GEOL 350: Surface Hydrology Quiz

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Questions and Answers

What does a hydrograph primarily measure?

Temperature variations over time

Types of vegetation in a catchment area

Rate of flow of a watercourse over a time period (correct)

Amount of sediment transported by a river

Which of the following components contributes to stormflow in a hydrograph?

Evaporation from water surfaces

Groundwater seepage

Run-off from precipitation (correct)

Water released from reservoirs

What is indicated by peak discharge on a hydrograph?

The lowest level of river flow during dry conditions

The average flow of the river over time

The initial flow before any rainfall occurs

The maximum flow of the river following a precipitation event (correct)

What shape does a typical hydrograph take, and why?

Variable curve, showing changes in flow after precipitation events Signup and view all the answers

What is the role of stream gauges in the context of hydrographs?

To measure stream height and velocity at various stages Signup and view all the answers

What is the primary focus of hydrogeology?

The study of water's interaction with geological formations Signup and view all the answers

What does the term 'water balance' refer to in the hydrologic cycle?

The calculation of precipitation against evaporation and runoff Signup and view all the answers

How are gaining streams characterized?

By having more water entering from groundwater than leaving Signup and view all the answers

Which term best describes the ability of a material to transmit water?

Permeability Signup and view all the answers

What typically characterizes a floodplain?

A region that is often flooded during significant flood events Signup and view all the answers

What is a hydrograph primarily used for?

To represent river discharge over a specific time period Signup and view all the answers

Which of the following represents an area where groundwater naturally emerges at the surface?

Natural spring Signup and view all the answers

Which of the following best describes the role of sediments in floodplain ecosystems?

Sediments provide fertile land ideal for agriculture. Signup and view all the answers

What sediment characteristics are most commonly found in the headwaters zone of a river?

Steepest gradient and braided channel pattern Signup and view all the answers

Which statement best describes the transfer zone of a river?

Receives sediment and features a meandering channel Signup and view all the answers

In which zone does the deposition of sediments primarily occur?

Deposition Signup and view all the answers

What effect does sand grain size between 0.2 – 0.5 mm have on stream processes?

It is most easily eroded Signup and view all the answers

What is a key feature of the braided channel pattern found in the headwaters zone?

Multiple intertwining streams Signup and view all the answers

Why does a delta typically form at the base of a river?

Because sediment is deposited at the river’s mouth Signup and view all the answers

What differentiates steady stream flow from pulsed stream flow during a flood?

The consistency of water flow and velocity Signup and view all the answers

Which zone of a river is least associated with significant erosion?

Deposition Signup and view all the answers

What does baseflow indicate about streamflow during periods of little precipitation?

It provides a constant contribution. Signup and view all the answers

How can flood predictions be made according to the principles of river flow hydrographs?

Using the formula Discharge = Area x Velocity. Signup and view all the answers

What is a characteristic of a braided channel in a river?

Rapidly changing course. Signup and view all the answers

What is the primary purpose of Flood Inundation Maps?

To indicate areas at risk for different size floods Signup and view all the answers

Which method of flooding occurs when a river overtops its banks?

Overland flooding Signup and view all the answers

What effect does urbanization generally have on streamflow rates during precipitation events?

It increases stormwater runoff due to impervious surfaces. Signup and view all the answers

Flood Hazard Mapping is primarily managed by which governing body in Alberta?

Government of Alberta Signup and view all the answers

During the summer of 2013, when did peak rainfall occur in relation to peak discharge?

Peak rainfall occurred earlier than peak discharge. Signup and view all the answers

What factor significantly alters the hydrology of urban streams?

Replacement of natural vegetation with impervious surfaces. Signup and view all the answers

What does the term 'floodway' refer to in Flood Hazard Mapping?

High-risk areas for flooding Signup and view all the answers

Which scenario is most likely to cause localized flooding?

Exceeding stormwater drainage capacity Signup and view all the answers

What was one of the notable characteristics of the 2013 flood at Exshaw Creek?

It featured temporary channels with a high sediment load. Signup and view all the answers

Which of the following statements best explains the hydrological impact of urbanization on infiltration?

Infiltration decreases due to impervious surfaces. Signup and view all the answers

Which of these sources is associated with groundwater flooding?

Basement flooding due to rising water tables Signup and view all the answers

What is the significance of the 1:100 flood return period in Flood Hazard Mapping?

It represents the likelihood of floods occurring in a hundred years Signup and view all the answers

What is the role of the Flood Awareness Map Application?

To display interactive flood risk information Signup and view all the answers

What are some measures included in flood hazard mitigation?

Monitoring winter snowpack and weather events Signup and view all the answers

What is the purpose of the Springbank off-stream reservoir?

To divert water from flooding the Elbow River Signup and view all the answers

Which of the following describes a floodplain?

A region periodically inundated by river floods Signup and view all the answers

What is a significant ecological benefit of river floodplains?

They support unique and diverse ecosystems Signup and view all the answers

Which component is NOT a part of flood mitigation infrastructure?

Increasing the floodplain area Signup and view all the answers

What function does a flood recurrence interval serve?

It predicts how often floods will occur in a specific area Signup and view all the answers

What role do reservoirs play in flood management?

They store floodwaters to reduce downstream impacts Signup and view all the answers

How does riparian restoration contribute to flood management?

By strengthening river banks against erosion Signup and view all the answers

Why is monitoring stream discharge important in flood mitigation?

It helps predict flooding events Signup and view all the answers

Which type of ecological feature developed in floodplains is critical for groundwater?

Extensive, shallow, unconsolidated aquifers Signup and view all the answers

Study Notes

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)

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Description

Prepare for the GEOL 350 quiz focused on surface hydrology and hydrogeology concepts. This quiz covers key aspects such as the hydrologic cycle, groundwater dynamics, and the interplay between rivers and floodplains. Test your understanding of essential terms and processes integral to hydrology.