Estimation of desertification risk from soil erosion: a case study for Gansu Province, China

Abstract

Desertification is of increasing concern over recent decades. A methodology based on soil erosion from water and wind is developed, to evaluate desertification risk. The approach includes utilization of both the Universal Soil Loss Equation and the Wind Erosion Equation developed by California Air Resources Board. The desertification risk is mapped using ArcGIS techniques and is compared with the assessment from the environmentally sensitive areas model. The methodology, applied to Gansu as a case study, one of the driest regions in China, indicates that severe desertification is occurring in the Province, particularly through wind erosion. Approximately one-half the land areas in Gansu will experience high risk of desertification, especially in the western regions. The mean water and soil erosion in Gansu is 0.05 tonnes/ha and 44 tonnes/ha per year, respectively. The maximum per hectare soil loss through wind erosion is estimated as thirty times larger compared with water erosion. Improvements in vegetative cover as well as cropping methods would significantly reduce the high risk of desertification from 46 % of Gansu to less than 10 %. The analysis also shows that desertification is sensitive to climate and terrain slopes, and that human influences such as land use and population density can aggravate the degrees of desertification.