Contrasting SWAT predictions of watershed-level streamflow and nutrient loss resulting from static versus dynamic atmospheric CO2 inputs

Authors: Gunn, Kpoti; Veith, Tameria - Tamie; Buda, Anthony

Submitted to: Interagency Conference on Research in the Watersheds
Publication Type: Abstract Only
Publication Acceptance Date: 6/15/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary: No interpretive summary is required for this Abstract. JLB.

Technical Abstract: Past climate observations have indicated a rapid increase in global atmospheric CO2 concentration during late 20th century (13 ppm/decade), and models project further rise throughout the 21st century (24 ppm/decade and 69 ppm/decade in the best and worst case scenario, respectively). We modified SWAT2012, a watershed-level, semi-distributed hydrologic and water quality simulation model, to incorporate dynamic atmospheric CO2 concentrations and account for the mechanistic effects of CO2 concentrations on vegetative transpiration by plant species. Using downscaled predictions from nine climate models for 1960-2100, we investigated the effects of static versus dynamic CO2 inputs on simulated streamflow and nutrient concentrations in an agricultural watershed that drains to the Chesapeake Bay. Preliminary results under current agricultural management indicated that rising CO2 levels through the 1900s were minimal enough to not impact streamflow and water quality, but that additional increases in CO2 will have an impact and must be considered as we move further into the 21st century. In particular, predicted streamflow levels decrease, presumably in response to increased plant evapotranspiration as CO2 concentrations continue to rise. We will compare the predicted streamflow and evapotranspiration between the static and the dynamic CO2 status, and explore the implications of these changes on nutrient concentrations and fluxes.