Assessment of Urban Blue-Green Space Landscape Ecological Health Based on the GST-AHP-TOPSIS Composite Model

The urban blue-green space landscape ecology is an important component that supports the urban landscape ecosystem. In this study, a combination model of the grey system theory (GST), analytic hierarchy process (AHP), and technique for order of preference by similarity to ideal solution (TOPSIS) was used to construct criteria layers from the following four aspects: green space vegetation coverage, ecosystem diversity, air and water quality, social participation, and health. The GST method was employed to screen evaluation indicators, the AHP method was used to calculate the weight of each indicator, and finally, TOPSIS was applied for weighted ranking to verify the scientific and rationality of the evaluation system. The results indicated the following: (1) out of 36 indicator factors, 10 were not selected through the GST method; (2) the weight ranking of the criteria layer was as follows, from highest to lowest: D₂ ecosystem diversity 0.4816 > D₁ green space vegetation coverage 0.2608 > D₃ air and water quality 0.1864 > D₄ social participation and health 0.0713; and (3) the relative closeness and ranking of different regions in Jinan city were as follows: Da Ming Hu area > Shan Da Lu area > Gu Cheng area > Shang Bu area. This study can help avoid decision-making errors caused by subjective factors and provide new approaches for the assessment of the ecological health of urban blue-green space landscapes.