Assessing long-term hydrologic impact of climate change using an ensemble approach and comparison with Global Gridded Model-A case study on Goodwater Creek Experimental Watershed

Authors: GAUTAM, SAGAR - University Of Missouri; COSTELLO, CHRISTINE - University Of Missouri; Baffaut, Claire; THOMPSON, ALLEN - University Of Missouri; SVOMA, BOHUMIL - University Of Missouri; PHUNG, QUANG - University Of Missouri; Sadler, Edward

Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/24/2018
Publication Date: 4/26/2018
Citation: Gautam, S., Costello, C., Baffaut, C., Thompson, A., Svoma, B.M., Phung, Q.A., Sadler, E.J. 2018. Assessing long-term hydrologic impact of climate change using an ensemble approach and comparison with Global Gridded Model-A case study on Goodwater Creek Experimental Watershed. Water. 10(5):564. doi:10.3390/w10050564.
DOI: https://doi.org/10.3390/w10050564

Interpretive Summary: Future projections of temperature and precipitation were used to simulate future stream flow, surface runoff, and transpiration from plants in the Goodwater Creek Experimental Watershed (GCEW), located in Boone and Audrain counties in Missouri. The climate data were obtained from multiple climate datasets and used to drive a computer simulation model (the Soil and Water Assessment Tool) to simulate the above variables. Results indicated increased springtime precipitation, total flow, surface runoff and a shift in evapotranspiration peak one month earlier in the future. Results obtained with global gridded models that use soil and land use input data at a coarser resolution than SWAT and have different mathematical representation of physical processes showed lower monthly peak runoff and greater low runoff values compared to SWAT. Results show the benefits of impact assessments at small scales with heterogeneous sets of parameters to adequately represent extreme conditions that are muted in global gridded model studies by spatial averaging over large study domains. Understanding the potential for future changes in temperature, precipitation, stream flow and thus water availability for people and agriculture are important for watershed managers and farmers. This information allows for adequate planning for water deficits and excesses for municipal and agricultural water demand.

Technical Abstract: Potential impacts of climate change on hydrologic components of Goodwater Creek Experimental Watershed were assessed using climate datasets from the Coupled Model Intercomparison Project Phase 5 and Soil and Water Assessment Tool (SWAT). Historical and future ensembles of downscaled precipitation and temperature, and modeled water yield, surface runoff and evapotranspiration were compared. Ensemble SWAT results indicate increased springtime precipitation, water yield, surface runoff and a shift in evapotranspiration peak one month earlier in the future. To evaluate the performance of model spatial resolution, gridded surface runoff estimated by Lund–Potsdam–Jena managed Land (LPJmL) and Jena Diversity-Dynamic Global Vegetation model (JeDi-DGVM) were compared to SWAT. Long-term comparison shows 6-8% higher average annual runoff prediction for LPJmL and 5-30% lower prediction for JeDi-DGVM compared to SWAT. Although annual runoff showed little change for LPJmL, monthly runoff projection under predicted peak runoff and over predicted low runoff for LPJmL compared to SWAT. The reasons for these differences include difference in spatial resolution of model inputs and mathematical representation of physical processes. Results indicate benefits of impact assessments at small scales with heterogeneous sets of parameters to adequately represent extreme conditions that are muted in global gridded model studies by spatial averaging over large study domains.