Abstract: In order to understand the spatial distribution characteristics of surface water resources in Ningxia and provide reference for the rational utilization of water resources in the region, based on the Joint Research Centre ( JRC ) global surface water data set, statistical analysis, Mann-Kendall method, wavelet analysis and other methods were used to study the variation characteristics, mutation characteristics and oscillation period of surface water in Ningxia from 1990 to 2019, and the spatial evolution characteristics of water density in the region from 1990 to 2020 were also analyzed. The results showed that the surface water area in Ningxia increased by 141.28 km² from 1990 to 2019, with an increase of 188.3%, and the number of water bodies increased by 1 861, with an increase of 42.0%. The total area and number of water bodies showed a decreasing trend from 1990 to 1999, the area of water bodies increased significantly after 2006, the number of water bodies increased significantly after 2016, and the number of water bodies increased abruptly in 2014. The total area and total number of water bodies mainly had the first oscillation main period of 22 years and the second oscillation main period of 30 years. From the perspective of spatial density of water bodies, the fastest growing area of water bodies in Ningxia was along the Yellow River, the largest area of density increase was the Yinbei Plain Irrigation District, and the density of water bodies in the central and southern regions had expanded in space.

Key words: surface water, spatial density, temporal-spatial evolution, variation period, mutation test, Ningxia Hui Autonomous Region