A Simple Modelling Framework for Shallow Subsurface Water Storage and Flow

TY - JOUR

T1 - A Simple Modelling Framework for Shallow Subsurface Water Storage and Flow

AU - Verrot, Lucile

AU - Geris, Josie

AU - Gao, L

AU - Peng, X

AU - Oyesiku-Blakemore, Joe

AU - Smith, Jo

AU - Hodson, Mark Edward

AU - Zhang, Ganlin

AU - Hallett, Paul

N1 - ©2019 by the authors.

PY - 2019/8/19

Y1 - 2019/8/19

N2 - Water storage and flow in shallow subsurface drives runoff generation, vegetation water use and nutrient cycling. Modelling these processes under non-steady state conditions is challenging, particularly in regions like the subtropics that experience extreme wet and dry periods. At the catchment-scale, physically-based equations (e.g., Richards equation) are impractical due to their complexity, while conceptual models typically rely on steady state assumptions not found in daily hydrological dynamics. We addressed this by developing a simple modelling framework for shallow subsurface water dynamics based on physical relationships and a proxy parameter for the fluxes induced by non-unit hydraulic gradients. We demonstrate its applicability for six generic soil textures and for an Acrisol in subtropical China. Results showed that our new approach represents top soil daily fluxes and storage better than, and as fast as, standard conceptual approaches. Moreover, it was less complex and up to two orders of magnitude faster than simulating Richards equation, making it easy to include in existing hydrological models.

AB - Water storage and flow in shallow subsurface drives runoff generation, vegetation water use and nutrient cycling. Modelling these processes under non-steady state conditions is challenging, particularly in regions like the subtropics that experience extreme wet and dry periods. At the catchment-scale, physically-based equations (e.g., Richards equation) are impractical due to their complexity, while conceptual models typically rely on steady state assumptions not found in daily hydrological dynamics. We addressed this by developing a simple modelling framework for shallow subsurface water dynamics based on physical relationships and a proxy parameter for the fluxes induced by non-unit hydraulic gradients. We demonstrate its applicability for six generic soil textures and for an Acrisol in subtropical China. Results showed that our new approach represents top soil daily fluxes and storage better than, and as fast as, standard conceptual approaches. Moreover, it was less complex and up to two orders of magnitude faster than simulating Richards equation, making it easy to include in existing hydrological models.

KW - hydrological modelling

KW - soil water content

KW - soil water fluxes

KW - vadose zone

KW - non-unit hydraulic gradient

KW - transient state

U2 - 10.3390/w11081725

DO - 10.3390/w11081725

M3 - Article

SN - 2073-4441

VL - 11

JO - Water

JF - Water

IS - 8

M1 - 1725

ER -