Alert: Please correct the errors!
Groundwater modeling of a 156,000 hectare basin in IOWA was made possible by intersection of hypsography (contours) and hydrography (river) data layers to determine elevations of the rivers. The elevation of the river is needed as input prescribed heads for the groundwater model. In order to intersect the river and contour data the river and contour data were exported into a GEN file using ArcMAP and a plug-in called ET GeoWizards. The exported files resemble the ArcInfo Generate (GEN) format. A new procedure was devised to intersect the river and contour polylines. The non-trivial logic had been worked out by others at www.faqs.org. The data used for the study is hosted on the IOWA Department of Natural Resources (DNR) Web site (ftp.igsb.uiowa.edu).