Siertan Lake

　　Yanchi County in Ningxia is situated on the edge of the Mu Us Desert, where the climate is dry and rainfall is scarce. The poetic line “lonely smoke in the desert rises straight” aptly depicts the natural scenery of this area.

　　However, after five consecutive years of drought, since the spring of 1996, within a very short period, a miracle occurred in the southeastern part of Yanchi County—between the suburban villages of Siertan, Beitan, and Dongguozhuang, and the villages of Liuyaotou, Taipingmiao, and Zhaojitang in Qingshan Township. Due to a rise in the groundwater level, a lake formed, stretching approximately 10.5 kilometers from east to west, covering a total area of over 30,000 mu, with the deepest point reaching 5.7 meters and an average depth of about 1 meter.

　　In Dongguozhuang Village of the suburban township, there are 28 households who have longed for water for generations. The entire village relied on wells that were only 5 meters deep for drinking water. Every spring, the water supply was insufficient, forcing villagers to transport water by cart or carry it on their backs from more than ten li away. Wang Shengyuan, a man over 60 years old, said: After the Spring Festival in 1996, the water in the wells rose, and the water turned from salty to sweet. By the end of February, water began flowing out of the wells. Out of the village’s 27 wells, nearly a third started to overflow. Even the previously very dry threshing grounds began to sink underfoot, walls in houses that had stood for over eight years started seeping water outward, and the kang beds became very damp... Many elders, who had lived for most of their lives, had never seen anything like this. How did such a mythical large lake form? Local residents discussed it widely. In response, experts from Ningxia conducted on-site investigations and monitoring, first concluding that the formation of the lake had no direct connection to crustal movements and was not a precursor to an earthquake anomaly. Finally, they offered the following explanation:

　　…No signs of deep water upwelling were found during the investigation. Near Siertan, water was observed seeping from the water-rich Cretaceous sandstone strata, indicating that the accumulated water in the salt marsh area resulted from descending water. Remote sensing data analysis revealed that in the area around Yanchi County and nearby, there is an ancient river channel extending from north to south. This ancient riverbed lies in a low-lying area, making it an ideal water storage site. The newly formed lake is located precisely on this ancient river channel. Since autumn 1996, this area has experienced concentrated rainfall, richer than in previous years, which gradually increased the moisture content in the Cretaceous sandstone of the ancient river channel, bringing it close to saturation. Coupled with the cold spring of 1997, compared to previous years, the spring flood season arrived later but more intensely, causing a large outflow of water from the rocks. This water converged in the low-lying areas, raising the level of underground water and resulting in pooled water in some sections.