Spillway is a dam designed to pass water from the upstream side of a dam to the downstream side and dry dam for controlling flood.
Chapter 6. The Determination & Design of Dam Components 36 Design & Construction Guidelines for Dams in Texas dam is suspected to have a high potential for liquefaction, and piezometers are being installed as a result, there may not be an alternative to drilling into the core zone.  A diversionary dam is a structure designed to divert all or a portion of the flow of a river from its natural course. The water may be redirected into a canal or tunnel for irrigation and/or hydroelectric power production. Furthermore, the designer tries to shape the dam so if one were to consider the part of dam above any particular height to be a whole dam itself, that dam also would be held in place by gravity. i.e. there is no tension in the upstream face of the dam holding the top of the dam down. A spillway is a section of a dam designed to pass water from the upstream side of a dam to the downstream side. Many spillways have floodgates designed to control the flow through the spillway. Types of spillway include: A service spillway or primary spillway passes normal flow. Furthermore, the designer tries to shape the dam so if one were to consider the part of dam above any particular height to be a whole dam itself, that dam also would be held in place by gravity. i.e. there is no tension in the upstream face of the dam holding the top of the dam down. Dam design and construction methods for the most usual types of large dams are presented and justified in section four. The possibility and usefulness of building as many dams in the 21 st century as have been built in the 20 th is analyzed in section six. This type of dam proved to have the safest design with few failures before 1930, and only one such failure occurred among the 2 500 large dams built later. Very large structures were built, each using millions of m 3 of concrete. Therefore, dams are constructed for a specific purpose such as water supply, flood control, irrigation, navigation, sedimentation control, and hydropower. A dam is the cornerstone in the development and management of water resources development of a river basin. In addition to the economic benefits, a river that has been developed with dams and reservoirs for navigation may also provide additional benefits of flood control, reduced erosion, stabilized groundwater levels throughout the system and recreation. Successful dams require planning, proper site assessment, design, construction and maintenance. Without this attention to detail, dams are in danger of washing out. Dam construction is not a do-it-yourself type of project. The dam must be constructed from an impervious (clay or clay-based) material. A simple field test to determine the suitability of the material for compaction requires adding a small amount of moisture to a handful of material and then mixing to the consistency of putty. In ancient times, dams were built for the single purpose of water supply or irrigation. As civilizations developed, there was a greater need for water supply, irrigation, flood control, navigation, water quality, sediment control and energy. In addition to the economic benefits, a river that has been developed with dams and reservoirs for navigation may also provide additional benefits of flood control, reduced erosion, stabilized groundwater levels throughout the system and recreation. The spillway is a critical part of dam construction. An under-designed spillway will result in the dam overtopping or serious spillway erosion during peak runoff. These situations can cause major water losses, potential flooding and damage downstream, in addition to the costs to repair the dam. The dam must be constructed from an impervious (clay or clay-based) material. A simple field test to determine the suitability of the material for compaction requires adding a small amount of moisture to a handful of material and then mixing to the consistency of putty. A dry dam also known as a flood retarding structure, is a dam designed to control flooding. It normally holds back no water and allows the channel to flow freely, except during periods of intense flow that would otherwise cause flooding downstream. Furthermore, the designer tries to shape the dam so if one were to consider the part of dam above any particular height to be a whole dam itself, that dam also would be held in place by gravity. i.e. there is no tension in the upstream face of the dam holding the top of the dam down. Dams andstakeholders. 2 Dams-large and smallAlthough dams have been built in the world since timesimmemorial, large dam construction was earlier notpossible though needed, because of lack of adequatedesign knowledge, construction equipment, newmaterials like cement and concrete and technology ofconstruction. On the other hand, in many situations,raising and strengthening of dams is called for, forimproving the irrigation service. Dam builders have notsufficiently considered so far, ‘decommissioning of dams’as a necessary step. Dams are complex and majorstructures involving large investments.
http://www.tceq.state.tx.us/publications/rg/rg-473.html/at_download/file https://en.wikipedia.org/wiki/Dam https://en.wikipedia.org/wiki/Dam http://www.hydrocoop.org/dam-design-construction-reservoirs-balancing-lakes/ http://www.icold-cigb.org/GB/Dams/role_of_dams.asp http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex4613 http://www.icold-cigb.org/GB/Dams/role_of_dams.asp http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex4613 https://en.wikipedia.org/wiki/Dam http://www.icid.org/dam_pdf.pdf
what are dams designed to do