INTRO TO HYDROLOGY - QUIZ 1

jan 12, 2026 QUIZ 1

Hydrology

is the scientific study of the movement, distribution, and management of water on Earth including the water cycle, water resources, and drainage basin sustainability.

FORMAL DEFINITION OF HYDROLOGY

the science that deals with the occurrence, circulation, distribution, and properties of the waters of the Earth and its atmosphere, including their interaction with the physical and biological environment throughout the hydrologic cycle.

Precipitation, Evaporation, Infiltration, & Runoff

What’s the Hydrologic Cycle?

Precipitation

water released from clouds that falls to the Earth’s surface in the form of rain, snow, sleet, or hail. It is the primary source of freshwater on land.

Evaporation

the process by which liquid water from oceans, rivers, lakes, and soil surfaces changes into water vapor due to heat from the sun and rises into the atmosphere.

Infiltration

the process by which water on the ground surface enters the soil and moves downward to recharge groundwater.

Runoff

the portion of precipitation that flows over the land surface into streams, rivers, lakes, and oceans when the soil is saturated or impermeable.

What’s the role of Hydrology in Understanding water movement?

The scientific study of water movement—including rainfall, runoff, and groundwater—to help manage resources and predict natural disasters.

Occurrence of water

The different forms and places in which water exists on, above, and below the Earth’s surface.

Atmospheric water, Surface water, Groundwater, Soil moisture, Frozen water, Biological water

What are the Occurences of water

Water vapor, Clouds, Precipitation

Give an example of Atmospheric water

Rivers and streams, Lakes and ponds, Reservoirs, Wetlands, Oceans and seas

Give an example of Surface water

Wells, Tube wells, Springs

Give an example of Ground water

Agriculture, Crop production, Plant survival

What is Soil Moisture important for?

Glaciers, Ice caps, Snow, Permafrost

Give an example of Frozen water

Water contained in plants, animals, and humans

Give an example of Biological water

Distribution of water

How water is spread or shared among different parts of the Earth.

3%

What percent is Fresh Water?

97%

What percent is Salt water?

MOVEMENT OF WATER

How water travels from one place to another on Earth

Flood forecasting

predicting when a flood may occur, how big it will be, and which areas may be affected.

Urban Drainage System

a system that collects and removes rainwater from cities and towns.

Surface waters

include streams, rivers, lakes, reservoirs, and wetlands. These water bodies hold water on land from rain and snow.

Stream

is used to represent all flowing surface water, from brooks to large rivers.

Rivers

Large flowing bodies carrying water across landscapes to

oceans or lakes.

Lakes

Standing freshwater bodies formed by natural depressions or

barriers.

Reservoirs

Man-made lakes created by damming rivers for storage.

Streams

Smaller flowing channels that feed into larger rivers.

Runoff

flow from a drainage basin or watershed that appears in surface streams.

watershed, or drainage basin

is the land area where rain and snow drain into one river and its branches. It can be small or huge, like the Mississippi watershed covering 40% of the U.S. and flowing to the Gulf of Mexico, or the Amazon draining much of South America.

Streamflow

the amount of water (volume per time) flowing past a point in a river or stream, including any dirt or solids mixed in.

Groundwater

is the water found underground in saturated zones, filling the cracks and spaces in soil, sand, and rock beneath the land surface.

Water table

the upper surface of the underground zone where soil and rock are completely saturated with water (the zone of saturation), separating it from the unsaturated zone above.

Aquifer

is an underground layer of water- bearing material consisting of permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt).

Recharge

the process where water enters the ground and replenishes groundwater.

Discharge

the outflow of water from the aquifer, occurring naturally through springs, wetlands, rivers, lakes, or oceans, and unnaturally via wells, sustaining surface water and ecosystems.