GroMoPo Metadata for Netherlands analytic element model

In 1985, I attended the first course on analytic element modeling in the Netherlands, where Professor Otto Strack of the University of Minnesota presented his newly conceived analytic element method (AEM; Strack 1989) at the Technical University Delft from which he graduated years before. While he explained the principles and applications of the method, I started to realize that the AEM might be uniquely suited to modeling detailed ground water flow systems covering large regions because it enables cutting, pasting, and linking of entire models as well as of model parts. In 1987, at the National Institute for Inland Water Management and Waste Water Treatment in the Netherlands (RIZA), there was much interest in national modeling in the Netherlands because of serious water management problems that first became apparent during the major drought of 1976. In fact, there existed a national water management system of models, called PAWN (Policy Analysis for Water management in the Netherlands; Rand Corporation 1982). PAWN is an integrated system of models for simulating the distribution over the numerous national and regional surface waters in this wet country and the effects on agriculture, nature (ecology), power plants, shipping, flushing of coastal areas against salt water intrusion, and drinking water. PAWN was lacking treatment of the ground water reservoir, which had become apparent in the policy analysis of 1985 (Pulles 1985). The NAtional GROundwater Model (NAGROM) should cover this gap as part of PAWN.

1985年，我在荷兰修读了首届解析元建模课程，明尼苏达大学的奥托·斯特拉克（Otto Strack）教授于代尔夫特理工大学——他的母校——分享了其全新提出的解析元方法（analytic element method, AEM; Strack 1989）。在他讲解该方法的原理与应用场景时，我逐渐意识到，解析元方法或许独具适配性，可用于模拟覆盖大范围区域的精细地下水流系统：该方法支持对完整模型乃至模型部件进行剪切、粘贴与链接操作。

1987年，在荷兰国家内陆水管理与废水处理研究所（RIZA），当时荷兰国内对国家级水文建模的研究热情高涨，这源于1976年大旱灾期间首次凸显的严峻水管理问题。事实上，彼时已存在一套名为PAWN（荷兰水管理政策分析，Policy Analysis for Water management in the Netherlands; 兰德公司1982）的国家级集成模型系统。PAWN可用于模拟这个多雨国家众多国家级与区域级地表水体的空间分布，以及该分布对农业、自然（生态）、发电厂、航运、抵御海水入侵的海岸冲淤与饮用水供应的影响。

PAWN系统未涵盖地下水储层的模拟环节，这一缺陷在1985年的政策分析中已显露无遗（Pulles 1985）。国家地下水模型（National GROundwater Model, NAGROM）正是为填补这一空白而开发，作为PAWN系统的配套组成部分。