Hydrology
Definition of hydrology
Hydrology is a field of study focused on the Earth’s waters, their occurrence, circulation, and distribution, as well as the chemical and physical properties of water. It also examines the interactions between water and the physical and biological environment, including the impacts of human activities on water systems. (Tieteen termipankki)
Why is it important to study water?
Although a large portion of the Earth is covered by water, there is still a shortage of usable water. This is because 97% of the planet’s water is salty seawater, which is not drinkable without treatment. The remaining 3% is freshwater, with dissolved substances at concentrations below 0.5‰. Thus, freshwater—used to supply clean water for households, industries, and agriculture—is an extremely valuable resource.
Freshwater resources are found in underground aquifers, glaciers, rivers, and lakes. These resources renew naturally through the water cycle. However, it is essential to avoid overexploitation, as this can prevent their natural renewal. Research plays a key role in improving the sustainability and availability of water resources.
Freshwater storages
Freshwater suitable for drinking can be found in surface waters such as lakes and rivers, as well as in groundwater. However, the majority of the Earth’s freshwater is stored in glaciers. The usable portion of freshwater is less than one percent of all the water on Earth. (WWF.fi)
Natural cycle of water
Water is a renewable natural resource that undergoes an eternal cycle on Earth. It evaporates from the Earth’s surface into the atmosphere and returns as precipitation. Water is purified as it passes through the atmosphere because evaporation transfers only water molecules. Once it falls to the ground, rainwater moves as runoff into surface and groundwater systems and eventually into the oceans, evaporating along the way or from the ocean back into the atmosphere. The total amount of water on Earth remains constant throughout the water cycle. (Leppäranta et al., 2017)
Water supply and drinking water quality
Water utilities process freshwater (raw water) into drinking water, also known as tap water. Drinking water quality is subject to strict standards, and in Finland, tap water is exceptionally clean.
The quality of water varies by region, depending on factors such as the source of raw water and the condition of the distribution pipes. Surface water sources, like lakes and rivers, often require more extensive treatment, while groundwater may need minimal processing due to its natural filtration. Regular maintenance of water infrastructure ensures the safety and reliability of the water supply.