Characteristics of Change in Annual Runoff Volume of Karez in the Turpan Basin in Recent 30 Years

Karez is an important water conservancy facility in the Turpan Basin.The purpose of this paper is to alleviate the decreasing status of karez , analysing the changing characteristics of annual runoff volume of karez in recent 30 years, which is of great significance for agricultural irrigation, cultural heritage preservation, tourism development and so on. Based on the discontinuous 13 years of annual runoff volume of karez in the study area for the period 1990—2022, as well as year-by-year the exploitation amount of electro-mechanical wells, and water supply from surface water sources, statistical analyses were performed using SPSS 20 software to interpolate missing measurements, and use the trend and mutation analyses to determine their change curves and mutation years. The results of the study indicate: between 1949 and 2023 the number of karez reduced from 1084 to 169,implying that an average of 16 karezs dried up or disappeared each year, while the flow rate declined from 16.11 m3/s to 3.6 m3/s. The correlation coefficients between the annual runoff volume of karez and the exploitation amount of electro-mechanical wells, the amount of water supplied by surface water sources, the irrigated area and precipitation were -0.890, -0.149, -0.660, and 0.764. Through the construction of a model of the relationship between the annual runoff volume of karez and the exploitation amount of electro-mechanical wells and the amount of water supply from surface water sources, and the average relative error between the measured value and the predicted value was 1.8%, which effectively solved the problem of missing data. In addition, the exploitation amount of electro-mechanical wells and the amount of water supplied by surface water sources as a whole showed a fluctuating upward trend, and the annual runoff volume of the karez increased and changed abruptly in 2006, the reasons for the sudden change might be related to the government's implementation of regulations for the protection of karez. Therefore,in view of the important cultural and engineering value of karez , make greater efforts in the future to protect it and promote the sustainable use of water resources and high-quality development in the Turpan Basin.