Abstract
The Yunnan–Guizhou Plateau (YGP) is a typical ecologically fragile region in southwest China. Water-erosion desertification (WED) is one of the most significant environmental and socio-economic issues on the YGP and has seriously restricted the socio-economic development of this region. However, the research on monitoring of the desertification trends in this region has been limited to long time-series Landsat imagery. The objectives of this research were to monitor the WED trends on the YGP using time-series Landsat imagery data from 1989 to 2016. In this paper, we present a multi-indicator rule-based method, which was used to map the WED on the YGP during this period. The results show that the addition of multiple indicators improved the WED classification accuracy to 90.61%. Overall, the following results were obtained by using the proposed method. (1) The slight desertification area on the YGP increased from 89,617.09 km2 in 1989 to 100,976.47 km2 in 2016 with an annual growth ratio (AGR) of 0.48%, the moderate desertification area increased from 80,276.65 km2 in 1989 to 90,768.39 km2 in 2016 with an AGR of 0.50%, and the severe desertification area increased from 8149.3 km2 in 1989 to 13,220.16 km2 in 2016 with an AGR of 2.39%. (2) The WED expansion on the YGP can be divided into three stages. Firstly, the total WED area increased slowly from 17.80×104 km2 in 1989 to 17.98×104 km2 in 2010 with an AGR of 0.05%. Then, the WED rapidly expanded from 17.98×104 km2 in 2010 to 20.28×104 km2 in 2013 with an AGR of 4.26%. Finally, the WED increased slightly from 20.28×104 km2 in 2013 to 20.50×104 km2 in 2016 with an AGR of 0.36%. The total areas of the different degrees of WED decreased in 1992, 1998, 2001, and 2004. (3) The driving factors of WED were analyzed based on the Geographically Weighted Regression (GWR) model. We found that precipitation, vegetation area, and gross domestic product have key roles in the processes of desertification reversion and development. However, the regression coefficients between WED and these factors exhibited considerable spatial variations. The regression coefficients of the key driving factors showed different spatial distributions based on the GWR model in the YGP. The research results can provide scientific reference information for the prevention and control of WED in the YGP.
Highlights
Water-erosion desertification (WED) is a special type of land desertification due to soil erosion [1,2,3,4,5], which is mainly distributed in the Loess Plateau and Yunnan–Guizhou Plateau (YGP)
(1) The slight desertification area on the YGP increased from 89,617.09 km2 in 1989 to 100,976.47 km2 in 2016 with an annual growth ratio (AGR) of 0.48%, the moderate desertification area increased from 80,276.65 km2 in 1989 to 90,768.39 km2 in 2016 with an AGR of 0.50%, and the severe desertification area increased from 8149.3 km2 in 1989 to 13,220.16 km2 in 2016 with an AGR of 2.39%. (2) The WED expansion on the YGP can be divided into three stages
Long-term monitoring of WED was achieved on a large scale using time-series Landsat images, and the WED monitoring results show that the proposed method outperformed the other approaches in terms of Overall Accuracy (OA) and kappa
Summary
Water-erosion desertification (WED) is a special type of land desertification due to soil erosion [1,2,3,4,5], which is mainly distributed in the Loess Plateau and Yunnan–Guizhou Plateau (YGP). The WED in the karst regions is called rocky desertification. The rocky desertification in karst regions means to the loss of surface soil due to soil erosion by rain or stripped by water. The WED has seriously harmed the ecological environment, natural resources, and socio-economic development on the YGP[10], so WED prevention and control are critically important and urgent in this area. Monitoring WED trends is an important and effective means of combating desertification on the YGP. Traditional WED monitoring methods rely on ground surveys, which are labor intensive, time consuming, and expensive and limit time series comparisons and regional-scale research[11]. With the development of remote-sensing technology, it has become possible to monitor desertification trends for long time series and large areas
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