GEOL 350: Surface Hydrology Quiz

GEOL 350: Hydrology/Hydrogeology

• Course offered at SAIT
• Focuses on hydrology and hydrogeology

Surface Hydrology (Rivers, Stream Processes)

• Tuesday, January 14, 2025
• Schedule: Quiz, Slides (part 1), Break, Activity (Flood Hazard Mapping for Calgary), Break, Slides (part 2, flood mitigation), Homework (Unit 2 readings)

Unit 1: Key Concepts in Hydrology

• Learning Objectives:
  • Define hydrogeology as a branch of hydrology
  • Explain the hydrologic cycle and water balance concept
  • Describe how groundwater relates to the hydrologic cycle
  • Describe rivers as dynamic systems and interpret hydrographs/calculate flood return periods
  • Identify recharge and discharge areas, and surface water/groundwater interaction
  • Differentiate gaining/losing streams and natural springs
  • Define key terms: porosity, permeability, transmissivity, storativity, and hydraulic conductivity

Valleys vs. Floodplains

• Floodplains are areas typically covered by water during high floods
• Confined valley settings have no floodplains
• Partly-confined settings have discontinuous floodplains
• Laterally unconfined settings have continuous floodplains along channel banks

Sedimentation During Flooding

• Streams deposit finer sediments further from the channel
• Coarsest sediments are deposited nearer to the channel edge
• Natural levees form from repeated flooding

Abbotsford BC Flooding (Nov 2021)

• Fine river sediments in floodplains are ideal for agriculture and often have towns/cities
• This was experienced during the flooding of the Fraser River

Stream Longitudinal Profile

• Dominant characteristics of three zones (headwaters, transfer, deposition) are described.
  • Headwaters: steepest gradient, sediment erosion, braided channels
  • Transfer: sediment receives, meandering channels, wide floodplains
  • Deposition: shallow gradient, deposits of sediments, highly sinuous channels

Stream Table Model

• Video available online (https://www.youtube.com/watch?v=7StgdcPwzms)
• Shows difference between steady and pulsed stream flow (floods)

Particle Erosion and Deposition

• Hjulström-Sundborg diagram shows relationships between particle size and flow velocity during erosion, transport, or deposition.

A Delta Formation

• A delta forms at the river's mouth where it enters a standing body of water.

Hydrographs

• A hydrograph shows how a watercourse responds to precipitation over a period.
• Shows rate of flow (discharge)
• Also often includes precipitation as a bar graph.
• Calculated as area x velocity
• Major streams have stream gauges measuring height (depth) & velocity at various flow stages.
• Channel dimensions (width, water depth) are necessary to calculate channel area.

Interpreting a Hydrograph

• Components of streamflow include:
  • Stormflow: precipitation/snowmelt entering the channel quickly.
  • Baseflow: constant contribution from groundwater

River Flow Hydrograph

• Predicts floods based on precipitation amounts and lag time to peak discharge

2013 Flood at Exshaw Creek

• Described as a braided channel with high sediment load and unstable temporary channels.

2013 Calgary Flood

• Describes the significant flooding in the Calgary area.
• Interactive map resources are provided to explore the affected areas.

Human Impacts on River Planforms

• Calgary's river flood stories shows the effects of development on flood plains from historical maps to present data.

Effects of Urbanization

• Stormwater runoff increases after precipitation events due to impervious surfaces in urban areas.

Types of Flood Mapping

• Presents flood inundation maps and hazard mapping that use local berms and different sized floods.
• Presents interactive mapping tools (https://floods.alberta.ca etc) for flood awareness and different flood maps used by city and government agencies

Types of Flood Mechanisms

• Explains overland flooding, sewer back ups, and groundwater flooding including locations that are at higher risk of flooding and protection measures

Water Tubes

• Briefly addresses water tubes to mitigate flood impacts.

Activity

• Activity details are found in BrightSpace, specifically for Unit 1: Calgary Rivers and Floods
• Interactive websites are to be used regarding inundation, flood recurrence, and flood hazard.

Calculating Flood Recurrence Intervals

• Calculates recurrence intervals to assess flood probability, particularly for events on the Bow River at Calgary.
• Explains the 100 year trend of peak discharges, with a focus on the major flood events.

Reducing the Hazard of River Flooding

• Flood Mitigation techniques include:
  • Mapping flood plains and limiting development in those areas.
  • Installing flood berms.
  • Monitoring winter snowpack.
  • Measuring and monitoring stream discharge.
  • Educating the public.

Mitigation Infrastructure for Floods

• Reservoirs and flood barriers to mitigate flood impacts.

Importance of River Floodplains

• Explains the importance of river floodplains for storage, sediment, habitat, migration and groundwater
• Importance to the ecology of the area

Key Terms

• A list of various river-related terms for study

Homework

• Readings and quiz to complete before the next class (Tuesday, January 21)