the protective designs analyze the self-purify approach of nature water body, strengthen the purify function of water body type, improve the water body construction and biome by principle of resuming the water quality, and maintain water quality by the balance capacity of the system 保护性设计以水质恢复原理为指导,分析自然水体的自净途径,强化了水体形式的净化功能,完善水体结构与生物群落,依赖系统自身的平衡能力维持水体质量。