Drought is a complex term which can have varied definitions including meteorological, agricultural and hydrological. There is no set time period for a drought declaration and it may be caused by decreased precipitation, decreased surface and/or subsurface water and/or increased evapotranspiration.
Many different indicators may be used to define drought, but from a meteorological viewpoint, the amount of precipitation is the main determining factor.
For the current Cai Be/Cai Lon sluice gate location in southern Vietnam, an ensemble of global climate models can provide some future guidance of precipitation change from present conditions, which can help inform future expectations of meteorological drought. Historically, the region experiences a dry season from December through April. This is the period most likely to experience meteorological drought.
Using the RSI CCHIP tool, ensemble average projections of future precipitation are provided using an ensemble of all AR5 assessment GCMs under the high emission scenario (RCP8.5). This is the current observed emission pathway. Near 40 GCMs are considered in the calculation of the averages shown in this document for a grid cell at the project location.