Abstract: A rapid and accurate assessment of regional eco-environmental quality and its change is of important reference to ecological monitoring in the karst rocky desertification region. With Xiushan County in Chongqing as research area and the Landsat 5/8 imagines as main data resources, the eco-environmental quality and its change in the Xiushan County were assessed by establishing modified remote sensing ecological distance index (MRSEDI), which was calculated by rocky desertification index (RI), normalized difference built-up and soil index (NDSI), wetness index (WI), and normalized difference vegetation index (NDVI). Results unveiled that: 1) The average values of MRSEDI in 1990, 2002 and 2016 were 0.617, 0.665 and 0.748, respectively, presenting a rising trend. 2) The area of excellent and good eco-environmental quality in the research area increased over the 26 years, from 55.94% in 1990 to 82.67% in 2016. 3) The eco-environmental quality in most of the study area changed for the better or remained unchanged over the 26 years. The improved area accounted for 54.01%, while the unchanged area occupied 34.49%. In conclusion, Xiushan county boasts a good and ever-improving eco-environmental quality, implying that the eco-environmental protection measures over the 26 years are effective.

Key words: eco-environmental quality, assessment, MRSEDI, rocky desertification index, Xiushan County