Engineering Geology Quiz 7

Steps of the Hydrologic Cycle

Precipitation, Runoff, Evaporation, Transpiration, and Infiltration

Capillary Fringe

Where saturated zone starts

Vadore

AKA unsaturated zone, directly underneath the subsurface boundary

Overland Flow

When precipitation rate exceeds infiltration rate

Interflow

Horizontal movement of infiltrated water in the unsaturated zone

Base Flow

Groundwater that is discharging into streams

Drainage Basin

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

Hydrograph

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

Flood Control

Battle between natural processes and human activities; study past and look to future

Erosion and sedimentation

Local scour can undermine foundations

Groundwater

Provides about 2/3 of freshwater resources to drinking water, agriculture, and industry

Porosity

Total volume of pore spaces

Permeability

Ease of water flow due to pore interconnectedness

Aquifer

Sediment or rock that transmits water easily

Aquitard

Impermeable or low permeability sediment or rock that hinders water flow

Unconfined

An aquifer that intersects the surface

Confined

An aquifer below an aquitard; isolated from the surface

Darcy’s Law

Equation that predicts the volume of water passing through an aquifer at any given time

Pumping

Drawdown where water table levels drop

Cone of depression

Downward pointed conical shaped water surface; deepest near the well and flattens with distance

Reasons for groundwater changing naturally

Precipitation, changes in seasons, and tidal regions

Springs

Locations of natural groundwater discharge

Reasons for springs forming

Ground surface intersects the water table; strong permeability contrasts; seepage where a perched water table intersects a slope

Groundwater Problems

Groundwater depletion; reversing flow direction; pore collapse and land subsidence

Exclusion

Use low permeability cut-off walls around excavation

Sea wave cause

Frictional drag of moving air currents on water surface

Sea wave movement

Only the water surface and its near sub-surface are disturbed by wind

Sea waves fetch

The range to generate and promote waves

Oscillatory waves

No long distance movement, occurs in far offshore open water surface, wave energy is supplied by the wind

Translational waves

Whole water mass is moving, occurs near offshore in shallow water surface

Crest

Top of wave

Trough

Bottom of wave

Breaking waves

When oscillatory waves transition into translational waves at depth of d=L/2

Waves erosion causes

Mechanical impact and hydraulic pressure; abrasion of loose materials

Dunes

Depositional features caused by wind

Long-shore

Currents and waves transport sediment and deposit it to areas of low energy

Groins

Extend beach areas and retard erosion

Jetties

Extend river banks to protect river mouths, tidal inlet, and harbor entrances; directs or confines the river flow into the sea to reduce shoaling

Megatsunami

Large wave created by a large, sudden displacement of material into a body of water