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The purpose of this paper is to examine the status of the supply reliability of groundwater irrigation, and discuss how it is affected by climate change and tubewell density in rural China.

This study is based on a nine-province village survey and secondary climate data. A Tobit model (or censored regression model) was used to estimate the determinants of supply reliability of groundwater irrigation.

Results show that the supply reliability of groundwater irrigation was 89 percent on average in the past three years. The non-linear relationship in the econometric results revealed that the 30-year annual temperature significantly influenced the supply reliability of groundwater irrigation. When the temperature rises above the turning point (6.30°C), it shifts from a positive to a negative relationship with the supply reliability of groundwater irrigation. The 30-year annual temperature in eight of the nine provinces (i.e. except for Jilin Province) was higher than the turning point. If the temperature increases by 20°C in the future, other factors being constant, the supply reliability of groundwater irrigation will decline by 20 percent. However, if precipitation increases by 10 percent, the supply reliability of groundwater irrigation could improve by 3 percent, while reducing precipitation by 10 percent will lower the supply reliability of groundwater irrigation by 3 percent. Increasing the density of tubewells considerably improves the supply reliability of groundwater irrigation. However, although increasing the density of tubewells may yield enough groundwater for irrigation, this one-sided approach raises sustainability concerns.

Although increasing the density of tubewells may ensure that enough groundwater is available for irrigation, such a conclusion is one sided, and sustainability concerns should be raised in assessing this method of creating supply reliability.

This paper improves the understanding of the impact of climate variables on agriculture irrigation and water supply reliability in the micro scale, and provides a scientific basis for relevant policy making.