Landscape fragmentation of built-up land significantly impact on water quality in the Yellow River Basin

Jinghui Dou; Rui Xia; Kai Zhang; Chao Xu; Yan Chen; Xiaoyu Liu; Xikang Hou; Yingze Yin; Lina Li

doi:10.1016/j.jenvman.2024.123232

Landscape fragmentation of built-up land significantly impact on water quality in the Yellow River Basin

J Environ Manage. 2024 Nov 11:371:123232. doi: 10.1016/j.jenvman.2024.123232. Online ahead of print.

Authors

Jinghui Dou¹, Rui Xia², Kai Zhang³, Chao Xu³, Yan Chen⁴, Xiaoyu Liu⁵, Xikang Hou⁵, Yingze Yin⁶, Lina Li⁷

Affiliations

¹ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; National Joint Research Center for Ecological Conservation and High Quality Development of the Yellow River Basin, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; Northwest University College of Urban and Environmental Sciences, Northwest University, Xi'an, 710127, China.
² State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; National Joint Research Center for Ecological Conservation and High Quality Development of the Yellow River Basin, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China. Electronic address: [email protected].
³ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; National Joint Research Center for Ecological Conservation and High Quality Development of the Yellow River Basin, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
⁴ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; National Joint Research Center for Ecological Conservation and High Quality Development of the Yellow River Basin, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China.
⁵ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
⁶ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; Upper and Middle Yellow River Bureau, YRCC, Xi'an, 710021, China.
⁷ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; School of Water Conservancy Science and Engineering, Zhengzhou University, Zhengzhou, 450001, China.

PMID: 39531767
DOI: 10.1016/j.jenvman.2024.123232

Abstract

Urbanization development often leads to significant changes in the extent in area and fragmentation of built-up land landscape pattern (BLLP) in river basins, which greatly impact the processes of rainfall runoff and pollutant migration. Understanding the spatial scale effects and driving mechanisms of BLLP changes on water quality in large river basins is a challenging research topic and an international frontier in the interdisciplinary fields of geography and environment. This study analyzes the spatial variations of BLLP and water quality throughout the Yellow River Basin (YRB) during the rainy seasons from 2019 to 2021 (4 h scale). Utilized the random forest model to quantitatively separates the contributions of rainfall processes to surface runoff and water pollution, revealing the scale effects and non-linear driving mechanisms of BLLP impacts on water environment changes. The results indicate that: 1) The YRB exhibits great spatial heterogeneity in terms of both BLLP and water quality, with places with lower water quality displaying bigger areas and higher degrees of BLLP fragmentation. 2) The patch density and built-up land area (PD.B and CA.B) have a major impact on changes in water quality in the YRB, with notable impacts noted in circular buffer zones with radii of 20 km and 5 km, respectively. 3) PD.B is sensitive to water quality in the YRB, explaining 39.1%-49.5% of the variance under different rainfall conditions, and exhibits a significant non-linear relationship, with an impact threshold of 0.38 (n/100 ha). The study suggests that for large-scale regions like the YRB, the degree of BLLP fragmentation is more likely to lead to degradation of water environmental quality compared to its area. BLLP fragmentation due to higher PD.B and CA.B disrupts the original ecosystem and hydrological connectivity, resulting in poorer retention and filtration of pollutants carried by rainfall runoff, while increasing the export of other pollutants. However, once urbanization surpasses a certain threshold, the BLLP fragmentation can enhance water quality by reducing the impermeable surface connectivity, as they are no longer impacted by expanding areas. To achieve ecologically sustainable development, it is necessary to apply rational landscape management and water resource management policies that consider the dual process of how BLLP fragmentation affects the water environment.

Keywords: Landscape pattern; Machine learning; Rainfall; Urbanization; Water quality; Yellow River Basin.