The supply and demand of water purification service in an urbanizing basin on the Tibetan Plateau

Context Comprehensively quantifying the supply-demand relationship of water purification service (WPS) in the urbanizing basins is essential to optimize urban landscape patterns and improve water quality on the Tibetan Plateau (TP), but related research is still lacking. Objectives This study took the Huangshui River Basin (HRB) as an example to understand the supply-demand relationship of WPS in the urbanizing basins on the TP. Methods A combination of the statistical data and water purification model was used to quantify the WPS demand from point source pollution and non-point source pollution, as well as the WPS supply from water, vegetation and soil. Results Compared with the existing studies, the proposed method can quantify the supply-demand relationship of WPS more comprehensively and accurately, evidenced by the decrease of root mean square error from 1.00-1.96 to 0.68 and the increase of correlation coefficient from 0.50-0.53 to 0.66. We found that the demand was 44.7% higher than the supply in the HRB in 2019. The increase of urban point source pollution was discovered to be the main reason for such imbalance, while water shortage and flawed landscape configuration also played a role. Conclusions This study comprehensively quantifies the supply and demand of WPS and reveals that the supply-demand imbalance of WPS in the HRB had resulted in substandard water quality, threating local and downstream sustainability. Therefore, it is urgent to control the urban point source pollution and optimize the landscape configuration in this region.

Automated summary

This study comprehensively quantifies the supply and demand relationship of water purification service in urbanizing basins, revealing an imbalance that has resulted in substandard water quality. Urgent actions to control pollution and optimize landscape configuration are needed.