Dams Are a Vital Part of the National Infrastructure

Dam Basics




Dams Are a Vital Part of the National Infrastructure

Water is one of our most precious resources; our lives depend on it. Throughout the history of humankind, people have built dams to maximize use of this vital resource.  

Dams provide a life-sustaining resource to people in all regions of the United States. 的y are an extremely important part of this nation’s infrastructure—equal in importance to bridges, 道路, 机场, 以及其他基础设施的主要元素. 它们可以同时发挥多种功能, 包括家庭用水供应, 农业, 工业, 和 community use; flood control; 娱乐; 和 clean, 通过水力发电实现可再生能源.

As populations have grown 和 moved to arid or flood-prone locations, 对大坝的需求增加了.



发电: 的 US is one of the largest producers of hydropower in the world, second only to Canada. 大坝发电量占全国电力需求的8- 12%.

可再生、清洁能源: 没有水电, the US would have to burn an additional 121 million tons of coal, 2700万桶石油, 还有7410亿立方英尺的天然气.

防洪: Dams built with the assistance of the 自然资源保育处 provide an estimated $1.7 billion in annual benefits in reduced flooding 和 erosion damage, 娱乐, 水的供应, 和野生动物栖息地. Dams owned 和 operated by the 田纳西流域管理局 produce electricity 和 prevent an average of about $280 million in flood damage each year.

水储存: Dams create reservoirs that supply water for a multitude of uses, 包括消防, 灌溉, 娱乐, 生活和工业用水供应, 和更多的.

灌溉: Ten percent of American cropl和 is irrigated using water stored behind dams.

导航: U.S. 美国陆军工程兵团的导航项目.S. serve 41 states, maintain 12,000 miles of channels, carry 15% of U.S. freight carried by inl和 waterways, operate 275 locks, 和 maintain 926 harbors.

娱乐: 水坝在美国各地提供了主要的娱乐设施.S. 美国的10%.S. 人口访问至少一个美国.S. 陆军工兵部队的设施.


Dam Basics

水坝的作用是蓄(蓄)水, wastewater or liquid borne materials for any of several reasons, 例如防洪, 人类的水供应, 灌溉, 牲畜供水, 能源发电, 矿山尾矿的围堵, 娱乐, 或污染控制. 许多水坝同时具备上述功能.

Manmade dams may be classified according to the type of construction material used, 施工中使用的方法, 坝的坡度或横截面, the way the dam resists the forces of the water pressure behind it, 用于防渗和防渗的手段, 偶尔, 根据大坝的用途.

用于建造水坝的材料包括土, 岩石, 采矿或磨矿的尾矿, 混凝土, 砌筑, 钢, 木材, miscellaneous materials (such as plastic or rubber) 和 any combination of these materials.

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路堤大坝: Embankment dams are the most common type of dam in use today. Materials used for embankment dams include natural soil or 岩石, or waste materials obtained from mining or milling operations. An embankment dam is termed an “earthfill” or “岩石fill” dam depending on whether it is comprised of compacted earth or mostly compacted or dumped 岩石. 的 ability of an embankment dam to resist the reservoir water pressure is primarily a result of the mass weight, type 和 strength of the materials from which the dam is made.                   

混凝土大坝: Concrete dams may be categorized according to the designs used to resist the stress due to reservoir water pressure. 混凝土坝的三种常见类型是: 重力, 支持 .

重力: Concrete 重力 dams are the most common form of 混凝土 dam. 的 mass weight of 混凝土 和 friction resist the reservoir water pressure. Gravity dams are constructed of vertical blocks of 混凝土 with flexible seals in the joints between the blocks.

支持: A 支持 dam is a specific type of 重力 dam in which the large mass of 混凝土 is reduced, 和 the forces are diverted to the dam foundation through vertical or sloping 支持es.

弓: Concrete 拱 dams are typically rather thin in cross-section. 的 reservoir water forces acting on an 拱 dam are carried laterally into the abutments.的 shape of the 拱 may resemble a segment of a circle or an ellipse, 拱门也可以在垂直平面上弯曲. Such dams are usually constructed of a series of thin vertical blocks that are keyed together; barriers to stop water from flowing are provided between blocks. Variations of 拱 dams include multi-拱 dams in which more than one curved section is used, 和 拱-重力 dams which combine some features of the two types of dams.



Because the purpose of a dam is to retain water effectively 和 safely, 水坝的蓄水能力是最重要的. Water may pass 从储层 to the downstream side of a dam by any of the following:

  • 通过主溢洪道或出口工程的
  • 越过辅助溢洪道
  • 超过三峡大坝
  • 桥台渗水
  • 坝下渗水

Overtopping of an embankment dam is very undesirable because the embankment materials may be eroded away (见视频的例子). Additionally, only a small number of 混凝土 dams have been designed to be overtopped. Water normally passes through the main spillway or outlet works; it should pass over an auxiliary spillway only during periods of high reservoir levels 和 high water inflow. 所有的堤坝和大多数的混凝土坝都有一些渗水. However, it is important to control the seepage to prevent internal erosion 和 instability. Proper dam construction, 和 maintenance 和 monitoring of seepage provide this control.


Intentional release of water is confined to water releases through outlet works 和 spillways. A dam typically has a principal or mechanical spillway 和 a drawdown facility. Additionally, some dams are equipped with auxiliary spillways to manage extreme floods.

出口工作原理:  In addition to spillways that ensure that the reservoir does not overtop the dam, outlet works may be provided so that water can be drawn continuously, 或根据需要, 从储层. 的y also provide a way to draw down the reservoir for repair or safety concerns. Water withdrawn may be discharged into the river below the dam, 运行发电机提供水力发电, 或者用于灌溉. 水坝出水口通常由管道组成, box culverts or tunnels with intake inverts near minimum reservoir level. Such outlets are provided with gates or valves to regulate the flow rate.

溢洪道:  的 most common type of spillway is an ungated 混凝土 chute. This chute may be located over the dam or through the abutment. 允许最大限度地使用存储卷, movable gates are sometimes installed above the crest to control discharge. 许多小型水坝有管道和立管溢洪道, 用于承载大多数流, 和 a vegetated earth or 岩石cut spillway through an abutment to carry infrequent high flood flows. 比如密西西比河上的水坝, flood discharges are of such magnitude that the spillway occupies the entire width of the dam 和 the overall structure appears as a succession of vertical piers supporting movable gates. High 拱-type dams in 岩石 canyons usually have downstream faces too steep for an overflow spillway. In Hoover Dam on the Colorado River, for example, a shaft spillway is used. 在竖井溢洪道, a vertical shaft upstream from the dam drains water 从储层 when the water level becomes high enough to enter the shaft or riser; the vertical shaft connects to a horizontal conduit through the dam or abutment into the river below.



全国大坝清单(NID) 已编目的有90多件,000 dams on America's waterways according to their hazard classification. Hazard classification is determined by the extent of damage a failure would cause downstream, with high-hazard potential dams resulting in loss of life 和 significant-hazard potential indicating a failure would not necessarily cause a loss of life, 但可能会导致重大的经济损失. 正如你在NID的这张地图上看到的, there are numerous dams across America 和 ensuring their safety is a critical goal.

安全是大坝有效运行的关键. 大坝溃坝对大坝所有者来说可能是毁灭性的, 大坝的预定用途和, 特别是, 对于下游的人口和财产. Property damage can range in the thous和s to billions of dollars. No price can be put on the lives that have been lost 和 could be lost in the future due to dam failure. Failures know no state boundaries—inundation from a dam failure could affect several states 和 large populations.

本世纪初, as many dams failed due to lack of proper engineering 和 maintenance, 人们认识到需要某种形式的管理. One of the earliest state programs was enacted in California in the 1920s. 联邦机构, such as the Corps of Engineers 和 the Department of 室内, 垦务局 built many dams during the early part of the twentieth century 和 established safety st和ards during this time. 慢慢地,其他州开始了监管项目. But it was not until the string of significant dam failures in the 1970s that awareness was raised to a new level among the states 和 the federal government.


Today, every state except Alabama has a dam safety regulatory program. State governments have regulatory responsibility for 70% of the approximately 90,全国水坝名录内的000座水坝. 的se programs vary in authority but, typically, the program activities include:

  • 既有大坝的安全评价
  • Review of plans 和 specifications for dam construction 和 major repair work
  • Periodic inspections of construction work on new 和 existing dams
  • 审查和批准紧急行动计划


的re are several federal government agencies involved with dam safety. Together, these federal agencies are responsible for five percent of the dams in the U.S. 的y construct, own 和 operate, regulate or provide technical assistance 和 rese拱 for dams. 这份名单包括农业部, 国防, 能源, 室内, Labor 和 State (International Boundary 和 Water Commission), 联邦能源管理委员会, 核管理委员会 和 the 田纳西流域管理局. 的 Federal Emergency Management Agency administers the National Dam Safety Program, a program established by law in 1996 to coordinate the federal effort through the Interagency Committee on Dam Safety, 通过财政拨款协助州大坝安全项目, 和 to provide rese拱 funding 和 coordination of technology transfer.


Federal agency representatives make up about 16% of the MGM集团美高梅登陆 membership. About 14% of dams in the USA are owned or regulated by federal agencies.

联邦紧急事务管理局, 国土安全部的一部分, does not own or regulate dams itself but administers the National Dam Safety Program, which coordinates all federal dam safety programs 和 assists states in improving their dam safety regulatory programs. 基础设施保护办公室, 也在国土安全部内部, leads a coordinated national program to reduce risks to the nation's critical infrastructure, 包括大坝, 恐怖主义行为造成的.

参与大坝安全的联邦机构, 作为所有者和/或监管者, 包括以下:

  • U.S. 农业部
    • 自然资源保育处
    • 农业研究服务
  • 国防部
    • 陆军工程兵团
    • 工程技术研究开发中心
    • 香港水利工程中心
  • 内政部
    • 印第安人事务局
    • 土地管理局
    • 垦务局
    • 鱼 & 野生动物服务
    • 国家公园管理局
    • 露天采矿办公室
  • 联邦能源管理委员会
  • 煤矿安全与健康管理局
  • 国际边界和水委员会.S. 部分)
  • 核管理委员会
  • 田纳西流域管理局

Together the agencies listed above make up the Interagency Committee on Dam Safety (ICODS), 作为国家大坝安全计划的负责人,由联邦应急管理局监督.

Other federal agencies that stay involved with MGM集团美高梅登陆 和 the dam safety community are the National Oceanic 和 Atmospheric Association (NOAA), 国家气象局和美国气象局.S. 地质调查所.