Integrated land-surface hydrological and biogeochemical processes in simulating water, energy and carbon fluxes over two different ecosystems

•A coupled hydrological and biogeochemical model (DTVGM-CASACNP) is developed.•Water, energy and carbon fluxes are simulated satisfactorily by the coupled model.•Water and carbon fluxes are sensitive to eco-physiological and runoff parameters.•Water use efficiency of forest ecosystem is higher than that of grass ecosystem.•Coupled model could improve the performances of the simulation than single models.