This research includes analyzing the impacts of wildfires on the global terrestrial biosphere carbon cycle, assessing the patterns of biome carbon fluxes in response to droughts at different time scales, and estimating carbon fluxes with Terrestrial Ecosystem Model. This includes modeling the lateral dissolved organic carbon (DOC) flux into an earth system model. The lateral DOC flux from soils to inland waters is a fundamental component of the global carbon cycle; however, considerable debate has been proposed as to how climate change and anthropogenic actives alter the spatio-temporal patterns and potential fates of DOC flux. To access the delivery process and potential fates of DOC flux, a process-based terrestrial-aquatic DOC fluxes model was developed (TAF-DOC), which has the ability to estimate the spatial and temporal dynamics of DOC flux through incorporating various environmental factors (e.g., sulfur and nitrogen deposition, land cover and landscape) that have not been completely included or well represented in existing modeling frameworks. The TAF-DOC model is used to estimate DOC flux and potential fates in the conterminous United States.