Observation of mega-dune evaporation after various rain events in the hinterland of Badain Jaran Desert, China

The formation mechanisms of the mega-dunes and lakes in the hinterland of Badain Jaran Desert, China, is the focus of extensive academic research in the field of geoscience, and an often debated topic is whether atmospheric precipitation on the mega-dune can infiltrate to recharge groundwater. In the present study, the probability distribution functions and the return period analysis of extreme daily precipitation based on long-term precipitation records for the southern margin of Badain Jaran Desert and 2-year observation of hinterland precipitation were used to classify precipitation in the desert region. The data of automatic weather station and eddy covariance system in the desert hinterland were used to analyze evaporation on the mega-dune surface after various rain events. The results showed that the rain events in the desert could be divided into three categories. The first is conventional precipitation (CP), which is below 5 mm, accounting for roughly 90 % of all rain events in the desert. The second and third categories are ordinary annual maximum (OAM) and extreme precipitation (EP), in which precipitation is roughly 20 mm and more than 40 mm, respectively. The atmospheric precipitation of CP and OAM evaporated from the mega-dune surface in 1-3 days and 3-4 weeks, respectively. Following an EP event, the mega-dune evaporation was negatively influenced by the upper dry sand layer, and a lengthy period was required for its complete removal. The accumulative evaporation and accumulative precipitation of all three types of rain events indicated that local atmospheric precipitation had no significant contribution to recharging the groundwater system in the hinterland of Badain Jaran Desert. This research will benefit comprehensive elucidation of the formation mechanism of lakes in the hinterland of Badain Jaran Desert.