Results from version 3.1 of the 4km-resolution biogeochemistry and sediments model of the Great Barrier Reef (GBR4), forced by version 2.0 of the 4km-resolution hydrodynamic model and by a baseline catchment scenario which is derived from P2R SOURCE Catchments with 2019 catchment condition from December 1, 2010 to June 30, 2018 and from empirical SOURCE Catchments with 2019 catchment condition from July 1, 2018 to April 30, 2019. This model configuration and associated results dataset may be referred to as "GBR4_H2p0_B3p1_Cq3b_Dhnd" according to the eReefs biogeochemical simulation naming protocol. The model ran in hindcast-mode as one of a suite of simulations which included pre-industrial (GBR4_H2p0_B3p1_Cq3p_Dhnd) and reduced-load (GBR4_H2p0_B3p1_Cq3R_Dhnd) catchment scenarios.