Directions of ground-water flow and locations of ground-water divides in the Lost River Watershed near Orleans, Indiana

The U.S. Geological Survey, in cooperations with the U.S. Army Corps of Engineers, conducted a study during October 1993-April 1994 to improve an understanding of the hydrology of the Lost River watershed near Orleans, Ind. Elements of the study included: (1) constructing a map of the composite ground-water potentiometric-surface of the study area, (2) injecting and recovering fluorescent dyes at karst features in the study area to help locate ground-water-flow paths and drainage divides, (3) compiling a bibliography of references describing the study area, and (4) constructing a map of karst features. The composite ground- water-potentiometric surface map and the eight dye traces done as part of this study indicate the approximate locations of the subsurface drainage divides near Orleans. Subsurface drainage near Orleans flows primarily southwest to a reemergence at Orangeville Rise, Orangeville, Ind. Dye clouds injected north of the Orangeville Rise drainage basin reemerged in the Hamer Cave outlet stream, Spring Mill State Park, Ind. The drainage divide that separates subsurface flow to Orangeville Rise from flow to Hamer Cave does not coincide with the surface-water drainage divide. Several factors may contribute to the flooding in Orleans, including: (1) an overtaxed storm sewer system, (2) location of the town in a karst valley, (3) a high runoff- rainfall relation for a 1oess- and residuum-covered area that drains into an occluded sinkhole near the center of Orleans, and (4) an overtaxed subsurface drainage system during periods of intense rainfall.