IMD declares an end to droughts in India
Jan 23, 2016
Since it can’t control the weather but can control language, the state forecaster India Meteorological Department (IMD) has decided to simply replace the word “drought” to describe poor rainfall with “deficient year” and “large deficient year”.
In a circular issued, IMD also changed several terms used by the forecaster based on the recommendation of a committee that was set up by the director general.
While drought is definitely an easier term to understand than “deficient year” and “large deficient year”, the latter two better express nuances and differences. After all, there are droughts and droughts.
The decision to tweak the terminology comes at a time when India is facing the fallout of its worst monsoon in six years, with a 14% rain deficit. A total of 302 districts across India—nearly half the total number in the country—received at least 20% less rainfall than normal in 2015, according to IMD.
According to IMD’s earlier classification, “when the rainfall deficiency is more than 10% and when 20-40% area of the country is under drought conditions, then the year is termed as an All India Drought Year”
Drought is not a simplistic subject. IMD can define a meteorological drought, but agricultural and hydrological droughts are different. The first refers to a poor agricultural season and the second, low rains.
Meteorological Drought:d It is defined usually on the basis of the degree of dryness (in comparison to some “normal” or average amount) and the duration of the dry period.
Agricultural drought links various characteristics of meteorological (or hydrological) drought to agricultural impacts, focusing on precipitation shortages, differences between actual and potential evapotranspiration, soil water deficits, reduced groundwater or reservoir levels, and so forth.
Hydrological drought is associated with the effects of periods of precipitation (including snowfall) shortfalls on surface or subsurface water supply (i.e., streamflow, reservoir and lake levels, groundwater). The frequency and severity of hydrological drought is often defined on a watershed or river basin scale. Although all droughts originate with a deficiency of precipitation, hydrologists are more concerned with how this deficiency plays out through the hydrologic system.
source: livemint, unl.edu