The Effects of Oasis on Aeolian Deposition under Different Weather Conditions

In arid regions, wide sandy and Gobi deserts are interspersed with oases of different sizes and shapes. Due to typically located within or immediately adjacent to dust source regions, oases often experience frequent dust events and receive a high rate of aeolian deposition. High aeolian deposition rates (ADRs) in the oases can be able to not only harm the local ecological environment and human health, but also promote the occurrence and development of desertification and thus threaten the existence of oases. Therefore, it is of great significance to examine fluxes and patterns of aeolian deposition in oases especially under different weather conditions.

The Qira oasis, located in the downward area of the atmospheric circulation of the Taklimakan Desert, can provide lager amounts of sand-dust materials to Qira via dust events. So, aeolian deposition samples during dust storms and non-dust storms were collected respectively inside and outside the Qira oasis to examine the spatial variation patterns of aeolian deposition and to reveal the oasis’ effects on aeolian deposition under different weather conditions.

The results showed that the monthly ADRs varied greatly with seasons and sites, ranging from 19.4 to 421.2 g/m²/month and averaging 198.8 g/m²/month. Aeolian deposition in the oasis was composed dominantly of sand and silt.

Based on the variations of ADRs from the four sites, it can be found that the oasis exhibits two different effects on aeolian deposition under different weather conditions. During dust storms, the oasis demonstrates a significantly shielding effect due to the obstruction of the oasis-protection systems, resulting in most aeolian particles being deposited at the windward side of the oasis. While during non-dust storm periods with weak winds, the oasis exhibits an ‘‘attracting’’ effect on aeolian deposition, leading to a higher ADR inside the oasis.

Owing to the annual ADR is dominated by the non-dust storm ADR in Qira, the oasis seems to become an important aeolian deposition area caused by the ‘‘attracting’’ effect of the oasis. The result was published in Environmental Earth Sciences in 2013, 68: 103-114.