It is the branch of geology concerned with water occurring underground or on the surface of the earth. The very shallow flow of water in the subsurface is pertinent to the fields of soil science, agriculture and civil engineering, as well as to hydrogeology. It is the scientific study of the occurrence, distribution, and effects of groundwater. Hydrogeology is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth crust. The term geohydrology is often used interchangeably. Some make the minor distinction between a hydrologist or engineer applying themselves to geology, and a geologist applying them to hydrology. Geomorphology is defined as the scientific study of the origin and evolution of topographic and bathymetric elements made by physical or chemical processes operating at or near the earth surface. Geochemistry is the science that studies the mechanisms underlying the geological systems such as Earth crust and its oceans using the principles of chemistry.