<p>The presence of fractures in discontinuous carbonate rock slopes affects the mechanical properties, which are vital for analyzing the deterioration of hydro-fluctuation belt. However, the spatial deterioration difference of rock mass discontinuities with the environment of reservoir water level fluctuation remains poorly understood. To investigate the deterioration of hydro-fluctuation belt, the phenomenon that the degree of water-rock interaction weakens with elevation is verified by the strength characteristics of the rock mass. Considering that chemical dissolution plays a non-negligible role in the deterioration of carbonate rock, the correlation was constructed between the spectral response based on chemical composition and the mechanical properties characterized by Schmidt hammer rebound value. The comparison shows that the normalized differential spectral index is optimal for describing this correlation. Subsequently, the discontinuities of rock mass can be distinguished as high hardness, low hardness, micro-fracture, and opening using the SG-CARS-PLS inversion model with nine characteristic wavelengths. The findings demonstrate that the characteristics of rock mass discontinuities can be quantified by the constructed spectral index. The development rate of the micro-fracture and opening areas obtained from spectral identification increases with the submergence frequency of water level. The deterioration of the carbonate rock slope progresses from micro-fractures to openings, and ultimately to the intersection of fractures. These evolutions are controlled by the stratification plane. As a result, identifying fractures on discontinuities is critical for assessing the deterioration of carbonate rock hydro-fluctuation belt. It serves as a warning sign of geological hazards in the Three Gorges Reservoir Area.</p>