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Characterizing infiltration and internal drainage of South African dryland soils
Author(s) -
Mavimbela Sabelo S.W.,
Rensburg Leon D.
Publication year - 2016
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.3991
Subject(s) - infiltrometer , drainage , silt , soil water , infiltration (hvac) , hydrology (agriculture) , soil science , bulk density , loam , soil horizon , geology , environmental science , hydraulic conductivity , geomorphology , geotechnical engineering , materials science , ecology , biology , composite material
Abstract Surface infiltration and internal drainage properties of five soil types from arid drylands of South Africa were studied under double ring infiltrometer, rainfall simulation plots (1 m 2 ) and instantaneous drainage plots (9 m 2 ). Changes in soil water content during 40 minute rainfall simulation for a rainstorm with average intensity of 1.61 mm min −1 and 30 day drainage period were measured at various depths by 1.5 m long capacitance soil water measuring (DFM) probe. Different ( P < 0.05) mean surface steady infiltration rate ranged from 0.05 to 4.47 mm min −1 and had a negative power relationship ( R 2 = 0.65) with horizon clay plus fine silt content. Power regression ( R 2 ≥ 86%) described rainstorm infiltration and obtained steady rates within an average time of 15 minutes. Mean total infiltrated soil water content was lowest ( P < 0.05) from surface horizons with either 47.7% clay plus fine silt content or bulk density of 1.91 g cm −3 and exchangeable sodium of not less than 44 mg kg −1 . Surface horizons with lower surface bulk density and total sand fraction of more than 72% had infiltrated depth and mean total infiltrated soil water content up to 40 cm deeper and 0.55 mm mm −1 greater, respectively. Drainage rate at drained upper limit calculated from the Wilcox drainage model ( R 2 ≤ 0.97%) was 0.2 mm day −1 or less were from underlying horizons with either clay plus fine silt of 45% or soft calcium carbonate. Higher drainage rate with accumulative drainage amount greater than 60 mm were from soil profile horizons with clay plus fine silt content of less than 20% and above unity steady infiltration rates. Rainstorm infiltration and drainage rates was shown to depend on permeability and coarseness of the respective soil surface and subsurface horizons; a phenomenon critical for harnessing rain and flood water to recharge groundwater. Copyright © 2016 John Wiley & Sons, Ltd.