A multimethod approach to inform epikarst drip discharge modelling: Implications for palaeo-climate reconstruction
A multimethod approach to inform epikarst drip discharge modelling: Implications for palaeo-climate reconstruction
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DOI：
10.1002/hyp.11392
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发表时间：
2017-12-30
影响因子：
3.2
通讯作者：
McGowan, Hamish
中科院分区：
文献类型：
--
作者：
Campbell, Micheline;Callow, John Nikolaus;McGowan, Hamish
解决形成洞穴沉积物的水文过程及其所包含的古气候档案是困难的。典型的水文调查方法不适合喀斯特地貌，水文物理学很少应用，滴水监测和建模有局限性，忽视潜在的水文影响可能导致代理记录不能反映外部环境。我们的目标是了解的过程和控制，创造了一个洞穴（JC 001）保存在洞穴的奇异，泽西洞穴的一部分，在Yjobilly洞穴，澳大利亚，推断可能的性质和分辨率的记录的古气候代理记录。电阻率层析成像（ERT），传统的测量和滴水流量监测（2013年4月至2015年2月）被用来调查的结构和水文的表层岩溶覆盖的古怪的石窟。通过这些方法收集的数据，然后用来构建一个物理上知情的和简约的滴灌水文模型。地球物理学表明，在山坡上的变化以上的洞穴的古怪搭配与低电阻率的区域，形成一个表岩溶水库作用，以提供增强放电的洞穴。滴水监测表现出滞后行为与一个独特的阈值响应，和一个简单的滴水分类表明，洞穴沉积物与滴水有可能记录古季节性或年度-十年信号。排放模型表明，排放包括快速和缓慢的流动，排放可能是常年。这些多方法的结果一起表明，洞穴可能代表了一个古气候记录的长度和分辨率前所未有的非冰川地区的南半球和澳大利亚，特别是将显着提高目前的知识的气候澳大利亚东南部。虽然ERT方法以前已被应用于岩溶景观，据我们所知，这是第一次应用这些多种方法相结合的方法来评估的洞穴沉积物的保真度，基于对水文过程的了解，古气候重建。
Resolving the hydrological processes that form speleothems and the palaeo-climate archives that they contain is difficult. Typical approaches to hydrological investigation are not suited to karst landscapes, geophysics are seldom applied, drip monitoring and modelling have limitations, and ignoring potential hydrological impacts can result in a proxy record that does not reflect the external environment. We aim to understand the processes and controls that have created a palaeo-climate proxy record preserved in a speleothem (JC001) in the Grotto of Oddities, part of the Jersey Cave at the Yarrangobilly Caves, Australia, to infer the likely nature and resolution of this record. Electrical resistivity tomography (ERT), traditional surveying, and drip discharge monitoring (April 2013 to February 2015) were used to investigate the structure and hydrology of the epikarst overlying the Grotto of Oddities. Data collected through these methods were then used to construct a physically informed and parsimonious drip hydrology model. Geophysics showed that changes in hillslope above the Grotto of Oddities are collocated with a region of low resistivity, which forms an epikarstic reservoir acting to supply enhanced discharge to the speleothem. Drip monitoring showed hysteretic behaviour with a distinct threshold response, and a simple drip classification indicated that the speleothem associated with the drip has the potential to record palaeo-seasonality or an annual-decadal signal. Discharge modelling indicated discharge was comprised of quick and slow flow, and that discharge is probably perennial. These multimethod results together indicate that the speleothem likely represents a palaeo-climate record of a length and resolution unprecedented for nonglacial areas of the Southern Hemisphere and for Australia in particular and will significantly enhance current knowledge of the climate of southeast Australia. Although ERT methods have previously been applied in the karst landscape, to our knowledge, this represents the first application of these multiple methods in combination as an approach to assess the fidelity of a speleothem, based on an understanding of the hydrological processes for palaeo-climate reconstruction.