Abstract
Water quality assessment is an important foundation of water resource protection and is affected by many indicators. The dynamic and fuzzy changes of water quality lead to problems for proper assessment. This paper explores a method which is in accordance with the water quality changes. The proposed method is based on the variable fuzzy pattern recognition (VFPR) model and combines the analytic hierarchy process (AHP) model with the entropy weight (EW) method. The proposed method was applied to dynamically assess the water quality of Biliuhe Reservoir (Dailan, China). The results show that the water quality level is between levels 2 and 3 and worse in August or September, caused by the increasing water temperature and rainfall. Weights and methods are compared and random errors of the values of indicators are analyzed. It is concluded that the proposed method has advantages of dynamism, fuzzification and stability by considering the interval influence of multiple indicators and using the average level characteristic values of four models as results.
Highlights
Water is essential for peoples’ health and socioeconomic development
Talalaj used a modified water quality index (WQI) method to study the change in groundwater quality, and the results showed that the highest WQI value was recorded in summer, while the lowest was in March [2]
This paper explores a method based on the variable fuzzy pattern recognition (VFPR) model, and the proposed method is used to dynamically assess water quality
Summary
Water is essential for peoples’ health and socioeconomic development. With the improvement of living standards, people have put efforts into safeguarding sufficient quantities of water resources, but have paid more attention to increasing water quality. Comprehensive assessment of water quality has attracted a lot of interest. Changes of water quality state or level are driven by the interacting influences of physical, chemical and microbiological indexes. Variations of external circumstances result in the dynamic change of water quality. Seasonal variations change the water temperature and water surface conditions, and further influence the distribution of dissolved oxygen in depth; rainstorms bring lots of pollutants into the water, which might increases the total phosphorus content, and changes the hydraulic conditions [5,6,7]. In order to reasonably assess water quality, researchers have developed a series of methods to study the state of water quality. Talalaj used a modified WQI method to study the change in groundwater quality, and the results showed that the highest WQI value was recorded in summer, while the lowest was in March [2]
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