Acta Geographica Sinica ›› 2013, Vol. 68 ›› Issue (7): 921-932.

### Spatial variation of hypsometric integral in the Loess Plateau based on DEM

ZHU Shijie, TANG Guo'an, LI Fayuan, XIONG Liyang

1. Key Laboratory of Virtual Geographic Environment, Ministry of Education, Nanjing Normal University, Nanjing 210023, China
• Received:2013-03-12 Revised:2013-05-02 Online:2013-07-27 Published:2013-07-27
• Supported by:
National Natural Science Foundation of China, No.40930531; No.41171320; Open Foundation of State Key Laboratory of Resources and Environmental Information System, No.2010KF0002SA

Abstract: Hypsometric integral is a terrain analysis factor with apparent physical and geomorphologic meanings which could reflect the landform erosion stage and evolution process. As a macroscopic parameter and method in terrain analysis, the applications of hypsometric integral could reveal the quantitative characteristic of landform evolution in catchment scale. In this paper, 5 m resolution DEMs and 3 arc-second resolution SRTM DEMs are used respectively to identify the impact factors of HI and its spatial variation in the Loess Plateau. Firstly, the geomorphologic meaning is discussed and summarized. The effect of DEM resolution and the analysis area in HI calculating is probed. With different DEM resolutions, the HI values derived could keep almost the same. When the area of catchment reaches 10 km2, the HI tends to be stable, which is regarded as a critical area for extracting HI in this study. Then, the geomorphic feature HI is proposed and the correlation of each kind of HI is calculated. There exist two feature groups in which the correlation coefficient is rather large. They are respectively catchment HI, positive terrain HI, shoulder line HI and peak HI, ridge line HI, and catchment boundary HI. Finally, the landform division based on HI is created through multiresolution segmentation in loess area. The coupling relationships exist in this division and water & soil loss map, sediment transport value map. The division in this paper refines the original map to a certain extent.