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.
The term watershed is used to describe a smaller area of land that drains to a stream, lake or wetland. Many watersheds can reside within a large river basin. basin is characterized by a flow of streams and creeks. The duty of a river basin is to send all the water in the form of streams and creeks falling on the land into a principal river and in turn into the ocean.