Identification of the control factors affecting water quality variation at multi-spatial scales in a headwater watershed
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RESEARCH ARTICLE
Identification of the control factors affecting water quality variation at multi-spatial scales in a headwater watershed Jianhong Wu 1,2 & Yanan Jin 1 & Yun Hao 1 & Jun Lu 1,2,3 Received: 23 April 2020 / Accepted: 20 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Understanding the effect of landscape characteristics on water quality can provide insight into mitigating water quality impairment. However, there is no consensus about the key controlling factors influencing water quality. This paper examined the combined effects of land use and topography on water quality across multi-scale, and identified the key controlling factors determining water quality variation in the headwater watershed of the Hengxi reservoir in Eastern China. Water quality impairment (WQI), expressed as a composite variable, was established to measure the overall water quality. We used the partial least squares (PLSR) method to explore the combination of landscape metrics and identify the key controlling factors. Results showed that the optimal PLSR model at 50-m, 100-m, and 150-m buffer scales and catchment scale explained 77%, 63%, 60%, and 56% of variability in WQI, respectively. At catchment scale, patch density, the percentage of paddy field, and hypsometric integral were the key controlling factors impacting water quality. At buffer scales, the slope gradient, the percentage of forest land, and topographic wetness index were more effectively determined WQI variation. Thus, the key controlling factors depend on spatial scales. Both spatial scales and corresponding key controlling factors should be considered in the adjustment of land use composition and planning of landscape configuration to better protect water quality. Keywords Water quality . Land use composition . Land use configuration . Topographical metrics . Spatial scales . Partial least squares regression
Introduction Headwater streams are important sources of cleaner water. Despite their relatively small dimensions, they played an important role in sustaining the ecological function of the entire watershed (Zhang et al. 2018; Staponites et al. 2019). Water Responsible Editor: Xianliang Yi Supplementary Information The online version contains supplementary material available at https://doi.org/10.1007/s11356-02011352-4. * Jun Lu [email protected] 1
College of Environmental and Natural Resources, Zhejiang University, Hangzhou 310058, People’s Republic of China
2
Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, Zhejiang University, Hangzhou 310058, China
3
China Ministry of Education Key Lab of Environment Remediation and Ecological Health, Zhejiang University, Hangzhou 310058, China
quality of headwater streams is important, because headwaters are the first line of defense against potential contaminants such as excess nutrients, and the deterioration of water quality in headwater streams can affect the water quality of the entire watershed (Wohl 2017). However, the water quality of relatively
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