The study of water, including its properties, distribution, and transport. The Hydrologist is an expert on the physical and chemical properties of water and its interaction with other substances. He studies the distribution, flow, currents, and composition of underground and surface water. He is also knowledgeable about the processes of evaporation, precipitation, runoff, and glaciation. He can work with Civil Engineers to address issues with water supply, erosion, irrigation, snow pack, and flood control. In the future related skills can specialize in the other types of liquids commonly found on planetary bodies, such as liquid methane.