Underground Great Wall Secures Water for Arid Turpan

The Turpan karez, a remarkable and ancient irrigation system that dates back 2,000 years, plays a critical role in collecting snowmelt underground, which is essential for sustaining local agriculture in the arid environment of Turpan. This extraordinary network of underground channels, often referred to as the Underground Great Wall, has been recognized as a vital part of cultural heritage and is listed as a UNESCO World Heritage site.

The Great Wall of China famously spans across the northern regions, but in northwestern Xinjiang, the karez presents a hidden engineering marvel that is equally significant. The underground system provides an ingenious solution to the challenges posed by the region's extreme climate, characterized by an annual evaporation rate of 3,000 millimeters, compared to a mere 16 millimeters of annual precipitation.

In Turpan, where the scorching heat dominates the climate, the urgency of collecting rainwater, minimizing evaporation, and delivering water to crops and households has historically posed major challenges. Approximately 2,000 years ago, ancient engineers addressed this concern by creating a sophisticated underground irrigation system called karez.

This innovative network harnessed the natural sloping terrain from the Tianshan Mountains down to the Turpan Basin. The engineers devised the system to collect melted snow and transport it through underground channels, thereby significantly reducing water loss due to evaporation and ground absorption.

The karez system is vast, stretching over a remarkable 5,000 kilometers, equivalent to distance traveled between Beijing and Urumqi. Today, about 238 of these channels remain operational, continuing to support agriculture in a highly challenging environment.

The recognition of the Karez System Cultural Landscape as a UNESCO World Heritage Site in 2014 further underscores the importance of this ancient feat of engineering. It reflects not only the historical significance of the system but also the profound ingenuity of the local people who developed it to thrive in an inhospitable landscape.

By connecting the mountainous regions with the dry basin, the karez serves as a critical resource, enabling the vibrant agriculture that characterizes Turpan today. As climate conditions continue to evolve, preserving and understanding the karez system becomes increasingly vital for both cultural heritage and sustainable water management.