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.
Watershed Analysis. A watershed is the area of land where all of the water that falls in it and drains off of it goes into the same place or common outlet. A watershed is also defined by topographic divides between two or more adjacent catchment basins, such as a ridge or a crest.