随着流域城镇化的加速,流域城镇化景观格局对流域水质的影响逐渐加剧.以城镇化趋势明显的于桥水库流域为例,基于流域“源-汇”景观特征指数,并结合于桥水库流域2013、2014和2015年33个子流域的水质数据,采用空间分析、相关分析和冗余分析等方法,探讨了在城镇化影响下,于桥水库流域景观特征指数和水质指标的定量关系.结果表明:整个流域从上游到下游呈现“汇”景观面积减小,“源”景观面积增大的趋势,居民建设用地面积比在中下游子流域达34.6％,“汇”型景观中林地面积为33.5％;景观空间负荷对比指数(LWLI)全局Moran'sI的值为0.637,P＜0.01,在空间上存在趋于集群的现象,LWLI高-高聚集区与城镇化集中区域具有一致性.LWLI与流域氮、磷空间分布存在极显著的相关性,平水期TN与LWLI的复相关系数R2为0.811,丰水期LWLI与TP的复相关系数R2为0.741;子流域所有水质参数NH4-N、TN、NO3-N、TP及LWLI均集中在同一象限,与其它景观特征指数相比,LWLI对河流中氮、磷的影响最大.城镇居民用地与水质指标存在极显著的相关性,是流域水质污染重要的贡献源.流域城镇化发展中,建议提高村镇的景观连通性,便于污染物集中处理,同时增加林地、草地面积,改善流域的生态水文功能.%With the development of watershed urbanization,the impact of landscape pattern on river basin water quality has gradually increased.The types of pollution caused by urbanization are random,complex,and uncertain.Therefore,it is important to understand how a landscape pattern affects water quality in an urbanized watershed.The Yuqiao Reservoir is an important water source for the Luanhe-Tianjin Water Diversion Project.However,it is unclear how urbanization of the Yuqiao Reservoir watershed influences water quality.In this study,we investigated how the "source-sink" landscape pattern of the urbanized watershed affected nitrogen and phosphorus spatial variations in local rivers.This can potentially provide theoretical support for optimizing the landscape pattern in the Yuqiao Reservoir watershed.The main objective of this study was to identify the relationship between landscape pattern and water quality.The quantitative relationship between the landscape index and water quality was analyzed using landscape indices (including the location-weighted landscape contrast index (LWLI) combined with 33 water quality data for 2013-2015).The results showed that the amount of "sink" landscape,fell,but the amount of "source" landscape rose in the whole basin from upstream areas to downstream areas.The proportion of the land used for residential construction reached 34.6％ on average in the middle and lower sub-basin,and the forest area accounted for 33.5％ of the "sink" landscape.LWLI's Moran's I for the Yuqiao Reservoir watershed was 0.637 (P＜0.01),and this tended to cluster at the spatial scale.LWLI and the spatial patterns for nitrogen and phosphorus were significantly correlated.The coefficient of determination (R2) between the LWLI and total nitrogen (TN) was 0.811 during the normal-water period,and R2 was 0.741 during the high-water period.The NH4+-N,TN,NO3--N,TP,and LWLI water quality parameters tested in the sub-basins were gathered together in the fourth quadrant.LWLI had a greater effection nitrogen and phosphorus in the river than did other landscape pattern indices.It had widely distributed and apparently aggregating characteristics in urban residential land.Urban residential land surrounding Zunhua City was an important source of water pollution in the watershed.Identifying the quantitative relationships between landscape pattern and water quality indices is of theoretical and practical significance when attempting to optimize the regional landscape pattern and improve water quality.
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