Abstract: Ecological buffer zone (EBZ) of lakes plays substantial role in intercepting pollutants and ecological restoration. In this study, based on the Sentinel-2 satellite data, the boundary of ecological buffer zone of Hongze Lake was delimited by using Phillips detention model targeting at non-point pollutions control. Finally, comparisons were conducted on the environmental performances of un-delimited, fixed-width and non-fixed width buffer zones by applying landscape ecological risk assessment. The results show that: (1) The width of the EBZ of Hongze Lake ranged from 2 to 60 m, accounting for 85.50% of the total. (2) Following the Technical guide for the protection and restoration of ecological buffer zones of rivers and lakes, the lakeshore was divided into six groups including: well-vegetated type, farmland-dominated type, aquaculture-dominated type, village-dominated type, urban-dominated type and estuarine-dominated type. The optimizing width values of EBZ for the aforementioned type of lakeshore with the goal of non-point sources pollution control were 57.62, 34.05, 32.79, 40.18, 38.99, and 22.99 m, respectively. (3) With the construction of a single landcover type, the non-fixed-width EBZ demonstrated a reducing effect on the ecological risk (ER) of Hongze lakeshore, whereas the ER of the fixed-width was estimated to be increased. The key factors affecting environmental performance of EBZ in Hongze Lake are slope and soil conditions. Therefore, it is essential for further implementation of EBZ that local government should pay attention to appropriate topographic adjustment and improvement in soil condition with the priority of delimiting of non-fixed width buffer zones. Meanwhile, ecological risk assessment should be conducted when delimiting fixed width buffer zone.

Key words: Hongze Lake, ecological buffer zone (EBZ), Phillips retention model, landscape ecological risk assessment