Preliminary study on the construction of evaluation index system of karst wetland degradation

There are large quantity of wetlands over the karst areas in southwestern China. Among them, the Huixian karst wetland is one of the largest karst wetlands, a largest natural wetland developed in the area with low-altitude and mid-latitude in the tropical and subtropical region. This wetland has played an important role in preserving water and ecological resources in the karst area. In recent years, due to the vulnerability of the karst wetland and the impact of human activities, the total area of the Huixian wetland has gradually reduced. As a result, the ecosystem of the wetland has been seriously damaged, characterized by severe degradation in ecological function. Thus, the protection and restoration of the Huixian karst wetland has become the focus of human attention. In order to better protect the wetland resources and ensure the health and sustainable development of the wetland, it is of great significance to construct an evaluation index system in line with the characteristics of the Huixian wet karst, and to conduct an objective, scientific and quantitative evaluation of the degradation of the Huixian wetland. In this study, firstly, we examined the unique karst characteristics in relation to the wetland, and then screened out the main factors affecting the health of the wetland.On this basis, the index system for the wetland assessment was established, using the Analytic Hierarchy Process (AHP) model in which the weight of each affecting factor was also determined. At the same time, through analyzing relevant research data and relevant standards associated with the wetland, the wetland degradation grades, together with evaluation methods, were proposed in this study. Finally a set of karst wetland degradation evaluation index system with 3 levels (target level, criterion level, index level) and 18 evaluation indexes was constructed. The construction of this index system fully combined the special hydrogeological driving factors of karst wetlands (rocky desertification, soil erosion, karst development, etc.) and the actual conditions of the wetland (geographical location, land use, etc.), with typical karst characteristics, which can be used in the health evaluation of typical karst wetlands and sustainable development protection, providing theoretical support for the protection and restoration of karst wetlands.