多维视角下水生态修复分区划定——以典型喀斯特地区河池市为例

Delineation of water ecological restoration zoning from a multi-dimensional perspective:A case study in Hechi,a typical karst region

水生态修复分区向上衔接水生态系统修复目标,向下引导修复工程的空间布局,是实现水资源要素系统修复的关键。当前,水生态修复分区面临层级体系不一、指标不全面、边界模糊等问题,因此,本研究以喀斯特生态脆弱区广西河池市为例,构建“流域自然单元-主导生态功能-生态胁迫风险”的多维分区体系框架。一级分区选取河流水系和地貌类型作为划分指标,识别子流域单元作为一级分区边界;二级分区采取“自上而下”的划分方法,在承接流域自然地理特征的基础上,明确水生态修复的目标,选取水源涵养、生物多样性和景观文化服务3项指标进行评价,利用K-means聚类方法对空间单元内的主导生态功能进行识别,以子流域单元作为二级分区边界;三级分区是生态修复工程的具体实施单元,选取水土流失、洪涝风险和人类干扰3项指标表征水生态系统面临的外部胁迫风险,进行三级分区划定。共划定11个水生态一级分区、4个二级分区和3个三级分区,综合流域自然地理格局、主导生态功能、生态胁迫风险的空间分异特征的三级分区结果,并结合子流域单元和乡镇行政单元确定分区边界,最终将水生态修复分区综合划分为5类、32个子生态分区,并分区、分类提出相应的生态修复策略。

Water ecological restoration zoning,which involves articulating goals for restoring water ecosystems upwards and guiding the spatial layout of restoration projects downwards,is key to achieving systematic restoration of water resource elements.There are many challenges in water ecological restoration zoning,including disparate hierarchical systems,incomplete indicators,and vague boundaries.With Guangxi Hechi,a karst ecologically fragile region,as a case,we developed a multidimensional zoning system framework based on“watershed natural unit-dominant ecological function-ecological stress risk”.The first-level zoning employed river systems and geomorphic types as indicators and delineated the sub-watershed unit as the boundary.The second-level zoning adopted a“top-down”division method to clarify the goal of water ecological restoration based on watershed natural geography and select three indicators(water conservation,biodiversity,and landscape cultural services)for evaluation.We used the K-means clustering method to identify dominant ecological functions in spatial units,with the sub-watershed unit demarcating second-level zoning boundaries.The third-level zoning was the specific implementation unit for ecological restoration projects.We used three indicators(soil erosion,flooding risk,and human interference)to characterize water ecosystem risk from external coercion,and defined the third-level zoning.We delineated 11 primary water ecological zones,four secondary zones,and three tertiary zones.Synthesizing tertiary zoning results accounted for spatial differentiation characteristics of watershed natural geography,dominant ecological functions,and ecological coercion risks,and combining sub-watershed and township administrative units determined zoning boundaries,water ecological restoration zoning was comprehensively classified into five categories and 32 sub-ecological zones.Corresponding ecological restoration strategies were proposed based on zoning and classification.