Geography Glossary - D
death rate
The number of deaths per 1000 individuals annually within a population
delta
The often triangular-shaped alluvial deposition area at the mouth of a river
demographic equation
The forumula that calculates population change. The increase (or decrease) in population is births minus deaths plus (or minus) net migration.
demographic transition
A model that explains the long-term changes of brith and death rates in a society
demography
The study of population statistics and trends, such as births, deaths, and disease
density
The number of items per unit area, such as persons per square kilometer
desert
An area with little precipitation or where evaporation exceeds precpitation, and thus includes sparse vegetation.
diffusion
The spread of ideas, disease, technology, etc. among places
doubling time
The amount of time for a given population to double, based on the annual growth rate. To determine doubling time, divide the growth rate as a percentage into 70. i.e., a growth rate of 3.5 represents a doubling time of 20 years