Comprehensive Water, Coastal, and Slope Mass Movements Concepts

Water Table

Subsurface Boundary

Capillary Fringe

Zone above the water table where water is held by capillary action

Vadose Zone

Unsaturated zone above the water table

Overland Flow

Type of runoff where water flows over the land surface; precipitation rate exceeds infiltration rate.

Saturated Zone

Area where all pore spaces are filled with water

Interflow

Horizontal movement of infiltrated water in the unsaturated zone

Base Flow

Groundwater that is discharging into a stream

Drainage Basin

Area of land that drains all stream and rainfall to a common outlet

Hydrograph

Graph showing discharge on the y-axis and time on the x-axis

Gage Height

Level of water in a stream

Discharge

Volume of water passing through a given point over time

Porosity

Total volume of pore spaces in a material

Permeability

Ease of water flow due to pore interconnectedness

Aquifer

Sediment or rock that transmits water easily. Ex: permeable sandstone, sand/gravel

Aquitard

Impermeable or low permeability sediment or rock that hinders water flow. Ex: Clays, Shale

Unconfined Aquifer

Aquifer that intersects the surface

Confined Aquifer

Aquifer below an aquitard, isolated from the surface

Darcy's Law

Equation that helps predict discharge volume of water over time

Pumping Drawdown

Where the water table level drops due to pumping

Cone of depression

Fetch

The range to generate and promote waves. Larger Surface area of water = Larger Fetch = Larger waves

Oscillatory Waves

- Waves where water mass oscillates without long-distance movement

- usually occurs in far offshore open water surface

- 10 to 20 seconds

- Wave energy is supplied by wind; pushes against the wave crest (frictional drag in water surface)

Translational Wave

- Wave where the whole water mass is moving

- near offshore, shallow water surface

Mass Movements

Geological processes that occur naturally and long-term

Slope Movements

Engineering emphasis on short-term slope failures

Factor of Safety (FS)

Ratio of resisting force to driving force: critical measure: FS < 1 indicates instability, FS = 1 indicates impending failure, and FS > 1 indicates stability.

Sea Waves

Caused by frictional drag of moving air current (wind) on the surface

Movement

only the water surface & its near sub-surface are disturbed by wind

Groins

structures built to extend beach areas and reduce erosion by interrupting longshore currents (usual length is 30-50m).

Jetties

built to protect river mouths, extend river banks, and direct river flow into the sea to reduce shoaling (preventing sediment buildup).

Agents that cause mass movements

Gravity, Running water (wave erosion), wind, Tectonic processes (earthquakes, tsunamis), slope or gradient, and glaciers

slope instability

engineering; both materials and mechanisms of failure

landslide

collective term; most slope failures

Slip (sliding)

Mass movement depending on resisting and driving forces. FS < 1 indicates instability, FS = 1 indicates impending failure, and FS > 1 indicates stability.

Slump

type of mass movement; rotational landslide, characterized by the movement of soil or rock as a mass along a curved, spoon-shaped failure surface.

Slope failure

type of slump; weak near surface material

Toe failure

type of slump; extended slope

Base failure

type of slump; flat weak zone of depth

Falls

-type of slope movement; abrupt movement of geological material

- rock/soil mass travels most of the distance in the air

- movement occurs by free-fall, bouncing or rolling.

- strongely influened by:

Gravity

Mechanical + chemical weathering

Presence of interpose water

Topples

Type of slope movement;Blocks of rock/soil topples over

- also knoun as overturning or upside faling down

Slides

Type of slope movement; distinct zone of weakness separating the slide material

From more stable undrlying material

- translational

- rotational

Lateral Spreading

Type of slope movement;

Distinctive- occurs on gentle slopes or even flat terrain

lateral extensions accompanied by shear or tensile fractures

• Triggered by rapid ground motion

• Loses shear strength → liquefaction

Flows

Type of slope movement;

- Creep flow: interceptibly slow, steady, downward movement of slope forming rock/soil.

• indicated by: - curved tree trunks, bent fences or retaining walls

• tilted poles

• Small ripples or ridges in soil

- Debris flow: >80% parties are > 2mm

- Mud/Earth: 80% Particles are< 2mm (sand,silt, clay), hourglass shape

Body waves

travel through the Earth's interior, including P-waves (primary waves) and S-waves (secondary waves).

P wave (primary wave)

P waves are compressional and can travel through solids and liquids

- fastest kind of seismic wave

- sometimes animals can feel seismic waves

- 330 m/s, in air, 1450 m/s in water, 5000 m/s in granite

S waves (secondary waves)

S-waves can only travel through solids.

Surface Waves (Rayleigh and Love waves)

travel along the Earth's surface and are responsible for most earthquake damage; lower frequencies than body waves

Rayleigh wave

rolls along the ground like ocean waves

most shaking felt is due to rayleigh waves

Love Wave

fastest surface wave & move side to side

entirely horizontal motion

Direct Current Resisitvity

measures the resistivity of geological materials to electric current, providing insights into subsurface conditions. Applied electric current by using electrode

Graphite: 10^-6 ohm-meter, Quartzite: 10^12 ohm-meter

Dry material has higher resistivity than wet

Electromagnetic method

Electromagnetic methods apply electromagnetic fields to gather rapid data about subsurface materials, though they may lack accuracy compared to resistivity methods.

An area of land that drains all streams and rainfall to a common outlet is called?

Watershed

What does a hydrograph display?

Flow rate in a stream over time

Fetch is ___.

The range up to which longshore drift exists

The waves strike the shoreline at an oblique angle, causing back and forth deposition of sediments, and leading to a general current referred to as ___.

Longshore Drift

Which coastal engineering structure is used to expand the riverbank as it enters the ocean?

Jetty

An extremely slow type of mass movement, commonly indicated by curved tree trunks or bent fences, is referred to as:

Creep

When designing buildings resistant to earthquake, which of the following properties is considered an important design criteria?

Peak ground Acceleration

One of the engineering hazards commonly seen in limestones is ____.

Sinkholes

The surface location for a below-surface earthquake is called?

Epicenter

What waves are responsible for causing most damage?

Surface Waves