Analysis of agricultural water resource vulnerability and its variable characteristics in Central Asia

Agricultural water utilization is a key link between natural environment and socio-economic system. It is important to investigate the vulnerability of agricultural water resources to secure water resource sustainability and mitigate flood and drought risks. To investigate the variable characteristics of agricultural water resource vulnerability in Central Asia, an index system was established with 18 indicators from three components—exposure, sensitivity, and adaptation—according to the scheme of vulnerability assessment. Based on the data on socio-economic factors, topography, land cover, and soil from 1992 to 2017, agricultural water resource vulnerability in Central Asia was calculated via the Equal-Weights and Principal Component Analysis (PCA) method. The results showed that the vulnerability of agricultural water resources in Central Asia was high in the south and low in the north. Among the five countries in Central Asia, the highest agricultural water resource vulnerability occurred in Turkmenistan, followed by Uzbekistan, Tajikistan, and Kyrgyzstan; the lowest agricultural water resource vulnerability occurred in Kazakhstan. These spatial patterns varied little over the past 26 years. Agricultural water resource vulnerability in Central Asia showed an increasing-decreasing-stabilizing pattern during the study period. Regional changes in the agricultural water resource vulnerability were dominated by a steady state during the entire study period. The variations in agricultural water resource vulnerability differed spatially over time, increasing in the west of Kyrgyzstan and Turkmenistan, declining in Uzbekistan, Tajikistan, and the Aral Sea region of Kazakhstan, and with little variation in the rest of the study area. Sensitivity analysis indicated that the agricultural water resource vulnerability varied in different areas of Central Asia. Temporal variations in the agricultural water resource vulnerability in the north were negatively related to the farmland irrigation quota and irrigation index but positively related to other indices. The sensitivities of indices were more complex in the south. Correlation analysis demonstrated that the forest coverage rate, proportion of agricultural water, farmland irrigation quota, water stress index, irrigation index, and agricultural water productivity ratio more strongly affected the spatial differences in agricultural water resource vulnerability than the other factors. Therefore, intensive agriculture practices, cropping structure adjustments, application of drought-tolerant crop varieties, and water-saving irrigation technology and measures should be implemented to reduce the vulnerability of agricultural water resources in Central Asia. This study analyzed the spatial and temporal variations in agricultural water resource vulnerability in Central Asia, explored the impact factors of these variations, and proposed recommendations to reduce the vulnerability of agricultural water resources. This work can inform agricultural water resources planning and management, adjustments of the agricultural production structure, and help to secure sustainable agricultural development in Central Asia.