Researchers protect lake in NW China from shifting sands

LANZHOU -- Chinese researchers have developed strategies to protect the Yueya Spring from shifting sands, according to the Northwest Institute of Eco-Environment and Resources under the Chinese Academy of Sciences.

The Yueya Spring, a crescent-shaped lake surrounded by giant sand dunes, is located at the Mingsha Mountain, or Singing Sand Mountain, in Dunhuang city, Northwest China's Gansu province. According to ancient historical documents, the dunes and the lake have coexisted for at least two millennia. The sand has never moved into the spring, and the water has always kept a sweet and crystal clear texture, which has made it a world-renowned scenic spot.

Over past decades, the wind-blown sand movement has posed a threat to this precious lake, as the dunes to the north and south tend to migrate toward each other, resulting in a shrinking lake area. These threats posed by wind-blown sand, which could potentially lead to the disappearance of the lake, have attracted widespread attention.

Then a research team from NIEER started to protect the lake from shifting sands via research with the support of the Administrative Office of the Dunhuang Singsing Sand Mountain and Crescent Spring National Scenic Spot.

They set up about 10 monitoring spots to intensively monitor and observe the dynamic changes of pyramid-shaped sand dunes and wind-sand movement around the lake. Through their work, they discovered the root causes of the lake's shrinkage and implemented various specific mitigation measures.

With the aid of scientific techniques, such as three-dimensional laser scanning for detection, high-precision wind tunnel test, numerical simulation based on real terrain, the research team has managed to successfully comprehended the sand-spring-coexistence mechanism. Subsequently, they were able to identify the scientific causes of the threat posed by wind-blown sand.

"Our long-term monitoring shows that the increased tall vegetation and buildings in the upwind direction and around the lake have changed the balance of the original multi-wind sand flow field, resulting in an imbalance in the shape of the sand mountain," said Liu Benli, a researcher with NIEER.

Li Haijiang with the Administrative Office of the Dunhuang Singsing Sand Mountain and Crescent Spring National Scenic Spot said that they implemented measures such as controlling the scope and height of upwind urban construction, removing new buildings and trees inside and outside the scenic area, and carrying out ventilation renovation on buildings in the core area. This has recovered the strength of the wind blowing across the lake, gradually restored the shape of the sand mountain, and allowed the scope of the lake water to be more stable.

"These measures effectively mitigated the threat posed by the blown-sand problems to the lake," said Liu, adding that compared to most sand control works that aim to reduce wind speed and fix surface sand by implementing biological and engineering measures, the mitigation of the blown sand risk for the lake focuses on the restoration of natural wind flow and the elimination of increased wind obstacles, which makes the protection work unique and attractive.

The study results related to protection have been published online in the journal "Research in Cold and Arid Regions" recently.