Hydrologists study water in all its forms: how water is distributed around the planet, where it occurs, the properties of water, its relationship with the environment, the water cycle, the chemical and biological processes involving water’s transit through the atmosphere, the polar ice caps.
Hydrologists might work in environmental protection, figuring out better ways to dispose of wastewater or of cleaning up polluted sites. They might also work in agriculture, studying how to improve the efficiency of irrigation systems for farms. Hydrologists interested in cities might work to find new sources of water and managing reservoirs, determine responses to flooding risks, design waste treatment systems, and assuring water quality.
Overall, being a hydrologist means working with lots of data, both out in the field collecting data, or in an office analyzing data.