What is drought?
Drought can be divided into four different categories—meteorological,
agricultural, hydrological and
socio-economic. There is no universal definition of
drought, but a working definition of meteorological
drought is that it is ‘‘an extended period—a season, a
year, or several years—of deficient rainfall relative to
the statistical multi-year mean for a region’’ (Druyan,
1996b). Drought must be distinguished from aridity,
in that regarding the above definition for drought,
aridity occurs in a region where there is a high
probability of rainfall below a low threshold (e.g.
20 cm per year; Druyan, 1996a) for a long and
possibly indeterminate time (Coughlan, 1985).