Areal variation of suspended-sediment yields within and adjacent to the coal fields of the Eastern Coal Province and the eastern region of the Interior Coal Province

Mean annual suspended sediment yields are shown at stations in and around the coal fields of the Eastern Coal province and the eastern region of the Interior Coal Province. All stations are on smaller basins with areas of 100 to 1,000 sq km or larger basins with areas of 1,000 to 10,000 sq km. Background sediment yields vary from < 25 kg/sq km/yr in the eastern part off the study area to > 300 mg/sq km/yr in the west. Background yields < 25 mg/sq km/yr in the eastern part of the study area approximate yields from undisturbed, forested basins. Background yields of > 200 mg/sq km/yr in western Illinois and adjacent parts of Missouri and Iowa appear to reflect the presence of thick deposits of Loess. Sediment yields > 200 mg/sq km/yr above background in southeastern Pennsylvania and in western Illinois and adjacent Iowa and Missouri reflect a variety of factors. Large yields in southeastern Pennsylvania reflect coal mining and other human activities. The data suggest that the large yields in western Illinois and adjacent Iowa and Missouri are due partly to the thick deposits of loess in this area. Large sediment yields above background in West Virginia and eastern Kentucky reflect coal production and topography. The areas containing stations that have sediment yields > 200 mg/sq km/yr above background correspond to the counties in which mean annual coal production from surface mines is at least 2 million metric tons. Contour mining, used extensively in West Virginia and eastern kentucky because of the steep slopes, makes large amounts of material available for transport in surface runoff and streamflow