HYDROLOGY

• DAM


  A barrier that stops or restricts the flow of water or underground streams
• Reservoirs created by dams

  • Suppress floods
  • Provide water for irrigation, human consumption, industrial use, aquaculture, and navigability
• Dams


  • Essential water engineering resources
  • Help meet the growing demand for water, energy, and flood protection in many parts of the world
• Purposes of dam


  • Irrigation
  • Hydropower
  • Flood prevention
  • Water supply
  • Inland navigation
• Irrigation


  The main purpose of constructing a dam is to store water and use it for irrigation
• Irrigation


  • Provide water for farming
  • Divert rivers into canals or pipelines to irrigate land many miles away
  • Used when a river flows at a lower elevation than the land to be irrigated
• Hydropower


  Considered the largest renewable energy source of electricity and clean because it does not contribute to global warming, air pollution, acid rain, or ozone depletion
• Hydropower

  Power dams are expected to generate enough electricity to repay the cost of construction
• Hydropower


  The most common type of hydroelectric power plant is an impoundment facility
• Impoundment facility

  • Uses a dam to store river water in a reservoir
  • Water released from the reservoir flows through a turbine, spinning it, which in turn activates a generator to produce electricity
• Flood prevention

  Flood control is a significant purpose for many of the existing dams and continues as the main purpose for some of the major dams of the world currently under construction
• Flood prevention

  • The dams are used to effectively regulate the level of water flowing in the river by temporarily storing the flood volume and releasing it later
  • Dams can also help to prevent the great loss of life and property caused by flooding
• Water supply


  Dams play an important role in the water supply for domestic and industrial use
• Water supply

  • Dams store the water and supply it during the shortage of times
  • Only 2% of the total is infiltrated to replenish the groundwater
  • Properly planned, designed and constructed and maintained dams to store water contribute significantly toward fulfilling our water supply requirements
• Inland navigation


  Dams just not only serve as an irrigational lifeline, but also provide inland navigation throughout the heartland of the nation
• Inland navigation


  • The advantages of inland navigation, however, when compared with highway and rail are the large load-carrying capacity of each barge, the ability to handle cargo with large
• Classification of dams according to use

  • Storage dam
  • Diversion dam
  • Detention dam
• Storage dam


  Constructed to store water for extended lengths of time
• Storage dam


  • Stores water during the rainy season when there is large flow in the river
  • The stored water then can be used for irrigation, livestock, municipal water supply, recreation, and hydroelectric power generation
• Diversion dam


  Constructed for the purpose of diverting water into an off taking canal
• Diversion dam


  • Provide pressure to push water into ditches, canals, or other areas used for conveyance
  • Typically lower in height and have a small water storage area in its upstream
• Detention dam


  Specifically constructed for flood control
• Detention dam


  • Retards the flow of water in the river on its downstream by storing some flood water, that helps reduce flash floods
  • The water is retained in a reservoir to be later gradually released
• Classification of dams according to structural behavior

  • Gravity dam
  • Arch dam
  • Buttress dam
  • Earthen dam
  • Rockfill dam
• Gravity dam


  A solid structure typically made of concrete or stone masonry, constructed across a river to create a reservoir on its upstream
• Gravity dam


  • Rely on their own weight and resistance to hold back the force of water
  • Designed to withstand loads through the force of gravity
  • Considered one of the most reliable types of dams
• Arch dam


  Curved in plan, and most of their water load is carried by the abutment of the arch horizontally
• Arch dam


  • The amount of water load it can withstand is determined by its arch or curvature
• Buttress dam


  Consist of a sloping deck supported by intervals of buttresses
• Types of buttress dams

  • Multiple arch type
  • Massive head type
  • Deck type
• Buttress dams


  • Usually use less concrete than other dams but are not necessarily cheaper
• Earthen dam


  Constructed using natural materials such as soil, clay, and rock
• Earthen dam


  • Materials are compacted to form a barrier that holds back water, creating a reservoir or lake
  • Can range in size from small structures used for irrigation or water storage to large dams used for hydroelectric power generation and flood control
• Rockfill dam


  Mainly made from dumped and compacted rock fill
• Rockfill dam


  • Permeable
  • Have an impermeable core or an impermeable layer on the upstream face of the dam to prevent seepage through the porous core
  • The impermeable parts are usually made of reinforced concrete, asphaltic concrete or clay
• Classification of dams according to material

  • Rigid dams
  • Non-rigid dams
• Rigid dam


  Typically made of materials such as concrete or masonry and are designed to resist the pressure of water through their own weight and strength
• Non-rigid dam


  Constructed with flexible materials such as earth, rock, or timber, and rely on their shape and the resistance of the materials to hold back the water
• Rigid vs Non-rigid dams

  • Rigid dams are usually more suitable for larger water bodies and can provide greater stability, while non-rigid dams are often used for smaller water bodies and can be more adaptable to the natural environment
• Classification of dams according to hydraulic design

  • Overflow dams
  • Non-overflow dams