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Hydrology and the Hydrological Cycle

HYDROLOGY
The science of hydrology deals with the occurrence and distribution of waters of Earth, including their chemical, biological and physical properties, and their interaction with the physical environment. Hydrological data and information are used as the basis for solving practical problems of floods and droughts, erosion and sediment transport, and water pollution. Hydrology plays a central role in many environmental initiatives that address concerns on the increasing pollution of surface and ground waters, acid rain, drainage of wetlands and various other type of land-use change, together with the impending threats to fresh water resources posed by climate change and sea-level rise.

The Water Vapor
The water cycle is the process by which water moves around, through, and above the Earth, continually changing from liquid water to water vapor and ice. The evolution of water through the cycle involves a number of phase changes and interactions that depend primarily on the absorption of solar energy.

Sunshine
Solar radiation falls on water in rivers, lakes, streams, wetlands and oceans and makes the water warmer. This converts the water into vapor or steam. The water vapor then moves into the air, increasing the moisture content of the lower atmosphere.

Evaporation
The conversion of liquid water to vapor is called evaporation. The water vapor or steam leaves the stream, river, lake or ocean and ascends into the air, where it gradually expands, cools and condenses to form clouds. Evaporation occurs from open water surfaces, the top layer of soils and through the leaves of plants and vegetation. This latter process is known as transpiration. The combination of evaporation and transpiration from vegetation surfaces is referred to as evapo-transpiration.

Rain
When the temperature is warm, the concentration of water droplets in clouds increase, and the clouds grow vertical extent and girth. As the cloud droplets cool and increase in size, rain starts to fall. The rains fall onto the land and runs into streams and rivers. The water in the streams and rivers runs into lakes and finally into the ocean. Some of the rain that falls soaks into the ground and stays there until plants absorb it or until it goes deep enough into the ground that it is called “groundwater” and goes to people’s wells.

Snow
Snow is similar to rain except it falls when the air is cold, like during late fall and winter in maid and high latitude regions of both hemisphere. Snow usually stays on top of the ground until it melts, then it turns into water and runs into streams and rivers. Some of the water from melted snow also goes into the ground and become groundwater. Generally ground water moves very, very slowly towards the ocean and may take hundreds of years to reach the ocean.

Check this page for future information on Hydrology and Hydrological monitoring in Belize, or write to: ozone@btl.net

Hydrological Stations of Belize

Watersheds of Belize

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