It is often presumed that drought is simply a lack of rainfall, however the study challenges this assumption: “Assuming that total annual rainfall and drought are highly associated, meaning that the less the rainfall in a given year, the more the drought impacts, then, data does not really allow establishing this relationship except the extreme meteorological drought as in 2004 in some provinces. For example, Kampong Speu province experienced the most severe damage on paddy production in 2004 at 38,257 hectares (ha) of area cultivated and received total rainfall at 921 millimeters (mm). However, the least rainfall was not in 2004 but in 1997 at 770 mm and damaged on cultivated area at 14,962 ha.”
As a result, it is clear that the amount of annual rainfall (or lack of) does not necessarily equate to a drought.
Indicators need to be developed which consider this discrepancy, as well as the country context and four types of drought acknowledged in current literature (meteorological, agricultural, hydrological and socio-economic).
Each type of drought is measured using different approaches, making it challenging to find a universal definition and measure. For example, meteorological drought is considered to be a ‘precipitation deficit’ that can be measured using the Standardized Precipitation Index (SPI), whereas a hydrological drought refers to a lack of water sources (including surface water, ground water, streams etc.) and is commonly measured using a Normalized Difference Water Index (NDWI).