不同时空计算尺度对水环境容量评估差异的影响分析

Analysis of the Impact of Different Spatial and Temporal Calculation Scales on Differences in Water Environmental Capacity Assessment

水环境容量常以90%保证率最枯月流量作为计算条件,又容易忽略其空间分布差异,故易导致“过保护”或工程建设成本过大等问题。考虑河道流量及污染物入河量的时空变化特点,本文以江西省九江市两河流域为例,研究了不同时空计算尺度对水环境容量评估差异的影响。结果表明,随着时间尺度的增加,全年的水环境容量变化范围缩小,差异性降低;空间尺度变化对两河的水环境容量影响较小,但同一尺度下各个子计算单元的理想水环境容量呈现出上游至下游逐渐增大的趋势;不同时空尺度下动态水环境容量能客观反映水环境容量的实际变化特征,能为水环境保护工程提供建设依据。

The water environment capacity is often calculated based on the lowest monthly flow rate with a 90%guarantee rate,and its spatial distribution differences are easily ignored,so it is easy to cause problems such as"over-protection"or excessive engineering construction costs.Considering the temporal and spatial variation characteristics of river flow and pollutants entering the river,this paper takes the two river basins in Jiujiang City,Jiangxi Province as an example,and studies the impact of different temporal and spatial calculation scales on differences in water environmental capacity assessment.The results show that with the increase of the time scale,the variation range of the annual water environment capacity is narrowed,and the difference is reduced;the spatial scale change has little effect on the water environmental capacity of the two rivers,but the ideal water environmental capacity of each sub-computing unit at the same scale shows a trend of increasing from upstream to downstream;the dynamic water environment capacity at different temporal and spatial scales can objectively reflect the actual change characteristics of the water environment capacity,and can provide a construction basis for water environmental protection projects.