A Richards-based soil water model was implemented in the APEX and EPIC terrestrial ecosystem models to improve their hydrologic modeling capabilities. The Richards model together with two existing soil water models were calibrated and evaluated to assess their performance for simulating watershed-level hydrology under scenarios of landscape conversion to bioenergy crop production. The Richards model was shown to better reflect observed soil-water dynamics in grain (corn) and cellulosic (switchgrass) bioenergy agroecosystems, whereas all three models simulated historic streamflows comparably. Application of the models to understand the impacts of widespread landscape conversion from traditional agriculture to bioenergy producing landscapes indicated disparate conclusions, with the Richards-based simulations indicating a modest 1.0% reduction in streamflow whereas the existing models simulated sizable reductions of 10.6–16.1%. This study clearly demonstrates the impact of model methodology on system understanding and contextualizes the wide range of simulated streamflow impacts from bioenergy conversions reported in the literature.

在 APEX 和 EPIC 陆地生态系统模型中实施了基于理查兹的土壤水模型，以提高其水文建模能力。理查兹模型与两个现有的土壤水模型一起被校准和评估，以评估它们在景观转换为生物能源作物生产的情景下模拟流域级水文的性能。理查兹模型被证明可以更好地反映在谷物（玉米）和纤维素（柳枝稷）生物能源农业生态系统中观察到的土壤-水动力学，而所有三个模型都模拟了历史流量。应用模型来了解从传统农业到生物能源生产景观的广泛景观转换的影响表明了不同的结论，基于理查兹的模拟表明适度的 1。流量减少 0%，而现有模型模拟了 10.6-16.1% 的大幅减少。这项研究清楚地证明了模型方法对系统理解的影响，并将文献中报道的生物能源转换的广泛模拟流影响背景化。