دانلود رایگان مقاله انگلیسی شناسایی پویایی خطر فرسایش خاک در کشش میانی رود زرد در چین از سال 1978 تا سال 2010 - اشپرینگر 2018

Abstract:

Soil erosion has become a significant environmental problem that threatens ecosystems globally. The risks posed by soil erosion, the trends in the spatial distribution in soil erosion, and the status, intensity, and conservation priority level in the middle reaches of the Yellow River Basin were identified from 1978 to 2010. This study employed a multi-criteria evaluation method integrated with GIS and multi-source remote sensing data including land use, slope gradient and vegetation fractional coverage (VFC). The erosion status in the study region improved from 1978 to 2010; areas of extremely severe, more severe, and severe soil erosion decreased from 0.05%, 0.94%, and 11.25% in 1978 to 0.04%, 0.81%, and 10.28% in 1998, respectively, and to 0.03%, 0.59%, and 6.87% in 2010, respectively. Compared to the period from 1978 to 1998, the area classed as improvement grade erosion increased by about 47,210.18 km2 from 1998 to 2010, while the area classed as deterioration grade erosion decreased by about 17,738.29 km2 . Almost all severe erosion regions fall in the 1st and 2nd conservation priority levels, which areas accounted for 3.86% and 1.11% of the study area in the two periods, respectively. This study identified regions where soil erosion control is required and the results provide a reference for policymakers to implement soil conservation measures in the future.

7 Conclusions

Based on GIS techniques, this study integrated a multi-criteria evaluation approach involving high-spatial-resolution remote sensing data (slope gradient, VFC, and land use) to qualitatively identify the trends in the spatial distribution of soil erosion risk in the middle reaches of the Yellow River Basin from 1978 to 2010.

The results show that erosion risk has decreased over the 33-year study period. From 1978 to 1998, the areas categorized as having extremely severe, more severe, and severe erosion risk decreased by 0.01%, 0.13%, and 0.97% of the study area, respectively; the respective decreases were 0.01%, 0.22%, and 3.41%. The decreasing trend from 1998 to 2010 was more pronounced than that from 1978 to 1998.

The results also indicate that from 1978 to 2010 the total area classed as deterioration grade erosion was smaller than that classed as improvement grade erosion, and that the transformation between these classes between 1998 and 2010 was smaller than that between 1978 and 1998. From 1978 to 1998, the proportions of the region where the erosion grade changed from severe to slight and from severe to light were 0.16% and 0.13%, respectively, and the proportions of regions where the erosion grade changed from slight and light to extremely severe and severe were all less than 0.01%. From 1998 to 2010, the proportions of regions where the erosion grade changed from severe to slight and from severe to light were 0.97% and 1.15%, respectively, and the proportions of regions where the erosion grade changed from slight or light to extremely severe or severe were all less than 0.01%. The proportions of extremely severe and more severe erosion grades were all less than 0.01% of the total area from 1978 to 1998 and from 1998 to 2010, but these values were greater from 1998 to 2010 than from 1978 to 1998.