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Benbrook Lake (also known as Benbrook Reservoir) is a reservoir on the Clear Fork of the Trinity River in Tarrant County, Texas, USA. The lake is located approximately 10 miles (16 km) southwest of the center of Fort Worth, where the Clear Fork and the West Fork of the Trinity River join. The lake is impounded by the Benbrook Dam. The lake and dam are owned and operated by the U.S. Army Corps of Engineers, Fort Worth District. == History == Significant flooding on the Trinity River during May 1908, April 1922 and September 1936, was a primary cause for the development of Corps of Engineers flood control projects in North Texas. Benbrook Dam and Lake were built by the Galveston District of the Corps of Engineers. During the decade of active civil works construction following World War II, the U.S. Congress provided for the construction of Benbrook Lake, Grapevine Lake, Lavon Lake and Ray Roberts Lake as well as modifications to the existing Garza Dam for the construction of Lewisville Lake. The River & Harbors Act of 1945 authorized these projects for the purposes of both flood control and navigation. These lakes and others, along with an extensive floodway system of levees, are operated in a coordinated manner to minimize flooding along the Trinity River floodplain corridor in the Dallas/Fort Worth Metroplex. A second major influence for development was the desire of commercial interests for a shipping channel along the length of the Trinity River. This project, in its most grandiose design, was envisioned as a by canal (2.74 × 45.72 m) running upstream from Trinity Bay on the Gulf Coast to Dallas, and west all the way to Fort Worth. Downstream it would connect to the Houston Ship Channel. Twenty-six separate lock and dam projects were to be constructed. Today a ship channel is maintained upriver as far as river mile 41 (km 66) near Liberty, Texas. Although unlikely, a navigation channel linking Fort Worth to the Gulf of Mexico could still be constructed. Water originally intended for use in this navigation channel was only recently reallocated for municipal water use. The Tarrant Regional Water District in 1992 gained these water rights and now provides water supply to the cities of Benbrook, Fort Worth, and Weatherford. The Water District has also built pipelines that connect Benbrook Lake with the Fort Worth’s Rolling Hills water plant and both Cedar Creek and Richland-Chambers reservoirs southeast of Dallas. Construction of Benbrook dam began in May 1947, and was practically completed when floodgates were closed and deliberate impoundment was begun in September 1952. The cost to build the lake was $14.5 million ($112 million in 2007 dollars).〔(Federal Reserve of Minneapolis dollar worth calculator )〕 The rolled-earth embankment is 9,130 feet (2,783 m) in length, including the concrete spillway, and rises 130 feet (39.6 m) above the streambed to an elevation of 747 feet (227.7 m) above sea level. A pair of × sliding gates operated by electric cable hoists controls the floodwater releases through the . Two 30-inch-diameter pipes (0.76 m) are provided for low-flow releases to maintain downstream river flows. The concrete spillway for uncontrolled releases is 500 feet (152 m) long, with a in its center. At the normal, or conservation pool, level of above sea level, the lake covers 3,770 acres (15 km²). This would increase to 7,630 acres (31 km²) if the lake ever reaches the nominal maximum flood pool elevation of 724, which is also the overall spillway elevation at the top of the center notch. One design option considered during the planning stages for the lake included an alternate damsite near the current I-20 bridge over the Trinity River, 3.7 feet (1.1 m) downstream from the final, chosen location. There was much more to construction than simply building the dam. Several railroads, roads and bridges, utility lines and cemeteries were relocated. The largest of these jobs was the rerouting of six miles (10 km) of the Gulf, Colorado and Santa Fe Railway. Gravesites from seven separate cemeteries were relocated to the Benbrook municipal cemetery at Winscott and Mercedes. No significant cultural, archeological or paleontological features existed in the project area, according to the July 1948 preconstruction survey. 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「Benbrook Lake」の詳細全文を読む スポンサード リンク
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