Modelling transport of dissolved silica in a forested headwater catchment: the effect of hydrological and chemical time scales on hysteresis in the concentration–discharge relationship
Modelling transport of dissolved silica in a forested headwater catchment: the effect of hydrological and chemical time scales on hysteresis in the concentration–discharge relationship
复制标题
模拟森林源头集水区中溶解二氧化硅的传输：水文和化学时间尺度对浓度-流量关系滞后的影响
DOI：
10.1002/hyp.254
复制
发表时间：
2001
影响因子：
3.2
通讯作者：
Jeff P. Raffensperger
中科院分区：
文献类型：
--
作者：
G. Hornberger;T. Scanlon;Jeff P. Raffensperger
河流中浓度c和流量q之间的关系是水化学集水响应的一个方面，已被广泛用于诊断。具体地，c-q曲线中的环，通常被称为滞后环，用于推断特定的混合模式。在弗吉尼亚州谢南多阿国家公园的Brokenback Run南福克(SFBR)，我们有证据表明，溪流动力学反映了一个由栖息在常年地下水位之上的短暂地下暴雨带组成的系统。溶解二氧化硅与水流流量的关系在顺时针方向上表现出滞后现象。在具有恒定浓度端元的三组分混合的情况下对这种关系进行建模，未能重现观察到的c-q模式。在这篇文章中，我们研究了土壤-水中二氧化硅浓度的时间变化可以解释C-Q曲线中如何出现CW滞后环的可能性。特别是，我们研究了水文时间尺度与化学时间尺度的比率在确定滞后环性质方面的作用。只有当化学(淋溶)时间常数小于(或仅略大于)水文时间常数时，我们在SFBR中观察到的CW循环才能用土壤-水浓度的时间变异性来解释。这些时间常数的近乎相等与水文测量和淋溶实验的报告是一致的。版权所有©2001 John Wiley&Sons，Ltd.
The relationship between concentration c and discharge Q in a stream is one of the aspects of hydrochemical catchment response that has been used widely as a diagnostic. In particular, loops in the c–Q curve, commonly referred to as hysteresis loops, are used to infer particular mixing patterns. At the South Fork of Brokenback Run (SFBR) in the Shenandoah National Park, Virginia, we have evidence that stream dynamics reflect a system composed of an ephemeral subsurface stormflow zone perched above a perennial water table. The relationship between dissolved silica and stream discharge exhibits hysteresis in the clockwise (CW) direction. Modelling this relationship in the context of three‐component mixing with constant‐concentration end members failed to reproduce the observed c–Q pattern. In this paper we examine the possibility that temporal variation in soil‐water concentrations of silica can explain how CW hysteresis loops in the c–Q curve can arise. In particular, we examine the role of the ratio of a hydrological time scale to a chemical time scale in determining the nature of hysteresis loops. The CW loops that we observe in SFBR can be explained by time variability in soil‐water concentrations only if the chemical (leaching) time constant is less than (or only slightly greater than) the hydrological time constant. The near equality of these time constants is consistent with reports from hydrological measurements and leaching experiments. Copyright © 2001 John Wiley & Sons, Ltd.