Development of an analytic element ground water model of the Netherlands.

In 1985, I attended the first course on analytic ele-ment modeling in the Netherlands, where Professor OttoStrack of the University of Minnesota presented hisnewly conceived analytic element method (AEM; Strack1989) at the Technical University Delft from which hegraduated years before. While he explained the principlesand applications of the method, I started to realize thatthe AEM might be uniquely suited to modeling detailedground water flow systems covering large regions be-cause it enables cutting, pasting, and linking of entiremodels as well as of model parts.In 1987, at the National Institute for Inland Water Man-agement and Waste Water Treatment in the Netherlands(RIZA),therewasmuchinterestinnationalmodelingintheNetherlands because of serious water management prob-lems that first became apparent during the major drought of1976. In fact, there existed a national water managementsystem of models, called PAWN (Policy Analysis for Watermanagement in the Netherlands; Rand Corporation 1982).PAWN is an integrated system of models for simulating thedistribution over the numerous national and regional sur-face waters in this wet country and the effects on agricul-ture, nature (ecology), power plants, shipping, flushing ofcoastal areas against salt water intrusion, and drinkingwater. PAWN was lacking treatment of the ground waterreservoir, which had become apparent in the policy analy-sis of 1985 (Pulles 1985). The NAtional GROundwaterModel (NAGROM) should cover this gap as part ofPAWN.