A coupled modeling framework to screen reclaimed water supplement schemes in an urban watershed

Abstract

Study region: The Daitou Creek Watershed in Tong’an District, Xiamen City, southeast coastal China Study focus: Reclaiming and reusing wastewater is a viable strategy to mitigate water shortages and improve water quality in riverine ecosystems. There is an urgent need for modeling approaches to provide data support for the implementation of river management strategies. A coupled modeling framework, integrating Soil and Water Assessment Tool (SWAT), Qual2K, and scenario analysis, was developed in this study to assess the potential of reclaimed water supplement in Daitou Creek Watershed during different seasons. New hydrological insight for the region: The utilization of proposed framework has resulted in the successful reproduction of riverine streamflow and nutrient dynamics across different seasons. An optimal reclaimed water supplement scheme was identified for remediation of riverine water quality in Daitou Creek. Water quality standards can be attained with the following minimum total volume of reclaimed water supplement upstream and downstream: 3 × 104 m3/d and 7.5 × 104 m3/d in wet season, 2 × 104 m3/d and 10 × 104 m3/d in average season, and 3 × 104 m3/d and 10 × 104 m3/d in dry season, respectively. Total phosphorus represents the dominant limiting factor in achieving water quality restoration, requiring more reclaimed water to decrease concentration compared to ammonia nitrogen. The proposed framework facilitates the identification of optimal reclaimed water supplement schemes, presenting urban watersheds with viable solutions for local riverine water quality degradation.

Keywords

• Coupled modeling
• Reclaimed water supplement
• Scenario analysis
• Water quality remediation
• SWAT
• Qual2K