Description of the physical environment and coal-mining history of west-central Indiana, with emphasis on six small watersheds

Abstract

This report describes the physical and human environment and coal-mining history of west-central Indiana, with emphasis on six small watersheds selected for study of the hydrologic effects of surface coal mining. The report summarizes information on the geology, geomorphology, soils, climate, hydrology, water use, land use, population, and coal-mining history of Clay, Owen, Sullivan, and Vigo Counties in Indiana. Site-specific information is given on the morphology, geology, soils, land use, coal-mining history, and hydrologic instrumentation of the six watersheds, which are each less than 3 square miles in area. West-central Indiana is underlain by coal-bearing Pennsylvanian rocks. Nearly all of the area has been glaciated at least once and is characterized by wide flood plains and broad, flat uplands. Most of the soils have formed in loess or in loess overlying Illinoian till. The Wabash, White, and Eel Rivers are the major drainages in west-central Indiana. Average annual precipitation is about 39.5 inches per year, and average annual runoff is about 13 inches per year. The most productive aquifers are confined or unconfined outwash aquifers located along the major rivers. Bedrock aquifers are regionally insignificant but are the sole source of ground water for areas that lack outwash, alluvium, or sand and gravel lenses in till. Indiana has more than 17 billion short tons of recoverable coal reserves; about 11 percent can be mined by surface methods. Almost half of Indiana's surface reserves are in Clay, Owen, Sullivan, and Vigo Counties. More than 50,000 acres in west-central Indiana were disturbed by surface coal mining from 1941 through 1980. Big Slough and Hooker Creek are streams that drain unmined, agricultural watersheds. Row-crop corn and soybeans are the principal crops. Soils are moderately well-drained silt loams, and the watersheds have well-developed dendritic drainage systems. The unnamed tributary to Honey Creek and the unnamed tributary to Sulphur Creek are streams that drain mined and reclaimed watersheds. Ridges of mine spoil have been graded to a gently rolling topography. Soils are well drained and consist of 6 to 12 inches of silt-loam topsoil that was stockpiled and then replaced over shale and sandstone fragments of the graded mine spoil. Grasses and legumes form the vegetative cover in each watershed. Pond Creek and the unnamed tributary to Big Branch are streams that drain mined and unreclaimed watersheds. Approximately one-half of the Pond Creek watershed is unmined, agricultural land. Soils are very well-drained shaly silty loams that have formed or' steeply sloping spoil banks. Both watersheds contain numerous impoundments of water and have enclosed areas that do not contribute surface runoff to streamflow. The ridges of mine spoil are covered with pine trees, but much of the soil surface is devoid of vegetation.