On the importance of hysteresis and heterogeneity in the numerical simulation of unsaturated flow

Kei Nakagawa, Masahiko Saito, Ronny Berndtsson
Released: June 01, 2012

On the importance of hysteresis and heterogeneity in the numerical simulation of unsaturated flow
Kei Nakagawa1), Masahiko Saito2), Ronny Berndtsson3)

1) Graduate School of Fisheries Science and Environmental Studies, Nagasaki University
2) Organization of Advanced Science and Technology, Kobe University
3) Department of Water Resources Engineering and Center for Middle Eastern Studies, Lund University

Released 2012/06/01

Soil hydraulic properties in field scale porous media are distributed with large spatial heterogeneity. Thus, detailed understanding of micro-physical properties leading to macro-scale heterogeneity is important for generalizing purposes in modeling. Hysteretic water retention properties greatly affect solute transport under unsaturated condition. In this study, laboratory infiltration experiments were carried out to investigate the importance of hysteresis in numerical modeling of water flow under heterogeneous distribution of hydraulic conductivity. Soil water content was observed by time domain reflectometry using small printed circuit board probes (PCBP). The PCBP observations were compared to results from numerical simulations involving saturated-unsaturated seepage analysis and two-phase flow with/without hysteresis effects. Observations were compared to both uniform and heterogeneous parameter modeling. Differences between unsaturated-saturated and two-phase flow were quite small in the numerical results for soil water content. The uniform parameter model, however, could not properly reproduce experimental water content change. The numerical results of water content change including hysteresis matched better observations for the unsaturated-saturated and two-phase flow cases. Results displayed that it is important to take heterogeneity and hysteresis into consideration in the numerical modeling in both two-phase and saturated-unsaturated flow analysis.

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Edited and published by : Japan Society of Hydrology and Water Resources Produced and listed by : Nakanishi Printing Co.,Ltd.(Vol. 4 (2010)) Gakujutsu-tosho Printing Co. Ltd.(Vol. 2 (2008) – Vol. 4 (2010))

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