国土空间开发“源汇”格局对河道水质的影响——以杭州市11个排水分区为例

INFLUENCE OF"SOURCE-SINK"PATTERN ON WATER QUALITY IN TERRITORIAL AND SPATIAL DEVELOPMENT:A CASE STUDY OF ELEVEN URBAN DRAINAGE ZONES IN HANGZHOU

以杭州市11个排水分区为研究单元,借鉴防治大气污染科学中的"源"、"汇"概念,建立土地利用的"源汇指数"与景观格局指数,采用主成分分析、皮尔逊相关分析、耦合分析等研究方法,研究国土空间开发对城市河道水质的影响。结论为,杭州市河道水质总体呈现"南好北差"的区域格局特征,其中氨氮(NH3-N)、总磷(TP)与氧化还原电位(ORP)是主要影响指标;商业用地、道路广场、耕地与碎片化的汇类用地结构是河道污染物含量上升的主要原因,但通过提高汇类用地的连接度、结合度与均匀度能起到有效的减缓作用;一个排水分区中满足水质达到Ⅲ类标准的源类用地控制占比应小于一定的阈值(本案杭州为33.3%);当景观破碎度高于n(本案杭州n值为0.85)时,汇类用地净化径流污染物的能力近乎丧失。这些结论为城市承载力研究和国土空间规划"双评价"提供了新的视角和思路。在此基础上,提出了国土空间开发建设过程中理想的城市星状布局概念形态,并从源头、过程和末端三个层面提出了土地利用与治水的策略建议。

Taking eleven drainage zones in Hangzhou as case study,the concepts of "source" and "sink" in the science of air pollution was introduced in this paper to establish the "source" and "sink" index of land use and index of landscape pattern by means of principal components analysis,Pearson correlation analysis,coupling equation,etc.,to study the influence of territorial and spatial development on urban water quality.It is concluded that:firstly,the water quality in Hangzhou generally appeared better in the south than that in the north,which were mostly affected by the indices of NH3-N,TP and ORP.Secondly,the commercial land,road and square,arable land,and fragmented sink-type land use structure were the main sources of water pollutants in city,which might be relieved by improving the CONNECT,COHESION,and SHEI.Thirdly,in order to meet the Ⅲ standard in a drainage zone,the proportion of source-type land use should be less than a certain threshold (33.3% for Hangzhou).Fourthly,the function of sink-type land use to purify some water pollutants would be lost when the value of fragmentation reached n (0.85 for Hangzhou).These conclusions provide a new perspective for the study of urban carrying capacity and the double evaluation of territorial and spatial development plan.Therefore,this paper proposed a star-shaped ideal layout in the process of territorial and spatial development and some suggestions on the source,process,and terminal of land use and water control.