Impacts of variable agricultural extensification on regional-scale hydrology: the case of the Mississippi River Basin

One of the grand challenges in hydrology is to understand and model the role of land-use changes and their interdependencies with climate from local to global scales. The applications of this kind of research can go from water resources management and extreme events-related risks to land-surface-climate feedbacks. Throughout the previous century the Mississippi River Basin (MRB) experienced variations in climate while the basin's land surface continued to experience anthropogenic alterations. Increasing trends in streamflow and soil moisture have been both observed and simulated in the basin over the course of the century. This research is designed to examine and identify the patterns of hydrologic response in space and time resulting from climate trends and land cover change in the MRB. To achieve this, a macro-scale hydrology model (Variable Infiltration Capacity, VIC) is used with static and dynamic datasets of land cover over a simulation period of 1915-2007. Model results are compared with USGS streamflow gage data. Model simulations include land surface conditions represented with potential vegetation land cover data (static) and annual land cover data representing temporal and spatial changes in the extent of cropland (dynamic). By comparing the model simulations the interdependencies between climate and land cover change on the regional hydrology are estimated. The impacts of major shifts in cropland extent are also explored using observed data and the model simulated land surface fluxes. Results of this study reveal a better understanding of the relationships between land cover, climate, and hydrology in the Mississippi River Basin.