found in steep areas; stable

• Alluvial Channels: Changes shape due to erosion and deposition; includes meandering and braided streams

Meandering Streams

• Characterized by sweeping bands with significant erosion on banks with higher velocity.

Braided Streams

• Composed of diverging and converging channels, typically transporting coarse materials.

Floods

• Occurs when discharge exceeds channel capacity:

  • Regional Floods: Caused by rapid snowmelt or storms.

  • Flash Floods: Rapid rainfall leads to quick water level rise.

Flood Control Methods

• Artificial levees: Earth mounds along river banks.

• Flood-control dams: Retain floodwater.

• Channelization: Altering stream channels for increased flow rate.

• Nonstructural methods: Zoning for floodplain management.

Water Quality

Water Contamination

• Point-source: Single and definable origins (e.g., waste sites).

• Nonpoint source: Multiple, diffuse origins (e.g., agriculture).

Types of Groundwater Contamination

1. Organic Chemicals

2. Inorganic Chemicals

3. Microbial/Biological

Organic Contaminants

• Example sources: herbicides, pesticides, industrial solvents, and pharmaceutical residues.

Inorganic Contaminants

• Examples: heavy metals (lead, mercury), nutrients (nitrates, phosphates).

Biological Contaminants

• Includes harmful bacteria like E. coli; groundwater is usually safe unless linked to contaminated surface water.

Water Remediation Techniques

• Bioremediation: Using bacteria to decompose contaminants.

• Phytoremediation: Utilizing plants to absorb harmful chemicals.

• Chemical remediation: Applying chemicals for harmful material breakdown.

• Physical remediation: Filtration methods.

Pinellas County Water Quality Monitoring

Key Indicators

1. Dissolved Oxygen: Vital for aquatic life.

2. Nutrients: Monitoring is crucial to prevent eutrophication.

3. Salinity, Temperature, Bacterial Count: Essential physical parameters for water bodies.

Florida Water Issues Research Assignment

• Topics include groundwater depletion, Everglades restoration, saltwater intrusion, and runoff.

• Students are to summarize, identify causes, and propose solutions.

Upcoming Topics

• Earth Processes and Groundwater: Study on weathering, erosion, soil, and groundwater, with an update due 2/19.

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