FULLY DYNAMIC GROUNDWATER REPRESENTATION IN THE MATSIRO LAND SURFACE MODEL

Despite significant development of land Surface models (LSMs) over recent years, the representation of near surface hydrological processes is still problematic. In particular, the lower boundary condition of the soil model is often assumed as ‘a free (gravity) drainage’ or ‘a zero moisture flux’ largely neglecting the interaction between groundwater (GW) reservoir and land surface hydrological fluxes. GW affects the prediction of soil moisture and subsequently land-surface hydrological fluxes and regional climate. This study investigates the effect of integrating a GW representation into a LSM, Minimal Advanced Treatments of Surface Integration and RunOff (MATSIRO). The MATSIRO-GW model has enhanced the partitioning of runoff, as well as saturated-unsaturated zone soil moisture. The total runoff and water table depth simulations have been significantly improved. Evapotranspiration in the dry season has been enhanced due to increase in soil moisture resulting from upward capillary flux from GW reservoir.

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