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| DOI：10.13522/j.cnki.ggps.2025157 |
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| Variation in water quality of the Hongyashan Reservoir |
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CHU Jiju, JIANG Yajun, CHU Jihua, ZHOU Weida
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Gansu Province Wuwei Hydrology and Water Resources Survey Center, Wuwei 733000, China
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| Abstract: |
| 【Objective】Hongyashan Reservoir, located in the lower reaches of the Shiyang River Basin in Northwestern China, is a critical regional water source. However, its water environment has changed under the influence of climate change and human activities. This study systematically analyses the variation in water quality of the reservoir. 【Method】The analysis was based on water quality data measured from 2002 to 2022 in the reservoir. Descriptive statistical analysis and trend detection methods were used to examine ① temporal dynamics of water quality indicators; ② inter-annual variation in concentrations of major pollutant concentrations, including ammonia nitrogen, five-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), and total phosphorus (TP). Reservoir water quality was classified based on the ‘Surface Water Environmental Quality Standard (GB 3838-2002) of China’. 【Result】① The inter-annual variation in the reservoir water quality was stable, with water chemistry dominated by Class C Ca Group II. However, chloride, mineralization, total hardness and total alkalinity all showed a significant increase (p＜0.05) from 2002 to 2022. ② Prior to 2016, the dominant pollutants in the reservoir were ammonia nitrogen, BOD2, and COD. Since 2016, these concentrations have decreased significantly, and water quality has improved sustainably. ③ In the study period, total phosphorus remained high, with no sign of decline. 【Conclusion】From 2002 to 2022, the water quality of Hongyashan Reservoir improved due to effective point source pollution control. Nevertheless, TP and water salinity remain high, and it is imperative to strengthen agricultural pollution management and optimize reservoir operation to reduce inflow of these pollutants. |
| Key words: Hongyashan Reservoir; factor analysis; characteristics of water quality variation |
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