Background Sloping cropland is subject to most serious soil erosion in the Loess Plateau. Although the conversion of cropland to forests or grassland has been implemented for nearly 20 years, cropland on steep slope still exists in the hilly Loess Plateau which is in need of detailed survey and effective management.

Methods Chabagou and Qingshuigou in Zizhou county, Shaanxi province which are also in the flooding area of "7·26" torrential rainstorm were selected as typical watershed of the type Ⅰ area of the hilly and gully region of the Loess Plateau to compare distribution of sloping cropland between watersheds with and without comprehensive management. Based on high-resolution satellite remote sensing and UAV images, GIS technology was used to extract and analyze sloping cropland area and its distribution. Topographic map with a scale of 1:10 000 and Digital Surface Models (DSM) were used to extract and analyze topographic parameters such as slope gradient, slope length, slope position and upslope catchment area.

Results 1) In 2017, the area of sloping cropland accounted for 11.08% of the total area of Chabagou watershed. Sloping cropland area in Shejiagou, a branch watershed of Chabagou with comprehensive management, accounted for 6.90%, and that in Qingshuigou watershed, with serious soil erosion causing the dam break during "7·26" rainstorm, accounted for 11.15%. 2) The average gradient of the sloping cropland in Qingshuigou was 32.54°, of which the ratio >25° accounted for 94.01%. The average gradient of the sloping cropland in Shejiagou was 20.62°, of which the ratio > 25° accounted for 36.47% and the ratio > 15° accounted for 79.62%. The average slope length of sloping cropland in Qingshuigou and Shejiagou was 38.50 m and 32.58 m respectively, of which 94.06% and 86.12% was over 20 m. More than 70% of sloping cropland in Qingshuigou and less than 50% in Shejiagou belonged to the long-steep sloping cropland. 3) More than 99% of the sloping cropland of Shejiagou and Qingshuigou catchment areas were located in the middle slope position and only a few were located in the upper slope position. Compared with in Qingshuigou, the ratio of upslope catchment area to sloping cropland area in Shejiagou was larger.

Conculsions There is still a certain proportion of steep sloping cropland in the type Ⅰ area of the hilly and gully region of the Loess Plateau which is an important source of runoff and sediment. The lack of attention to the statistics of steep sloping cropland has greatly increased the risk of severe soil erosion and flood disasters under extreme precipitation conditions.