The extent of temporary water bodies increased in the drylands of northern China: a multiscale analysis based on MODIS data.

Understanding the dynamics of temporary water bodies (TWBs) is crucial for sustainable development in the drylands of northern China (DNC). Our objective was to quantify the dynamics of TWBs in the DNC between 2000 and 2015. First, we extracted TWBs in the DNC from 2000 to 2015 using the modified normalized difference water index based on Moderate Resolution Imaging Spectroradiometer data. Then, we examined the spatiotemporal patterns of TWBs in the DNC at multiple scales, ranging from the entire region to basins. We found that the area of TWBs increased significantly in the DNC (5.97 thousand km2 in 2000 to 9.92 thousand km2 in 2015) at an annual growth rate of 4.41%. The Heilongjiang Basin had the largest increase in TWBs (848 km2 in 2000 to 3230 km2 in 2015), with an annual growth rate of 23.41%. Such growth was mainly attributed to changes in precipitation in the DNC. We also found that approximately 1/3 of the increase in TWBs was distributed over grasslands and barren lands, which provide valuable water resources that may improve biodiversity and ecosystem services in the DNC. Thus, we suggest that effective measures are needed to manage TWBs to achieve sustainable development in the DNC.