The Crescent Moon Spring, the top-ranked of Dunhuang's Eight Scenic Wonders, is situated in the deserts of Northwest China. How has it managed to avoid drying up for thousands of years, and what is the source of its water? Recently, the director of the Crescent Moon Spring scenic area responded to these questions from journalists.

So, what is the source of the spring's water?

The prevailing academic view is that the Crescent Moon Spring is fed by the Danghe River. Located to the west of the spring, the Danghe River has a riverbed that slopes from west to east, with an elevation higher than that of the spring itself. This topographical gradient allows groundwater from the Danghe River to flow eastward into the Crescent Moon Spring, providing a continuous water supply. Furthermore, the spring's bottom consists of a gravel layer. The large, loosely packed particles in this layer facilitate the easy recharge of the spring from the Danghe River's groundwater.

How has the Crescent Moon Spring managed to endure in the harsh desert for thousands of years without drying up?

The Danghe River originates from the glacial fields in the western Qilian Mountains, primarily fed by alpine snow and ice melt. For thousands of years, its waters have continuously flowed into the Dunhuang oasis, replenishing the Crescent Moon Spring. Therefore, as long as the Danghe River flows, the spring will not disappear. It is reassuring to note that historically, the river has never run dry, which is why the spring has also never vanished.

Is the Crescent Moon Spring at risk of disappearing? And what must be done to eliminate this threat?

As human settlement and activities expanded in Dunhuang, allowing its culture to flourish and reach the world, the water source of the Danghe River and the very existence of Crescent Moon Spring faced a crisis. In 1975, the Danghe Reservoir was constructed on the river, with its main canals supplying water for agricultural, industrial, and domestic use. However, the reservoir's operation cut off surface runoff to the lower reaches. The loss of this surface flow directly reduced groundwater recharge to the spring. Consequently, the spring's water area shrank significantly, with its average depth plunging from 7.5 meters to just 1.3 meters. In the years of lowest water levels, it even dropped to 0.8 meters—too shallow to maintain its crescent shape—bringing the spring to the brink of permanent disappearance.

To address this issue, an artificial water replenishment project was implemented for the Crescent Moon Spring. The process involves three key steps: First, water is pumped from the Danghe Reservoir to a regulating pond via the main canal. Next, this water is treated and then directed into seepage pools near the spring. Finally, it is channeled through artificial conduits to the bottom of the spring. This intervention successfully rescued the Crescent Moon Spring from the brink of drying up, providing a crucial reprieve from the threat of disappearance.

However, it remains uncertain whether this method can guarantee the permanent survival of the Crescent Moon Spring. Over the past decades, the Dunhuang region has undergone significant development. Population growth and economic expansion have led to a steadily increasing demand for water resources. Consequently, the amount of replenishment water available for the spring is inevitably diminishing. Ultimately, it is imperative to pursue more scientific planning and balanced development to prevent the loss of this natural wonder.