CEOR CHAP5 - WATER RESOURCES ENGINEERING

Water resources engineering

is a specialty dealing with the use of water in support of modern living, including the agricultural, industrial, domestic, recreational, and environmental needs

Water resources engineering

Its scope includes the finding and preservation of above and underground water sources, understanding the movement of water in nature, engineering the transport of water, and managing erosive effects of water wave and current on shorelines

system analysis

The application of ______ in water resources management and the design and operations of multipurpose reservoir and river systems is at the core of water resources system engineering.

Hydrologic Cycle

Explains how water moves around in our planet

Hydrologic Cycle

Water molecules from one location to another are driven by the solar energy. Moisture circulates from the earth into the atmosphere through evaporation and then back into the earth as precipitation. In going through this process, called the _______

Precipitation, Runoff, Storage, Evapotranspiration

The hydrologic cycle consists of four key components:

Precipitation

occurs when atmospheric moisture becomes too great to remain suspended in clouds

Precipitation

It denotes all forms of water that reach the earth from the atmosphere, the usual forms being rainfall, snowfall, hail, frost and dew. Once it reaches the earth's surface, _________ can become surface water runoff, surface water storage, glacial ice, water for plants, groundwater, or may evaporate and return immediately to the atmosphere

Precipitation

It's usual forms are rainfall, snowfall, hail, frost, and dew

Runoff

Once it reaches the Earth's surface, precipitation becomes surface ______

Rainfall

is the predominant form of precipitation and its distribution over the world and within a country

Runoff

is the water that flows across the land surface after a storm event.

Storage

Portion of the precipitation falling on land surface which does not flow out as runoff gets stored as either as surface water bodies like Lakes, Reservoirs and Wetlands or as sub-surface water body, usually called Groundwater.

Groundwater

sub-surface water body,

Groundwater storage

The water infiltrating though the soil cover of a land surface and traveling further to reach the huge body of water underground

Evapotranspiration

actually the combination of two terms - evaporation and transpiration.

Evaporation

the process of liquid converting into vapour, through wind action and solar radiation and returning to the atmosphere.

Evaporation

is the cause of loss of water from open bodies of water, such as lakes, rivers, the oceans and the land surface.

Transpiration

is the process by which water molecules leaves the body of a living plant and escapes to the atmosphere

Evapotranspiration

therefore, includes all evaporation from water and land surfaces, as well as transpiration alled the availability of water from plants

Groundwater Recharge

It affects the availability of water

Groundwater Recharge

Some of the water that precipitates, flows on ground surface or seeps through soil first, then flows laterally and some continues to percolate deeper into the soil.

Groundwater Recharge

This body of water will eventually reach a saturated zone and replenish or recharge groundwater supply.

Groundwater Recharge

the recuperation of groundwater which is done to increase the groundwater table elevation

Aquifers

Some of the water that precipitates, flows on ground surface or seeps through soil first, then flows laterally and some continues to percolate deeper into the soil, the water is then stored into underground water storages called _______

sustainable development

implies that development meets the needs of the present life, without compromising on the ability of the future generation to meet their own needs.

sustainable development

would ensure minimum adverse impacts on the quality of air, water and terrestrial environment.

Hydraulic Engineers

design artificial waterways such as canals, channels, and aqueducts as well an manage water movement by designing and constructing dams, levees, canal locks, and other water-regulating devices

flood prevention and control

For many regions a major task of hydraulic engineers is _________ , which entails the assessment of potential rainfall quantity, prediction of water levels along natüral rivers, streams, or channels, and strategies to mitigate flooding hazards by improving the natural topography.

Hydraulic Engineers

They study rainfall data (from PAGASA) and predict water levels.

Fluid

is a term that describes both gases and liquids

Fluid

Substance that can flow

Surface tension

results from a different molecular bonding condition at the free surface compared to bonds within the liquid.

cohesion, adhesion

in water, surface tension results in properties called _____ and ______

cohesion

enables water to resist a slight tensile stress

adhesion

enables water molecules to adhere to another body

cohesion

allows water molecules to stick to eachother

Capillarity

allows liquid to rise up and fall down

Capillarity

is a property of liquids that results from surface tension in which the liquid rises up or is depressed down a thin tube.

adhesion, cohesion

If ______ predominates over _____ in a liquid, as in water, the liquid will wet the surface of a tube and rise up.

cohesion, adhesion

If ______ predominates over _____ in a liquid, as in mercury, the liquid does not wet the tube and is depressed down

specific weight

how heavy a certain material is at a given space

specific weight

defined as weight per unit volume.

density

mass per unit volume

Dense

called when a material is packed tightly

specific gravity

how heavy a liquid is in comparison to water

specific gravity

____ of a liquid is the ratio of its specific weight to that of pure water at a standard temperature and should not be confused with the term specific weight. It is dimensionless

hydrostatic

refers to the study of water at rest

hydrostatic

Fundamental to the study is the concept of pressure resulting from the weight of water.

piezometer

Device used to measure low hydrostatic pressure

piezometer

is a simple tube, connected to a body of water with its other end open to the atmosphere

manometer

When the water pressure to be measured is relatively high, a piezometer may be inadequate, and ______ must be used

manometer

A high pressure would require a long piezometer tube, but a _______ solves this proble by the use of a heavy liquid such as mercury

Buoyancy

the uplifting force exerted by water on a submerged solid object

hydrodynamics

Study of how water flows or moves (water in motion)

Conservation of mass, conservation of energy

Fundamental to hydrodynamics are the concepts of _____ and _______

Pipe

Water can move In all directions (such as when a glass of water is spilled on the floor), or it can be channeled into a prevailing direction such as flow in a _____

velocity, discharge

Two fundamental parameters are used to describe the motion of water confined to a conduit: _______, and _____ (or rate of flow)

Velocity, v

____, symbol: ____, describes the rate of change of position of the water particles as defined in fundamental mechanics.

Velocity of flow

However, since all the particles flowing in a conduit move at slightly different speeds, the ___________ is the average speed of all the particles at a certain point in a pipe

Conduits

Natural or artificial channels

Velocity of flow

then, is defined as the average velocity of all water particles crossing an imaginary plane perpendicular to the direction of motion at a particular location along the conduit

Discharge, Q

______, symbol: ___, rate of flow, describes the amount of water passing through an imaginary plane per unit time at a particular location-along the conduit

Laminar flow

The flow is orderly, describes smooth flow of water with relatively low velocity.

Turbulent flow

As velocity increases, flow becomes rougher with pulsating crosscurrents within the conduit. This type of flow is called

Steady flow

occurs when discharge is unchanged over time

Unsteady flow

results from a relatively rapid change of discharge, such as the opening of a gate or closing of a valve

Uniform flow

occurs when the cross-sectional area of the conduit remains constant.

Energy

in solving hydraulic problems, concepts of _____ are used extensively

Energy Head

Height or level of energy that water has, how high or pressurized water is at a given point

Energy Head

The fluid nature of water does not allow a given quantity to remain conveniently in place when it moves making us unable to measure its energy, thus ____ is used

Energy Head

used to describe the energy of water in solving hydraulic problems

Position Head

describes potential energy per unit weight of a mass of water due to the height of the water above some datum

(Energy of water based on height)

Pressure Head

describes potential energy per unit weight of a mass of water due to the pressure exerted from above

(Energy of water based on pressure)

Head Loss

describes the loss of energy per unit weight of a mass of water due to friction and turbulence

(Energy loss of water due to friction)

Hydraulic devices

are structures that use hydraulic principles to control the flow of water

Velocity Head

describes kinetic energy per unit weight of a mass of water due to kinetic energy resulting from its motion

(Energy of water based on movement)

Orifice

is a hole in the wall of a container through which water may flow.

Weir

is a structure that, like an orifice, regulates the flow of water out of an impoundment or reservoir, ex. Dams

Open Channel Hydraulics

Study of water when it is freely moving

Open Channel Hydraulics

is the study of the mechanics of water flowing in open conduits, which generally include channels, streams, and even pipes (not flowing under pressure

flood

Happens when water stays/accumulates/rises on a portion of land that is usually dry

flood

is defined as a 'great flow of water... especially, a body of water, rising, swelling, and over-flowing land not usually thus covered;

Flood control

implies all measures taken to reduce the detrimental effects of flood

River Flooding

This is the major cause of flooding extensive areas as a result of heavy rains in the catchment areas as well as local areas thereby increasing the river levels

Flash Floods

This result due to heavy rains in hilly areas which cause local rivers and small streams to rise to dangerous level within a short period of time say 6 to 12 hours.

Urban Flooding

Local heavy rains up to 100 mm or more in a day over the city and larger towns can cause damaging and disruptive flooding due to poor or chocked drainage and rapid runoff.

Strom Surge or Tidal Floodings

This result mostly due to tropical disturbances, developing to cyclones and crossing surrounding coastlines

Short-term Measures

These measures are adopted for giving quick results when immediate relief to some pockets or locations is felt necessary

Short-term Measures

(flood management measure) constructions of embankments along the low-level banks that are subject to frequent flood spells.

Short-term Measures

(flood management measure)

Construction of raised platforms for temporary shelter during flood.

Short-term Measures

(flood management measure) Dewatering by pumps of flooded pockets, towns when gravity discharge of floodwater is not possible.

Short-term Measures

(flood management measure)

Construction of floodwalls near congested areas of cities, towns and industrial belts.

Long-term Measures

(flood management measure) Construction of storage reservoirs to moderate the flow peak thereby ensuring regulation of flood downstream.

Long-term Measures

(flood management measure)

Integrated watershed management in the hilly area catchment, which ensures reduction in surface runoff, erosion and increase of infiltration capacity thereby reducing the impact of flood

Long-term Measures

(flood management measure) Flood forecasts and warning based on hydro-geomorphological studies which can be given with some Tead period, thereby ensuring minimization of property loss and loss of human life by shifting them to safer places

Modify flooding by structural means

To reduce losses due to flood the strategies to be followed can be stated as follows:

herein the strategies to be followed involves constructions of dams, dikes, levees, channel alterations, high flow diversions and land treatment. The main idea is to keep water away from the potential damage areas

Flood Forecasting

To reduce losses due to flood the strategies to be followed can be stated as follows:

Here, forecast of flooding is provided at the potential damage points. The population both human as well as livestock and the movable properties are shifted to a safer place if there is a chance of flood damage. Herein the objective is to keep people away from inundated areas

Modify susceptibility to flood damage

To reduce losses due to flood the strategies to be followed can be stated as follows:

Regulations are frames to avoid undesirable or unwise rise of flood plains. Necessary steps are taken to modify the impact of flooding through individual or group action designed for assisting people in the preparatory, survival and recovery phase of floods which are namely through education and information on floods, flood insurance, taxation relief, etc

Spillways

are invariably provided in storage dams for safe disposal of the excess water flowing into the reservoir after it has filled up