For Simulation of Hydrologic and Water Quality Processes in Irrigated Agricultural Watersheds By Tyler Wible, Jeff Ditty, Dr. Ryan Bailey, Dr. Mazdak Arabi Civil and Environmental Engineering Colorado State University Fort Collins, CO, USA
Introduce models Describe study watershed Outline model integration Present future application
SWAT (Arnold et al., 1998) Basin scale, continuous time watershed model Analyzes impacts on water, sediment, and chemical yields within basin, land use, climate change, scenario analysis MODFLOW-NWT (Niswonger et al., 2011) Groundwater Flow Model for saturated subsurface flow Finite-difference, grid-based Fully distributed aquifer properties UZF-RT3D (Bailey et al., 2012) Variably saturated porous media solute reactive transport model Based on original RT3D (Clement 1997)
Upper Klamath River Basin Heavily influenced by agriculture Abundant natural springs Groundwater driven system Concerns about future water quantity and quality
Wood River Headwaters Photo courtesy of Rosemary Records
Sycan River (surface runoff driven) R 2 0.7552 Nash-Sutcliffe 0.5658
North Fork of Sprague River (groundwater driven) R 2 0.7584 Nash-Sutcliffe 0.2732
Surface Watershed models Lack detail for: Spatially variable aquifer parameters Significant baseflow contribution to stream flow Finite-Difference Groundwater models Lack surface processes Agricultural influence Riparian zones Best Management Practices (BMPs) impacts
Use popular, documented, open source surface water and groundwater models Retain the respective strengths of models Remove groundwater computations from surface watershed model Use surface model to assess various climate change scenarios and BMPs
Model Integration Evapotranspiration Plant Growth Volatilization canal Root Zone Processes Uptake SWAT Stream stage Solute transport Bedrock Breakdown of watershed processes simulated by SWAT SWAT Infiltration Evaporation Plant growth, root zone processes Overland flow and transport Lateral subsurface flow in soil zone Stream flow and transport
Model Integration Vadose Zone Percolation Water Table Upflux Seepage Pumping Well MODFLOW-NWT-UZF Groundwater discharge Groundwater flow Breakdown of watershed processes simulated by MODFLOW-NWT Bedrock MODFLOW-NWT Vadose Zone percolation (UZF1 package) Water table elevation Saturated groundwater flow Groundwater pumping Baseflow/stream seepage (RIV package)
Model Integration Transport N Transport N, P transport N, P Concentration UZF-RT3D N, P mass loading N, P reactive transport Breakdown of watershed processes simulated by UZF-RT3D UZF-RT3D Autotrophic Denitrification Bedrock Variably saturated porous media chemical transport Chemical interaction with geology Pumped groundwater chemical fluxes Mass loadings of N, P to/from stream
Run SWAT Map SWAT outputs to MODFLOW and UZF- RT3D Run MODFLOW Map MODFLOW outputs to UZF-RT3D and SWAT Run UZF-RT3D Map UZD-RT3D outputs to SWAT
South Platte River Basin Extensive Irrigation Large Population Lower Arkansas River Valley Extensive Irrigation Inter-state minimum flow requirement
Acknowledgments Rosemary Records (Pictures and Sprague River SWAT Results) This study is funded by the U.S. Department of Agriculture-National Institute of Food and Agriculture (NIFA) Grant Number 2012-67003-19904. References Arnold, J.G., Srinivasan, R., Muttiah, R.S., Williams, J.R. 1998. Large area hydrologic modeling and assessment Part I Model development. Journal of American Water Resources Association. (JAWRA), 34(1): 73-89. Bailey, R.T., Morway, E.D., Niswonger, R.G., and T.K. Gates. 2012. Modeling variably-saturated multispecies reactive transport with MODFLOW-UZF and RT3D. Groundwater, doi: 10.1111/j.1745-6584.2012.01009.x. Clement, T.P. 1997. RT3D A modular computer code for simulating reactive multi-species transport in 3-dimensional groundwater aquifer. Draft report. PNNL-SA-28967. Richland, Washington: PNNL. Niswonger, R.G., Panday, S., and M. Ibaraki. 2011. MODFLOW-NWT, A Newton formulation for MODFLOW-2005: USGS Survey Techniques and Methods 6 A37.