| 摘要: |
| 【目的】研究大汶河流域泰安段水量水质响应关系。【方法】依据大汶河流域泰安段7个水质站、1个水文站的逐月实测资料，采用季节性Kendall检验法对水质指标化学需氧量（COD）与氨氮（NH3-N）进行趋势分析，并用Copula函数构建水量与水质的二维、三维联合分布，系统分析水量水质变化规律。【结果】在时间上，2010—2019年大汶河流域泰安段COD与NH3-N的质量浓度均呈下降趋势，季节性Kendall检验结果显示71%的评价结果为高度显著下降趋势；在空间上，上游到下游的COD与NH3-N质量浓度呈下降趋势。大汶口站流量与水质关系表明，由非汛期到汛期，COD与NH3-N的质量浓度分别下降6%、37%，IV类水达标月份占比提高10%。Frank Copula函数的水量与水质二维联合分布研究表明，当流量与水质指标质量浓度增大时，联合概率值越大；当联合概率一定时，COD、NH3-N质量浓度随着流量的增大而降低，并趋于稳定；由联合概率等值线图可以判定任意流量下COD、NH3-N质量浓度的发生概率。Clayton Copula函数的水量与水质的三维联合分布研究表明，联合概率值小于0.6时，随着降水量、流量、水质指标质量浓度的增大，三者联合概率值增大，主要沿着流量增大的方向变化；当联合概率值大于0.6时，COD与NH3-N的三维联合概率的演变趋势发生变化。【结论】大汶河流域泰安段水量与水质存在密切关系，Copula函数适用于构建大汶河流域泰安段的水量水质的联合分布。 |
| 关键词: 流域；水质；水量；Copula联合分布 |
| DOI：10.13522/j.cnki.ggps.2021141 |
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| Change in Water Quality and Its Relationship to Water Quantity in Tai’an Section of the Dawen River Basin |
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HOU Enguang，et al
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(1. Hydrological Bureau of Tai’an City, Tai’an 271018, China; 2. Shandong Agricultural University, Tai’an 271018, China)
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| Abstract: |
| 【Background and objective】Quantity and quality are two indicators of water in a river basin and they are closely correlated. In general, a change in water quantity leads to a change in water quality, and the objective of this paper is to study their relationship in water at Tai’an section of the Dawen River Basin.【Method】Water quality data measured monthly from 2010—2019 at seven stations and flow rate at one hydrology station in the section were analysed using the Kendall test to identify the rends in the changes of chemical oxygen demand (COD) and ammonia nitrogen (NH3-N). The Copula function was used to construct two-dimensional and three-dimensional joint distributions of water quantity and quality to analyse their simultaneous variation.【Result】The concentrations of COD and NH3-N had both been in decline during the studied period, with the seasonal Kendall test showing that 71% of the evaluated results showing a downward trend. Spatially, the concentrations of COD and NH3-N decreased from upstream to downstream. At Dawenkou station, the concentrations of COD and NH3-N at wet seasons was reduced by 6% and 37% respectively, and monthly water quality that reached Class IV standard was increased by 10%, compared those measured in dry seasons The two-dimensional joint distribution of water quantity and quality calculated from the Frank Copula increased as the flow rate and water quality increased. When the joint probability was the same, the concentration of COD and NH3-N decreased asymptotically as the flow rate increased. The three-dimensional joint distribution of precipitation, water quantity and quality calculated from the Clayton Copula function showed that when its value was less than 0.6, the increase in the joint probability was induced predominantly by the increase in flow rate, while when the joint probability was greater than 0.6, the impact of COD and NH3-N increased.【Conclusion】There was a close relationship between water quantity and quality at Tai’an section of the Dawen River Basin. The Copula function was able to describe the joint distribution of water quantity and quality in the section. |
| Key words: dawen river basin; water quality; water quantity; Copula joint distribution |
