Hydrology Unit Test Study Guide

Basics

  • Hydrology is the study of Earth’s waters. (Oceans, lakes, rivers, streams, etc…)

The Water Cycle

  • The water cycle is the process by which water recycles itself on Earth
  • Heat from the sun causes fresh water to evaporate from the oceans, leaving the salt behind. This evaporated water condenses to form clouds. Fresh water falls from the clouds to Earth’s surface as rain, snow, sleet, or hail. This constant recycling of water is called the water cycle.
  • There are three steps to the water cycle
  • Evaporation- Liquid turns to gas (water to water vapor)
  • Condensation- Gas turn back to liquid in the clouds
  • Precipitation- Any form of water (rain, sleet, snow, hail) that falls from the clouds
  • Transpiration is the process where water evaporates from plants and trees.

Distribution of Earth’s Water

  • The Earths surface is covered mostly with water- 70%-71%
  • Of all water on Earth 97% is salt water/oceans
  • Only 3% of water on Earth is fresh water
  • Of that small amount of fresh water on Earth, we cannot use most of it because it is locked in icecaps and glaciers.
  • Of the 3% of fresh water...2.1% of it is frozen which only leaves .9% of water on earth to be used by humans.
  • Salinity in oceans

Define:
Amount of salt dissolved in the water – usually listed as a percent or parts per 1,000 / Why are oceans salty?
Runoff has gathered minerals from the soil over millions of years and deposited it in the oceans / Percentage of salt:
3.5%
Most common solid:
Sodium chloride / Factors that affect salinity
Evaporation - up
Influx of fresh water-down
Formation of ice-up
Precipitation -down

Water Underground

  • Water moves underground after it rains and fills up the spaces in between the layers of rock
  • Any underground rock layer or sediment that holds water is known as a aquifer
  • People obtain water from an aquifer by drilling a hole into the rock and installing a well to remove it.

Ocean Floor Topography

  • We study the ocean floor with a device known as sonar which uses sound waves

Ocean Floor Features:

Abyssal plain- very level area of the deep ocean floor, usually lying at the foot of the continental rise.

Active continental margin- usually narrow and consisting of highly deformed sediments. They occur where oceanic lithosphere is being sub ducted beneath the margin of a continent.

Continental margin- portion of seafloor continents. Includes shelf, slope and rise.

Continental shelf- gently loping surface at submerged portion of the continental margin, extending from the shoreline to the continental slope.

Continental slope- steep gradient that leads to the deep ocean floor and marks seaward edge of the continental shelf.

Continental rise- gently sloping surface at the base of the continental slope.

Continental volcanic arc- mountains formed in part by igneous activity associated with the subduction of oceanic lithosphere beneath a continent.

Deep ocean trench- the portion of seafloor that lies between the continental margin and oceanic ridge system.

Guyot- a submerged flat topped seamount.

Mid ocean ridge- along well developed divergent plate boundaries the seafloor is elevated forming a broad linear swell.

Ocean basin floor or deep-ocean basin- area of the deepest ocean between the continental margin and the mid ocean ridge.

Oceanic ridge- continuous elevated zone on the floor of all the major ocean basins and verifying inn width from 500-50000 km’s.

Rift valley- along the axis of some segment of the oceanic ridge system is deep down faulted structures.

Seamount- an isolated volcanic peak that rises at least 1000 meters above the deep ocean floor.

Volcanic island arc- chain of volcanic islands generally located a few 100 km.’s from a trench where active subdution of one oceanic slab beneath another is occurring.

Ocean Exploration:

  1. Ocean exploration methods:

SONAR (echo-ranging) explain with detail

Scientist can use sonar to map the ocean floor. This is how the depth of the ocean is measured.Sonar, short for Sound Navigation and Ranging, is helpful for exploring and mapping the ocean because sound waves travel farther in the water than do radar and light waves

Seasat OR Geosat

Alvin OR Deep Flight

Alvin 1) traveled to the Mid-Atlantic Ridge and discovered fish that light up 2) explored near the Galapagos Islands and discovered giant white clams and huge tube worms d

Jason II AND Medea (together)

Jason I ) a robot used for exploration 2) can stay underwater longer (some up to a year)

What does scuba stand for? What is scuba equipment used for?

Self Contained Underwater Breathing Apparatus Humans use scuba equipment to explore the oceans.

2. Define submersible:

-underwater vehicles *submersibles can go deeper underwater than humans with scuba equipment.

3. How are satellites and sonar used?

Satellites and sonar are used to study ocean currents, salt content, temperature, wave heights, and ocean life. They can also map the ocean floor.

Ocean Water Chemistry

  • Earths oceans have a salinity of 35 parts per thousand
  • Salt water differs from freshwater by its lower freezing points, how well things float, and it has a higher density.
  • Ocean temperatures vary with the location and the season
  • As you descend through the ocean, the temperature decreases and the pressure increases