Parameterization strategy impacts models' outputs and the associated uncertainty. This is particularly true for transient regional groundwater models where parameters can only be weakly constrained by insufficient observations. However, this is rarely investigated under any particular model structure. This study bridges this gap using a regional groundwater model developed to understand the impact of coal seam gas extraction on groundwater systems in a probabilistic framework. Two different parameterization schemes were implemented for hydraulic conductivity and specific storage. The first method solely relies on the relationship between hydraulic properties and burial depths. The second more complex strategy allows more spatial variations of hydraulic parameters using pilot points. The study provides new insights and practical guidance on the application of groundwater modelling for environmental impact assessment. The results suggest that the choice of model parameterization has a significant influence on predictive uncertainty. The model using the simple parameterization provides predictions with a much wider range than the model with a more sophisticated parameterization. This is because that the lowly parameterized model tends to generate more extreme effective hydraulic parameter fields unless the parameterization simplification converts the inverse problem to a (close to) well-posed problem that rarely exists for applied regional groundwater modelling. The potential impact of model parameterization should be discussed explicitly in groundwater modelling applications to support decision making to avoid misinterpretation of the modelling results.

参数化策略会影响模型的输出以及相关的不确定性。对于瞬态区域地下水模型尤其如此，在该模型中，只能通过观测不足来弱约束参数。但是，很少在任何特定模型结构下对此进行研究。这项研究使用区域地下水模型弥合了这一差距，该模型旨在在概率框架内理解煤层气开采对地下水系统的影响。实施了两种不同的参数化方案，分别用于水力传导率和特定的存储。第一种方法仅依赖于水力特性与埋深之间的关系。第二种更复杂的策略允许使用先导点在更大范围内改变液压参数。该研究为地下水模型在环境影响评估中的应用提供了新的见识和实践指导。结果表明，模型参数化的选择对预测不确定性有重大影响。使用简单参数化的模型所提供的预测范围要比具有更复杂参数化的模型所提供的预测范围大得多。这是因为，除非参数化简化将反问题转换为（接近的）状况良好的问题（对于应用的区域地下水建模而言很少存在），否则参数化程度较低的模型往往会生成更极端的有效水力参数字段。