Group 2 (Hydrologic cycle & Water Balance)

Hydrology

Is the scientific study of the movement, distribution, and management of water on Earth and other planets.

Branches of Hydrology

• surface water

• ground water

• chemical hydrology

hydrologic cyle

Commonly known as the water cycle, the hydrologic cycle is

the continuous movement of water between the Earth's

surface (land and oceans) and the atmosphere

major processes

• evaporation or transpiration

• condensation

• precipitation

• infiltration & runoff

evaporation

is a natural process in the water cycle where liquid water changes into

water vapor due to the heat energy provided by the sun.

transpiration

is the release of water vapor from plants into the atmosphere through small openings in their leaves called stomata.

condensation

happens when water vapor cools down and changes back into liquid water.

precipitation

occurs when condensed water droplets in clouds become heavy and fall to Earth.

runoff

is water that flows over the land surface toward rivers, lakes, or oceans.

Infiltration

is the process by which water on the ground surface enters the soil.

Percolation

is the downward movement of infiltrated water through soil and rock layers.

Groundwater flow

is the movement of water within underground aquifers.

storage

refers to water held in different parts of the hydrologic cycle for varying lengths of time.

Freshwater Distribution

It is the primary mechanism for moving water from the salty oceans to dry land, providing the freshwater needed for life.

Climate Regulation

The movement of water vapor helps distribute heat around the globe, regulating Earth's temperature.

Nutrient Cycling

As water moves, it carries essential minerals and

nutrients through ecosystems.

Natural Filtration

Processes like infiltration through soil and evaporation act as natural filters, purifying water.

water balance equation

P=ET+Q+ΔS

Atmosphere Surface Water

Evaporation transfers water from surface water bodies like lakes

and oceans to the atmosphere, while precipitation returns it as rain or snow.

Surface Subsurface Water

Surface water infiltrates into subsurface soil and aquifers as recharge, or groundwater discharges into streams and wetlands. In braided rivers, hyporheic exchange allows surface water to flow into gravel beds and return, mixing with groundwater.

Subsurface Atmosphere

Subsurface water reaches the atmosphere via evapotranspiration, where plants transpire soil moisture or groundwater. Feedback mechanisms include: drier soils from high transpiration reducing further evaporation, creating negative loops that limit moisture loss; and increased vegetation drawing more water to sustain transpiration, which acts as a positive feedback that maintains the cycle.

cycles connections

These interactions form the hydrologic cycle's core: precipitation from atmospheric vapor replenishes surface water, infiltration feeds subsurface storage, and evaporation/transpiration recycles water upward.

examples of hydrology in real-life

• Civil engineering & Flood control

• Agriculture & irrigation

• Environmental Protection

• Public Health