October 12, 2015 Iowa State University Indrajeet Chaubey Purdue University Water Quality Modeling Food, Energy, Water Workshop

In Situ Input Database Downloadable Site Output Remote Sensing Based Inputs Weather, Vegetation Vigor Soil Moisture Regional Scale Models Regional Scale Models Multiscale Models Field Scale Model 1 Field Scale Model 1 Weather/Climate Weather Simulation Data Weather Data Soil Data Crop Data Databases Field Scale Model 2 Field Scale Model 2 Watershed Scale Models Regional Scale Models

Ditch/ Stream Tile Drains (if applicable) Corn Grass Landscape & Hydrology Precipitation Transpiration (from plants) Plant Uptake Infiltration Percolation Deep Percolation Lateral Flow Return Flow Runoff Evaporation (from leaves and bare soil) Groundwater

Tile Drains (if applicable) Landscape & Nitrogen Corn Grass Precipitation Tillage Fertilizer Trapped by Filter Strip Nitrogen loss with soil erosion Some organic N is attached to eroded soil particles and nitrate (NO 3 - ) is dissolved in water Infiltration (Nitrate) Percolation (Nitrate) Lateral Flow (Nitrate) Deep Percolation (Nitrate Leaching) Runoff Volatilization Plant Uptake

Nutrient Cycling Water Benthic zone SbSb SpSp Sediments SwSw Complete cycle = spiraling length Spiraling length (S) = uptake length (S w ) + turnover length (S b +S p ) (Advection) (Dispersion) (Uptake) (Release)

Water quality modeling– Wildcat Creek Watershed 6 Cibin et al., 2011

7 Perennial bioenergy crops improve water quality Bioenergy crops grown on marginal Lands

8 Perennial bioenergy crops improve ecosystem services Fresh water provision (FWPI), food (FPI) and fuel provision (FuPI), erosion regulation (ERI), and flood regulation (FRI) based on Logsdon & Chaubey, 2013 High slope area: 347 Km 2 (33% of corn/soybean area and 12% of watershed area) St Joseph river watershed

Crop placement optimization - example Objective Functions: maximize biomass production Minimize erosion, nitrate losses Constraints: Grain yield reduction < 10% Total biomass production to support >100 million gallon ethanol At least 20% of biomass from switchgrass Stover removed from slopes < 2%

Effects of climate change on hydrology Projected decrease in snowfall, cover and depth Rainfall is projected to increase Altered streamflow timing and amount – Earlier spring peak flows – Increase in flash floods and high flows – Decline in summer seasonal streamflow Increase risk of summer moisture stress Temperature in projected to increase – Longer growing season – Longer period for growth – Increase evapotranspiration Intense rainfall events – soil erosion – Runoff process

Climate change impacts on ecohydrologic processes 11  Results that are similar under all climate periods and GCMs (error bars) show that water quality benefits due to land use change is generally greater than the effects of climate change variability. Miscanthus in high slope marginal land- St. Joseph River watershed Flow (m 3 /s) Sediment (Mg/ha) Org N (kg/ha) Org P (kg/ha) Nitrate-N (kg/ha) Min P (kg/ha)

Future Research Needs 1.Experimental data at multiple spatial and temporal scales 2.Improvements in the current watershed models to include ecohydrologic process representation 3.Climate change impacts on catchment scale ecohydrologic processes 4.Threshold effects