|
Rock Creek is a free-flowing tributary of the Potomac River, which empties into the Atlantic Ocean via the Chesapeake Bay. The creek is long,〔U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. (The National Map ), accessed August 15, 2011〕 with a drainage area of about . The last quarter-mile (400 m) of the creek is affected by tides.〔U.S. Geological Survey, Baltimore, MD, 2002. (''Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999-2000.'' ) Anita L. Anderson et al. Water-Resources Investigations Report 02-4067.〕 ==Geography== The creek rises from a spring near Laytonsville in Montgomery County, in the U.S. state of Maryland, and joins the Potomac near Georgetown and the Watergate in Washington, D.C. Beginning in the Derwood–Rockville area in Maryland, the creek flows through (Rock Creek Regional Park ) southward to the D.C. boundary. About of the creek flow though Rock Creek Park in Washington, where it is fed by several small creeks — Piney Branch, Pinehurst Branch, Broad Branch, Soapstone Branch, and Luzon Branch — and numerous storm sewers. The Chesapeake and Ohio Canal joins Rock Creek in Georgetown, and used the mouth of Rock Creek as its terminus in Georgetown. At the Tidewater Lock, the creek (and the Canal) empty into the Potomac River. This area, called the "Rock Creek Basin" by the Canal Company, which included a mole, causeway, and waste weir was completed in 1831.〔 p. 251〕 Subject to silting up, it was dredged several times for the Canal's use.〔Unrau p. 22〕 The Maryland portion of the watershed comprises the second-largest watershed in Montgomery County, about . About 21 percent of the creek's watershed is in Washington. Total land usage in the watershed is of wetlands or water, of residential and commercial areas, of forest or grasslands, and of agricultural areas. The creek has a fairly steep gradient, with rapid changes in elevation. The man-made Lake Needwood is located on the creek, north of Rockville. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Rock Creek (Potomac River)」の詳細全文を読む スポンサード リンク
|