Applied Hydrology

Applied Hydrology Applied hydrology examines the applications of hydrology, and hydrology is the science in which the origin, properties, and form of the movement and circulation of water in nature are studied. Water is a substance that in its liquid state is the chemical compound H2O, which is always found in nature accompanied by some amount of insoluble, soluble, and gaseous substances. Natural water, the greatest part of which consists of the aforementioned chemical compound, is found in abundance on the Earth, such that out of 510 million square kilometers of the Earth's surface, 361 million square kilometers are made up of seas. The oceans of the Earth's surface contain 97.5% of all the Earth's water, and the remaining 2.5% constitutes fresh water, which is found on the Earth in the following various forms: 69% of all fresh water: polar ice. 30% of all fresh water: fresh groundwater. 0.3% of all fresh water: surface water, including rivers and fresh lakes. 0.7% of all fresh water: water present as moisture in the ground or in the form of swamps on the Earth's surface. Water in nature follows a closed cycle, during which it changes its state from liquid to vapor or to solid (ice). Part of the water on the Earth's surface evaporates due to the energy from solar radiation and forms clouds as very fine particles (about 0.02 mm in diameter). Under normal conditions, these particles have a very low fall velocity due to wind currents and are almost suspended in the air. These relatively large droplets fall toward the Earth under their own weight. If raindrops encounter a cold layer of air along their path, they turn into snow or hail. Sometimes the aforementioned saturation state may occur entirely at the Earth's surface, in which case dew is formed.