The Mitchell Plain, a physiographic unit in south central Indiana, is a classic example of karst topography. Thetown of Orleans, Ind., which is in the Mitchell Plain, is a site of frequent flooding. Factors that enhance the potential for flooding in Orleans may include (1) location of the town in a karst valley, (2) a high runoff-rainfall relation for a loess- and residuum-covered area that drains into an occluded sinkhole near the center of Orleans, and (3) an overtaxed subsurface- drainage system during periods of intense rainfall. The U.S. Geological Survey, in cooperation 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
