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Event‐based deep drainage and percolation dynamics in Vertosols and Chromosols
Author(s) -
Arnold Sven,
Bulovic Nevenka,
McIntyre Neil,
Finch Warren K.,
Larsen Joshua R.,
Reading Lucy P.,
Baumgartl Thomas
Publication year - 2020
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.13592
Subject(s) - antecedent moisture , drainage , hydrology (agriculture) , percolation (cognitive psychology) , environmental science , soil water , spatial variability , soil science , water content , geology , drainage basin , geography , mathematics , ecology , geotechnical engineering , statistics , runoff curve number , cartography , neuroscience , biology
The quantification of percolation processes and deep drainage rates in cracking clays is challenging due to the existence of multiple flow pathways, including desiccation crack networks, and the effect of variability in antecedent soil moisture and rain event properties. While most previous research on this topic focuses on long‐term average rates, this study focusses on inter‐event dynamics. The study uses data from soil moisture sensors distributed vertically down 4 m profiles of Vertosol and Chromosol soils across 13 sites over an area of approximately 20 km 2 . The objectives were to estimate the temporal and spatial variability of deep drainage rates and to investigate the effect of antecedent soil moisture conditions and rain event properties on deep drainage rates and percolation dynamics. 35 deep drainage events over a 40‐month period contributed 78 % of the total deep drainage of 254 mm at 4 m depth. Average deep drainage estimates were about 15 % (ranging from 0 – 80 % between sites) of total rainfall and irrigation in the Vertosol and 8% (0 – 24 %) in the Chromosol. The event water travel times at 4 m depth were 0.25 – 38 hr and 14 – 39 hr in the Vertosol and Chromosol respectively. The event deep drainage rates averaged across sites were associated with event rainfall volumes (linear regression R 2 = 0.40), with the effect of antecedent conditions evident only when looking at inter‐site differences. The percolation response time was strongly associated with higher rainfall intensities (R 2 = 0.33) with no evidence from the linear regression of an antecedent moisture effect.