TY - JOUR
T1 - Unsaturated zone hydrology and cave drip discharge water response
T2 - Implications for speleothem paleoclimate record variability
AU - Markowska, Monika
AU - Baker, Andy
AU - Treble, Pauline C.
AU - Andersen, Martin S.
AU - Hankin, Stuart
AU - Jex, Catherine N.
AU - Tadros, Carol V.
AU - Roach, Regina
N1 - Funding Information:
This study was supported by the National Centre for Groundwater Research and Training as well as the NCRIS Groundwater Infrastructure Initiative . A special thank-you to George Bradford at NSW National Parks and Wildlife Service for continuing to facilitate and support this research at Yarrangobilly Caves. Additional assistance in the field from Katie Coleborn and Tom Cresswell is much appreciated. Silvia Frisia and Andy Spate are also thanked for their helpful discussion and knowledge about the geomorphology and geology of the Yarrangobilly area. Thank-you to Ashley Martin for help with proof reading this manuscript. Lastly, thank-you to the two anonymous reviewers who made valuable comments on this manuscript.
Publisher Copyright:
© 2015.
PY - 2015/10/1
Y1 - 2015/10/1
N2 - High-frequency, spatially-dense discharge monitoring was conducted over fifteen months to characterise unsaturated zone flow at Harrie Wood Cave (HWC), in the Snowy Mountains, Yarrangobilly (SE Australia). The cave was formed in the Late Silurian Yarrangobilly Limestone, a fractured rock associated with very low primary porosity due to past diagenesis. Over our monitoring period we simultaneously measured rainfall, soil moisture saturation and drip discharge rate at fourteen sites to characterise infiltration-discharge relationships. All drip discharge sites exhibited non-Gaussian distributions, indicating long periods where low discharge predominates, punctuated by short infrequent periods of high discharge. However, there was significant variability in discharge between sites and consequently no spatial correlation in the cave. We investigated the depth-discharge relationship at HWC and found a moderate relationship between depth and drip discharge lag (response) times to soil moisture content, but only weak relationships between depth and mean and maximum discharge. This highlights that the karst architecture plays an important role in controlling drip discharge dynamics. Principal Component Analysis (PCA) and Agglomerative Hierarchal Clustering (AHC) were used to classify similar drip types, revealing five unique drip regimes. Two-phase flow and non-linear response to recharge behaviour were observed, suggesting secondary porosity is controlling unsaturated zone flow in mature limestone environments with low primary porosity. Using the data presented here, the first coupled conceptual and box hydrological flow model was developed. This study highlights the heterogeneous nature of hydrological flow in karst and the need to understand unsaturated zone hydrology at the individual drip discharge level, to inform speleothem studies for high-resolution paleoclimate reconstruction.
AB - High-frequency, spatially-dense discharge monitoring was conducted over fifteen months to characterise unsaturated zone flow at Harrie Wood Cave (HWC), in the Snowy Mountains, Yarrangobilly (SE Australia). The cave was formed in the Late Silurian Yarrangobilly Limestone, a fractured rock associated with very low primary porosity due to past diagenesis. Over our monitoring period we simultaneously measured rainfall, soil moisture saturation and drip discharge rate at fourteen sites to characterise infiltration-discharge relationships. All drip discharge sites exhibited non-Gaussian distributions, indicating long periods where low discharge predominates, punctuated by short infrequent periods of high discharge. However, there was significant variability in discharge between sites and consequently no spatial correlation in the cave. We investigated the depth-discharge relationship at HWC and found a moderate relationship between depth and drip discharge lag (response) times to soil moisture content, but only weak relationships between depth and mean and maximum discharge. This highlights that the karst architecture plays an important role in controlling drip discharge dynamics. Principal Component Analysis (PCA) and Agglomerative Hierarchal Clustering (AHC) were used to classify similar drip types, revealing five unique drip regimes. Two-phase flow and non-linear response to recharge behaviour were observed, suggesting secondary porosity is controlling unsaturated zone flow in mature limestone environments with low primary porosity. Using the data presented here, the first coupled conceptual and box hydrological flow model was developed. This study highlights the heterogeneous nature of hydrological flow in karst and the need to understand unsaturated zone hydrology at the individual drip discharge level, to inform speleothem studies for high-resolution paleoclimate reconstruction.
KW - Karst
KW - Speleothem
KW - Unsaturated zone hydrology
KW - Yarrangobilly snowy mountains
UR - http://www.scopus.com/inward/record.url?scp=84940961193&partnerID=8YFLogxK
U2 - 10.1016/j.jhydrol.2014.12.044
DO - 10.1016/j.jhydrol.2014.12.044
M3 - Article
AN - SCOPUS:84940961193
SN - 0022-1694
VL - 529
SP - 662
EP - 675
JO - Journal of Hydrology
JF - Journal of Hydrology
IS - Part 2
ER -