Background Pisha sandstone area is one of the most serious soil erosion areas in the Loess Plateau. The government has given great attention to the ecological recovery of Pisha sandstone area and has implied a lot of researches in this area. However, the treatment effect is not very satisfactory at present. One reason lies in the lack of detailed classification of geomorphological types in the study area. Geomorphological characteristics have important influence and restriction on soil erosion and other surface processes as well as ecological restoration. The fine classification of geomorphological types can make the ecological construction of soil and water conservation zoning, according to local conditions, has important practical significance. This work is to clarify the eroded geomorphological characteristics of Pisha sandstone area and provide precise measures for soil erosion control.

Methods Based on the DEM data of 30 m resolution in the research area, the best statistical window of relief degree was determined by mean change-point analysis, and the optimal topographic factors were determined by combination of correlation coefficient and principal component analysis. On this basis, the geomorphological characteristics and spatial distribution of the study area were analyzed.

Results 1) The best statistical window of relief degree in Pisha sandstone area under this scale data source is 16×16 (0.230 4 km²). 2) The best combination of topographical factors in this area are surface cutting depth, profile curvature, slope, elevation and variation of slope aspect, and the cumulative contribution rate is more than 70%. 3) The surface cutting in the Pisha sandstone area is in the middle level, mainly in the eastern part of the study area. The overall altitude is higher and 94.53% of the area is in the middle altitude. The slope is chiefly gentle slope and ramp, and the two total areas account for 99% of Pisha sandstone area. The gentle slope is distributed in the western part of the study area, the ramp is distributed in the east, and the variation of slope aspect is mostly between 15°-75°. 4) The main landform types include tableland and hill, which are distributed in the whole Pisha sandstone area, with an area ratio of 88.92%.

Conclusions The results reveal the geomorphological characteristics and spatial distribution of the Pisha sandstone area, which is of practical significance to the ecological construction of soil and water conservation in this area. It helps to efficiently control the erosion area and provides reference for other erosion areas.