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首页> 外文期刊>Water resources research >Time series and recurrence interval models to predict the vulnerability of streams to episodic acidification in Shenandoah National Park, Virginia
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Time series and recurrence interval models to predict the vulnerability of streams to episodic acidification in Shenandoah National Park, Virginia

机译：时间序列和递归间隔模型可预测弗吉尼亚州谢南多厄国家公园的溪流易发性酸化

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Acid rain affects headwater streams by temporarily reducing the acid-neutralizing capacity (ANC) of the water, a process termed episodic acidification. The increase in acidic components in stream water can have deleterious effects on the aquatic biota. Although acidic deposition is uniform across Shenandoah National Park (SNP) in north central Virginia, the stream water quality response during rain events varies substantially. This response is a function of the catchment's underlying geology and topography. Geologic and topographic data for SNP's 231 catchments are readily available; however, long-term measurements (tens of years) of ANC and accompanying discharge are not and would be prohibitively expensive to collect. Transfer function time series models were developed to predict hourly ANC from discharge for five SNP catchments with long-term water-quality and discharge records. Hourly ANC predictions over short time periods ( ≤ 1 week) were averaged, and distributions of the recurrence intervals of annual water-year minimum ANC values were model-simulated for periods of 6, 24, 72, and 168 hours. The distributions were extrapolated to the rest of the SNP catchments on the basis of catchment geology and topography. On the basis of the models, large numbers of SNP streams have 6- to 168-hour periods of low-ANC values, which may stress resident fish populations. Smaller catchments are more vulnerable to episodic acidification than larger catchments underlain by the same bedrock. Catchments with similar topography and size are more vulnerable if underlain by less basaltic/carbonate bedrock. Many catchments are predicted to have successive years of low-ANC values potentially sufficient to extirpate some species.
机译：酸雨会暂时降低水的酸中和能力（ANC），从而影响源头水流，这一过程称为间歇酸化。溪流水中酸性成分的增加会对水生生物群产生有害影响。尽管弗吉尼亚北部中部的雪兰多厄国家公园（SNP）的酸性沉积物是均匀的，但在降雨事件中溪流水质响应却大不相同。该响应是集水区基础地质和地形的函数。 SNP的231个流域的地质和地形数据随时可用；然而，对ANC的长期测量（数十年）及其伴随的排放并不是很昂贵，而且收集起来成本过高。开发了传递函数时间序列模型，以预测具有长期水质和流量记录的五个SNP集水区的流量每小时的ANC。对短时间段（≤1周）中每小时的ANC预测值进行平均，并针对6、24、72和168小时的时段模拟水年度年度最小ANC值的重复间隔分布。根据集水区地质和地形，将分布推算到SNP的其余集水区。在模型的基础上，大量的SNP流具有6到168小时的低ANC值，这可能会给常驻鱼类种群带来压力。较小的集水区比同一个基岩下的较大的集水区更容易遭受突发性酸化。如果被较少的玄武岩/碳酸盐岩床所覆盖，则具有相似地形和大小的集水区更容易受到影响。预计许多流域将连续多年出现低ANC值，可能足以消灭某些物种。

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