Assessing Impacts of Climate and Land Use Change on Terrestrial-Ocean Fluxes of Carbon and Nutrients and Their Cycling in Coastal Ecosystems

Sponsor:  National Aeronautics and Space Administration


University of Southern Mississippi: Steve Lohrenz

Funding period

July 2010 – June 2013


Changing climate and land use practices have the potential to dramatically alter coupled hydrologic-biogeochemical processes and associated movement of water, carbon and nutrients through various terrestrial reservoirs. Such changes will ultimately influence the delivery of dissolved and particulate materials from terrestrial systems into rivers, estuaries, and coastal ocean waters. Consequences of climate and land use related changes will be particularly evident in large river basins and their associated coastal outflow regions. The large spatial extent of such systems necessitates a combination of macro-scale satellite observations and model-based approaches coupled with targeted ground-based site studies to adequately characterize relationships among climate forcing (e.g., wind and precipitation patterns, temperature, solar radiation, humidity, extreme weather events), land use/land cover and land practices, and transport of materials through watersheds and, ultimately, to coastal regions. An integrated suite of models will be used in conjunction with remotely sensed observations with the objectives of describing processes controlling fluxes on land, their coupling to riverine systems, and the delivery of materials to estuaries and the coastal ocean. Terrestrial ecosystem models coupled with physical-biogeochemical coastal and estuarine models will be used in conjunction with satellite observations to examine water quality, transport, and ecosystem function resulting from climate and land use change.

Our objectives are:

  1. Assemble and evaluate long term datasets for the assessment of impacts of climate variability, extreme weather events, and land use practices on transport of carbon and nutrients within terrestrial systems and the delivery of materials to waterways and rivers
  2. Using the Mississippi River as a testbed, develop and evaluate an integrated suite of models to describe and predict linkages between terrestrial and riverine systems, transport of carbon and nutrients in the Mississippi river and its tributaries, and associated cycling of carbon and nutrients in coastal ocean waters
  3. Evaluate uncertainty in model products and identify areas where improved model performance is needed through model refinement and data assimilation

The integrated suite of models will be developed with three functionalities in mind: a) Process-level descriptions of major mechanisms influencing carbon and nutrient transport within terrestrial systems through watersheds to coastal waters, and the subsequent impacts on water quality and carbon and nutrient cycling; b) Predictive capabilities enabling an examination of impacts of climate variability, climate change, and land use change on terrestrial-ocean fluxes and coastal ecosystem responses; c) Portability that allows the resulting model toolkit to be easily applied to other large, river influenced systems such as the Changjiang River Basin and East China Sea. The proposed research will employ remotely-sensed observations to both initiate and validate models and provide supporting observations for the interpretation of model products. The work would address the goals of the solicitation through integrating hydrological and ecological models to better describe and understand the connectivity of upland and coastal marine systems and the manner in which climate, weather and human activities influence processes within the connecting watershed. The proposed region of study provides an excellent setting to carry out this work as there are a large number of supporting datasets and on-going programs that will complement this work. The proposed work is also closely aligned with objectives of the North American Carbon Program and will contribute to efforts to refine continental carbon budgets. Results of this work will also benefit efforts describe and predict how land use and land cover changes impact coastal water quality including possible effects of coastal eutrophication and hypoxia. Finally, the modeling and observational approaches developed for this work will have applicability to other large river watershed-coastal systems.