Evaluating Hydrological Output of DRAINMOD from Measured and Estimated Soil Properties Advisor: Dr. Christopher Hay Presenter: Govinda Karki Graduate Research Assistant Agricultural and Biosystems Engineering July 29, 2015

Introduction  DRAINMOD Requires soil properties input: Saturated hydraulic conductivity (Ks) Soil water characteristics curve (SWCC) Drainage Volume Upward flux Green-Ampt Parameters  Input for DRAINMOD : Soil Properties (SWCC and Ksat) determined by:  Direct Method (Field Methods)  Indirect Method ( Pedotransfer Functions, PTFs :Rosetta) Derived from SWCC

Introduction  Direct Method:  Hyprop (Wind and Schindler evaporation method) and WP4C (dew point potentiometer) instruments (Peters and Durner 2008).  Indirect Method:  Widely used PTF is Rosetta (Schaap et al. 2001) and uses five different levels of input:  H1: USDA textural class  H2: H1 plus % of sand silt and clay  H3: H2 plus dry bulk density  H4: H3 plus water content at suction -33kPa (field capacity)  H5: H4 plus water content at -1500kPa (wilting point)  DRAINMOD has inbuilt utilities to convert soil properties in formatted input file using Rosetta Hyprop WP4C

Objectives  To determine soil properties (Ksat and SWCC) using pedotransfer function (Rosetta), and Hyprop and WP4C  Compare DRAINMOD hydrological output of direct measurement (hyprop & WP4C) and Rosetta inputs with Calibrated values

Materials & Methods Study Area  Location: Located at SERF (Beresford, Clay Co., SD)  Soil Type: Trent Series (EhA), Silty clay loam  Climate ( ): Average annual precipitation : 642 mm Average daily maximum Temp: 14.7 ºC Average daily minimum Temp: 1.8 ºC  Field plots acre (5.75ha) 6-plots half of the plots were drained and rest was undrained

Materials & Methods Soil Information:  USDA, NRCS (SSURGO) soil database used in Rosetta for SWCC  Soil water characteristics curve was generated using Hyprop-DES Measured SWCC Water Content(θ)Head(h) Saturated Hydraulic Conductivity (K sat,cm/hr.) DepthValue of K sat Measured and Rosetta derived soil parameters for DRAINMOD input Rosetta derived SWCC Water Content(θ)Head(h) Saturated Hydraulic Conductivity (K sat,cm/hr.) DepthValue of K sat

Materials & Methods Model Simulation: DRAINMOD simulation for using measured weather data and soil hydraulic properties (calibration of model) Long-term simulation ( ) conducted for hydrological output Simulation conducted using Rosetta (Ro) Simulation conducted using Direct Measurement (Mo) [ SWCC, Ksat from hyprop-DES] Soil temperature (Freezing and Thawing) was considered for simulation Statistical Analysis: Nash-Sutcliffe efficiency (E): Normalized root mean square (RMSE): Mean absolute error (MAE):

Results Comparison of Average Annual Drainage and Annual Runoff Average annual DrainageAverage annual Runoff Co- Calibrated ValuesMo- Direct Measured valuesRo- Rosetta values

Results Comparison of Calibrated with Simulated Drainage flow (Nash-Sutcliffe and R2) – Yearly Values

Results Comparison of Calibrated with Simulated Drainage flow (Nash-Sutcliffe and R2) – Monlthy Values

Results Comparison of Calibrated with Simulated Drainage flow (Nash-Sutcliffe and R2) – Daily Values

Results Comparison of Calibrated with Simulated Runoff flow (Nash-Sutcliffe and R2) – Yearly Values

Results Comparison of Calibrated with Simulated Runoff flow (Nash-Sutcliffe and R2) – Monthly Values

Results Comparison of Calibrated with Simulated Runoff flow (Nash-Sutcliffe and R2) – Daily Values

Results Statistical comparison between Mo and Ro for Drainage and Runoff Soil Input YearlyMonthlyDaily DrainageRunoffDrainageRunoffDrainageRunoff E RMSE(cm) MAE(cm) E RMSE(cm) MAE(cm) E RMSE(cm) MAE(cm) E RMSE(cm) MAE(cm) E RMSE(cm) MAE(cm) E RMSE(cm) MAE(cm) Ro Mo E- Nash-Sutcliffe efficiency RMSE- Root Mean Squared ErrorMAE- Mean Absolute Error

Summary DRAINMOD Output obtained using SWCC from Hyprop & WP4C and Ksat from Hyprop-DES gives fairly close result compared to calibrated values DRAINMOD output obtained from hyprop& WP4C (for SWCC) and Hyprop-DES (for K sat ) fits better than Rosetta Rosetta-derived soil input can be used in DRAINMOD for long-term simulation Statistical measure of average drainage output fits better than average runoff

Acknowledgements East Dakota Water Development District South Dakota Corn Utilization Council South Dakota Ag Experiment Station With additional in-kind support provided by Agri Drain Corp. and ADS, Inc.

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