Death due to disease is called death by natural causes. There are four main types of disease: pathogenic disease, deficiency disease, hereditary disease, and physiological disease. Diseases can also be classified as communicable and non-communicable disease.
A watershed is the area of land where all of the water that falls in it and drains off of it goes to a common outlet.
A watershed is an area of land from which all water drains, running downhill, to a shared destination-a river, pond, stream, lake, or estuary. A watershed is a catchment basin that is bound by topographic features, such as ridge tops. A watershed has three primary functions.