CropSyst regional parameterization and calibration over Columbia River Basin

Primary author: Fabio Scarpare
Co-author(s): Claudio Stockle; Roger Nelson; Kirti Rajagopalan; Mingliang Liu; Jennifer Adam
Faculty sponsor: Jennifer Adam

Primary college/unit: Voiland College of Engineering and Architecture
Campus: Pullman


Crop water demand is key for policy and resource decision-making questions, including the processing of new irrigation water rights, examining water availability for both out-of-stream and instream uses. Conventional model calibration methods, which concentrate on a model’s performance at plot scale, cannot be used for large-scale regional simulation. Therefore, this study aims to describe a low-data approach used for developing detailed crop parameterization data required for regional level application. CropSyst was parameterized and calibrated based on its sensitivity analysis for the main agricultural irrigated lands in the Columbia River Basin; for most of Oregon, eastern Washington, southern Idaho, and western Montana States. Twenty-five crop types among cereal, forage, fruits and vegetables were selected by using the USDA Crop Data Layer 2018 in each sub-region. Thirty-six years of daily meteorological variables were used to drive the simulations. The calibration was performed by first adjusting the growing season (defined as planting to maturity). Next, the phenological development stages between planting and maturity (end of vegetative growth, flowering, beginning of yield formation, senescence and full senescence if reached) with the green canopy cover development were adjusted. Yield calibration was the last step performed, which was based on model`s sensitivity analysis. Scientific papers and irrigation field trials performed by several Research Extension Centers with less than ten years old developed in the same region were used as main sources for model evaluation. The simulation results were satisfactory and similar to those observed in the literature data, which enable its use across the Pacific Northwest.