Coupled impacts of climate and land use change across a river-lake continuum: Insights from an integrated assessment model of Lake Champlain's Missisquoi Basin, 2000-2040

Asim Zia, University of Vermont
Arne Bomblies, University of Vermont
Andrew W. Schroth, University of Vermont
Christopher Koliba, University of Vermont
Peter D.F. Isles, University of Vermont
Yushiou Tsai, University of Vermont
Ibrahim N. Mohammed, University of Vermont
Gabriela Bucini, University of Vermont
Patrick J. Clemins, University of Vermont
Scott Turnbull, University of Vermont
Morgan Rodgers, University of Vermont
Ahmed Hamed, University of Vermont
Brian Beckage, University of Vermont
Jonathan Winter, Dartmouth College
Carol Adair, University of Vermont
Gillian L. Galford, University of Vermont
Donna Rizzo, University of Vermont
Judith Van Houten, University of Vermont


Global climate change (GCC) is projected to bring higher-intensity precipitation and higher-variability temperature regimes to the Northeastern United States. The interactive effects of GCC with anthropogenic land use and land cover changes (LULCCs) are unknown for watershed level hydrological dynamics and nutrient fluxes to freshwater lakes. Increased nutrient fluxes can promote harmful algal blooms, also exacerbated by warmer water temperatures due to GCC. To address the complex interactions of climate, land and humans, we developed a cascading integrated assessment model to test the impacts of GCC and LULCC on the hydrological regime, water temperature, water quality, bloom duration and severity through 2040 in transnational Lake Champlain's Missisquoi Bay. Temperature and precipitation inputs were statistically downscaled from four global circulation models (GCMs) for three Representative Concentration Pathways. An agent-based model was used to generate four LULCC scenarios. Combined climate and LULCC scenarios drove a distributed hydrological model to estimate river discharge and nutrient input to the lake. Lake nutrient dynamics were simulated with a 3D hydrodynamic-biogeochemical model. We find accelerated GCC could drastically limit land management options to maintain water quality, but the nature and severity of this impact varies dramatically by GCM and GCC scenario.