HYDROGEOLOGIC SITE CHARACTERIZATION VIA CROSS SECTION EDITING

摘要

The Arc Hydro Groundwater data model includes a 3D feature class called "GeoSection" for representing 3D cross sections of hydrogeologic units. These features can be constructed by interpolating from rasters representing the tops and bottoms of hydrogeologic units. In many cases, however, it is advantageous to manually construct a cross section by sketching the hydrogeologic units based on analysis of borehole logs and other data. To support this approach, the Arc Hydro Groundwater data model introduces a new set of feature classes for 2D cross section editing in ArcMap. The strategy used with these features involves transforming the z-coordinate of the vertical cross section panels to the y-coordinate of an ArcMap data frame while the x-coordinate represents the distance along the cross section line. A vertical exaggeration can be placed on the z-coordinate, and a coordinate grid can be associated with the data frame that takes the vertical exaggeration into account. The feature classes are built using geoprocessing (GP) tools, and can be edited using the standard ArcMap editing tools. Custom GP tools have also been developed to transform various features onto the local coordinate system of each cross section to aid in the interpretation of the site hydrogeology. This includes borehole logs for adjacent wells, lines from rasters, and lines representing the intersection with surficial geology maps. Completed 2D cross sections can be transformed to 3D multipatches and vice versa. These feature classes and tools are illustrated using data from a recent case study in the Sacramento California region.