Drought characteristics of the Lancang-Mekong basin and the role of reservoir regulation on streamflow

The Lancang-Mekong river basin has been experiencing droughts of increasing frequency and intensity, as a result of climate change. Investigating the drought characteristics and the impacts of reservoir regulation on the mainstream discharge of the Mekong river are both important for drought relief and transboundary water resources cooperation. Two meteorological drought indices (SPEI and SPI) were adopted to investigate the drought characteristics. A distributed hydrological model (THREW) was established for the whole basin (above Phnom Penh) to illustrate the natural runoff composition and impacts of reservoir regulation. The century-long time series database analysis shows that the basin is experiencing higher frequency of drought, and the proportion of drought occurring in the dry season is significantly higher than in the wet season. The 2019 drought is among the most severe droughts in the past century. The regulation of reservoirs in the basin could play an active role in dealing with droughts.