Study of the KRD spatial distribution pattern in the southern Nandong underground river drainage

Based on the GF-1 WFV remote sensing data of September 29, 2016, we carried out a Karst Rocky Desertification (KRD) remote sensing survey in the southern Nandong underground river drainage. Using the Normalized Difference Vegetation Index (NDVI) and Fractional Vegetation Index (FVC) we extracted the KRD information on KRD, obtaining its distribution pattern in the research region. The results show that the KRD occurrence ratio reaches 74.55%, indicative of a high degree of KRD. In this area, moderate KRD is most developed, with proportion of 32.63%. The serious KRD is the least ratio, only 17.59%. We made an analysis of the correlation between KRD and four factors, i.e. lithology, elevation, slope and aspect, yielding the KRD occurrence changing regularities to each factor. The results show that KRD developed relatively well in the places of the low altitude, gentle slopes and the pure carbonate, while different aspects have no significant correlation with KRD generation.