River Health Assessment Method Based on Water Quality Indices for the Dagujia River in China

River health has become one of the major concerns today. This study develops a water quality index-based health assessment method to diagnose the status of the Dagujia River, China. The Dagujia River is the second largest river and the main source of drinking water in Yantai, China. The health status is classified into five levels – ideal, healthy, sub-healthy, unhealthy, and morbid. The assessment process includes four phases: 1) index layer grading, 2) criterion layer grading, 3) target layer grading, and 4) health diagnosis. The results show that eight sections are morbid, accounting for 66.3% of the entire assessed river. It also finds that higher water temperature variation ( WTV ) results in this poor health situation. However, the assessment excluding WTV reveals that all the other sections are in ideal states except for a sub-healthy river section caused by the higher concentrations of CODMn and COD in the high-flood season (June–September).