Wetland Restoration Suitability Evaluation at the Watershed Scale- A Case Study in Upstream of the Yongdinghe River

Recently, wetland restoration has received increased attention due to multiple and valuable environmental services provided by wetlands. However, most studies have specifically focused on undertaking restoring strategies, such as improving water quality, protecting biodiversity or utilizing flood, without considering the interaction among different wetlands in a whole watershed, such as river connectivity and flow continuity. And the special effects on the restoration performance and management implications are not fully evaluated. Thus, it is needed to evaluate potential effects of wetland restoration activities in a watershed scale, in order to find suitable wetland restoration sites. This paper proposes a GIS-based multi-criteria comprehensive evaluation methodology for wetland restoration suitability evaluation, by taking upstream of the Yongdinghe River as the example. It includes three steps: criteria information extraction, criteria value assignment and normalization, and integrated evaluation. For the first step, the stream order, overland flow length, stream water quality, saturation index, hydric soil and land use were selected as the evaluation criteria. In the second step, unique value was assigned to each criterion according to their potential contribution to the restoration. And all the criteria were normalized in order to eliminate errors that may result from different dimensions. In the final step, the weight of each criterion was calculated and the integrated criterion was deduced by using the AHP method. The restoration suitability prioritization of the wetlands was classified into 5 levels: lowest, low, middle, high, highest by using the histogram segmentation method. And the evaluation accuracy was verified with the Precedence Chart Method. The statistical result shows that about 979 km2 wetlands in the overall study area has the highest suitability for restoration, accounting for 2.18% of the total area. And most of them are located in Yangyuan country, with an area of about 131.586 km2. The main types of wetlands are reservoir wetland and river wetland. They are accounting for 11.75% and 11.33% of the total area, respectively.