Ecological environment quality evaluation of the gully area in the Loess Plateau based on remote sensing ecological index

Abstract

Abstract: As the fundamental foundation for human survival and development, the ecological environment is an important guarantee for social progress. With the accelerated development of society, the impact of human activities on the ecological environment has become increasingly significant. Fu County (4,182 km2) is located in the gully area of the Loess Plateau, an important ecological security barrier in the north of China. Clarifying the current situation of the ecological environment and the temporal and spatial changes of ecological environment quality in Fu County is conducive to the construction of ecological civilization. It provides scientific support to improve ecological quality. Based on the remote sensing images of Landsat in Fu County from 1992 to 2019, we considered four indexes of Normalized Difference Vegetation Index (NDVI), Tasseled Cap Transformation Humidity Index (Wet), Normalized Difference Bare Soil Index (NDBSI), and Land Surface Temperature (LST) to represent greenness, humidity, dryness and heat of the environment. The principal component analysis was uesd to establish a remote sensing ecological index model (RSEI). And then we evaluated the ecological quality in the area in the past 30 years.The results showed that: (1) The average correlation between RSEI and four indexes was 0.874, which means RSEI can comprehensively reflect the ecological environment quality status of the study area compared with a single index. (2) The regional mean values of RSEI in Fu County showed an upward trend from 0.621 to 0.806 between 1992 and 2019, and the increase in ecological environment quality gradually increased from northwest to southeast of the county. (3) The increasing area and magnitude of the ecological level of the county from 1992 to 2019 were much greater than the decling area and magnitude. Over the past 30 years, the relatively sparsely populated townships of Zhiluo, Niwu and Zhangjiawan, which have a high degree of vegetation cover, have always been in a better state, while the densely populated townships of Jizixian, Jiaodao and Yangquan has always been poor. From the perspective of the degree of change in the quality level of the ecological environment, all townships have been improved to different degrees, and the improvement is the most obvious in Jizixian Town, Jiaodao Town and Yangquan Town. The improvement of ecological environment quality level from good to excellent is probably because that the implementation of many ecological projects and the increase in rainfall, and the decrease in bare soil area and surface heat decreased in Fu County in the past 30 years.This study can provide method reference and data support for ecological environment monitoring, governance and protection.   Keywords: Fu County; Ecological environment quality evaluation; RSEI; Dynamic monitoring