• Overall, the water resource available for vegetation restoration was 12±114 (mean ± SD) mm in the drylands (Fig2 a), approximately one-sixth of the national average in China. Water deficit areas accounted for 43.26% of the total drylands and had been recorded mainly in the western drylands, especially in the hyperarid areas (median value was -38.04mm). Water-surplus areas accounted for 56.74%, concentrated in the east and south (median value was 69.62mm). 
  • In terms of trends, 64.96% of the drylands showed a declining trend in additional water availability, which mainly occurring in the west. The whole region was also generally decreasing in the additional water resources, at a rate of 1.60 mm/year (Fig2 b and Fig2 c).