HYDRO 1

HYDROLOGY

• means the science of water.

• Science that deals with the occurrence, circulation, and distribution of water of the earth and the earth’s atmosphere.

• Concerned with the water in streams and lakes, rainfall and snowfall, snow and ice on the land and water occurring below the earth’s surface in the pores of the soil and rocks,

SCIENTIFIC HYDROLOGY

the study which is concerned chiefly with academic aspects.

APPLIED HYDROLOGY

a study concerned with engineering applications.

SCIENTIFIC AND APPLIED HYDROLOGY

CLASSIFICATIONS OF HYDROLOGY

1. Estimation of water resources
2. The study of processes such as precipitation, runoff,
evapotranspiration and their interactions
3. The study such as floods and droughts, and the
strategies to combat them.

ENGINEERING HYDROLOGY DEALS WITH:

HYDROLOGIST

scientists who study hydrology (water and its movement).

1. Help solve local and global problems related to the
overabundance, scarcity, or the quality of water by
using their understanding of various physical,
chemical, and biological processes in the water
cycle and soil-water system,
2. Undertake a wide range of activities to monitor,
manage and protect the water environment.
3. Tasks include:
• Design and operation of hydraulic structures
• Water supply
• Wastewater treatment and disposal
• Irrigation
• Drainage
• Hydropower generation
• Flood control
• Navigation
• Erosion and sediment control
• Salinity control
• Pollution abatement
• Recreation use of water
• Fish and wildlife protection

ROLES OF HYDROLOGIST

• Hydrologic design provides a service. • Level of service must be defined, and acceptable risk of failure must be determined (local drainage ordinances) • Cost and site characteristics are typical constraints. • Occurrence, timing and amount are the key aspects of hydrology from an engineering perspective. • Problems are created by lack of water or too much water in a location at a moment in time.

IMPORTANCE OF HYDROLOGIC ENGINEERING DESIGN

HYDROLOGIC CYLE

also known as water cycle

• cycle that involves the continuous circulation of water in the Earth atmosphere system.

OCEAN

STARTING POINT OF HYDROLOGIC CYCLE

• Transportation of water

• Temporary storage

• Change of state

Each path of the hydrologic cycle involves one or more of the following aspects:

EVAPORATION

– occurs when the physical state of water is changed from a liquid state to a gaseous state which is caused by solar radiation and other factors such as air temperature, vapor pressure, wind and atmospheric pressure.

CONDENSATION

the process by which water vapor changes its physical state from a vapor, most commonly, to a liquid.

PRECIPITATION

– process that occurs when any and all forms of water particles fall from the atmosphere and reach the ground.

INTERCEPTION

– the process of interrupting the movement of water in the chain of transportation events leading to streams.

INFILTRATION

the physical process involving movement of water through the boundary area where the atmosphere interfaces with the soil.

PERCOLATION

the movement of water through the soil, and its layers by gravity and capillary forces.

TRANSPIRATION

– biological process that occurs mostly in the day wherein water inside of plants is transferred from the plant to the atmosphere as water vapor through numerous individual leave openings.

EVAPOTRANSPIRATION

\- the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants

RUNOFF

also known as flood, is a flow from a drainage basin or watershed that appears in surface streams

ATMOSPHERE

EARTH’S SURFACE

GROUND

THREE BASIC LOCATIONS OF WATER STORAGE

METEOROLOGY

• science that deals with the study of the atmosphere and its phenomena especially with weather.

• Scientific study of the atmosphere that focuses on weather processes and forecasting

METEOROLOGIST

scientist that studies weather, climate, and the forces that causes changes in our environment.

WEATHER

Mix of events that happen each day in the atmosphere, different in different parts of the world and changes over a short period of time.

• Mostly happens in troposphere.

o Wind (movement of air)

o Precipitation (rain, snow)

o Temperature (hot, cold)

o Sunshine

o Humidity (absolute, relative)

o Pressure

o Cloud

o Visibility

Condition of the atmosphere at a particular place over a short period of time in terms of:

SUN

AIR PRESSURE

WIND

1ST SET OF WEATHER ELEMENTS

CLIMATE

An average portrait of weather conditions in a specific place over a long period of time. (20 – 1,000,000 years)

RAINFALL

TEMPERATURE

Climate is determined by:

LATITUDE

ELEVATION

OCEAN CURRENTS

CLIMATE ARE INFLUENCED BY:

WHERE PEOPLE LIVE

HOW PEOPLE LIVE

WHAT THEY GROW AND EAT

CLIMATE AFFECTS THE FF:

CLIMATE OF THE PH

Tropical and maritime

• Characterized by relatively high temperature, high humidity, and abundant material.

• Similar in many aspects to the climate of the countries in Central America

• Most important elements are temperature, humidity, and rainfall.

TEMPERATURE

The measure of the average heat or thermal energy in a substance.

DISTANCE FROM THE EQUATOR

HEIGHT ABOVE THE SEA LEVEL

WEATHER PATTERNS

The temperature in the atmosphere changes due to ______,___ __AND__ __

latitude, altitude

____ __an insignificant factor in the variation of temperature while__ ____ shows greater contrast in temperature.

HUMIDITY

• Refers to the moisture content of the atmosphere.

• The concentration of water vapor present in the air.

• The more water in the vapor, the higher the humidity.

heat causes water to evaporate faster.

Hot places tend to be more humid than cool places because

ABSOLUTE HUMIDITY

used to describe the actual amount of water vapor that is saturating the air. It is calculated by finding the mass of water vapor in an area and dividing it by the mass of air in the same area.

RELATIVE HUMIDITY

refers to on meteorologist’s weather reports, and it describes the amount of water vapor in the area as opposed to how much water vapor could be in the area. It is calculated by getting the ratio of the absolute humidity and the potential amount of water saturation that the air could possibly hold.

SPECIFIC HUMIDITY

used as a ratio of the amount of water vapor in the air to the amount of dry air in the area.

RAINFALL

The most important climatic element in the Philippines

SEASON

Weather during specific part of the year

CLIMATE TYPE 2

no dry season with a very pronounced maximum rain period from December to February. There is not a single dry month. Minimum monthly rainfall occurs during the period from March to May.

CLIMATE TYPE 1

two pronounced seasons: dry from November to April and wet during the rest of the year. Maximum rain period is from June to September.

CLIMATE TYPE 3

No very pronounced maximum rain period with a dry season lasting only from one to three months, either during the period from December to February or from March to May. This type resembles type I since it has short dry season

CLIMATE TYPE 4

rainfall is more or less evenly distributed throughout the year. This type resembles type II since it has no dry season.

CATCHMENT AREA

Area of land draining into a stream or a water course at a given location.

• Also called as a drainage area or a drainage basin.

CLOUDS

• Mass of small water droplets or tiny ice crystals that float in the air.

• Formed when the temperature of the air is below the dew point.

HIGH CLOUDS

Made of ice crystals due to the cold air in the upper sky

• The base of a high cloud above the surface can be anywhere from 6000 to 18000 meters in the tropics to 3000-8000 meters in the polar regions.

CIRRUS CLOUDS

o the most common of the high cloud (5000 – 13000 meters) group.

o Composed entirely of ice and consist of long, thin, wispy, streamers.

o Commonly known as “Mare’s Tails” because of its appearance.

o Usually white and predict fair weather.

CIRROSTRATUS CLOUDS

o Sheet like thin clouds that usually cover the entire sky

o The sun or moon can shine through cirrostratus clouds, and sometimes, they will appear to have a halo around it. The ice crystals from the cloud refracts the light from the sun or moon, creating a halo.

o Usually come 12-24 hours before a rain or snowstorm.

CIRROCUMULUS CLOUDS

o Small, rounded puffs that usually appear in long rows. o Usually white but sometimes appear gray.

o The same size or smaller that the width of the littlest finger when you hold up your hand at arm’s length.

o Cover a lot of the sky, called a “Mackerel Sky” because the sky looks like the scales of a fish.

o Usually seen in the wintertime and indicate fair, but cold weather.

MIDDLE CLOUDS

• Consists of altostratus and altocumulus clouds.

• Made of ice crystals and water droplets.

• The base of a middle cloud above the surface can be anywhere from 2000 – 8000 meters in the tropics to 2000 – 4000 meters in the polar regions.

ALTOSTRATUS CLOUDS

o Usually covers the whole sky and has a gray or bluegray appearance.

o The sun or moon may shine through an altostratus cloud, but will appear watery or fuzzy.

o Forms ahead of storms with continuous rain or snow. Occasionally, rain will fall from an altostratus cloud. If the rain hits the ground, then the cloud becomes classified as a nimbostratus cloud.

ALTOCUMULUS CLOUDS

o Grayish white with one part of the cloud darker than the other.

o Usually form in groups and are about 1 km thick.

o About as wide as your thumb when you hold up your hand at arm’s length to look at the cloud. o If an altocumulus clouds on a warm humid morning, then expect thunderstorms by late afternoon.

LOW CLOUDS

• Consists of water droplets.

• The base of a low cloud is from the ground surface to 2000 meters.

STRATUS CLOUDS

o Uniformly gray in color and can cover most or all of the sky.

o Can look like a fog that doesn’t reach the ground.

o Light mist or drizzle is sometimes associated with stratus clouds.

STRATOCUMULUS CLOUDS

o Low, lumpy, and gray.

o Look like cells under a microscope – sometimes they line up in a rows and other times they spread out.

o Only light precipitation, generally in the form of drizzle, occurs with stratocumulus clouds.

NIMBOSTRATUS CLOUDS

o Dark gray with a ragged base.

o Associated with continuous rain or snow.

o Sometimes they cover the whole sky, and you can’t see the edges of the cloud.

CLOUDS WITH VERTICAL GROWTH

• Include cumulus and cumulonimbus clouds.

• Grow high up into the atmosphere rather than spreading across the sky.

• Span all levels of the troposphere and can even rise into the stratosphere.

CUMULUS CLOUDS

o Puffy white or light gray clouds that look like floating cotton balls.

o Have sharp outlines and a flat base. o Have a base height of 1000 meters and a width of 1 kilometer.

o Can be associated with good or bad weather. Cumulus humilis clouds are associated with fair weather. Cumulus congestus clouds are usually associated with bad weather.

o Their tops look like cauliflower heads and mean that light to heavy showers can occur.

CUMULONIMBUS CLOUDS

o Generally known as thunderstorm clouds.

o Can group up to 10 kilometers high. At this height, high winds will flatten the top of the cloud out into an anvil-like shape.

o Associated with heavy rain, snow, hail, lightning, and tornadoes

LENTICULAR CLOUDS

o Form on the downwind side of mountains. Wind blows most types of clouds across the sky, but lenticular clouds seem to stay in one place.

o Air moves up and over a mountain, and at the point where the air goes past the mountaintop the lenticular cloud forms and then the air evaporates on the side farther away from the mountains.

KELVIN-HELMHOLTZ CLOUDS

o Look like breaking waves in the ocean. After wind blows up and over a barrier, like a mountain, the air continues flowing through the atmosphere in a pattern that looks like a wave.

o Form when there is a difference in the wind speed or direction between two wind currents in the atmosphere.

MAMMATUS CLOUDS

o Pouches of clouds that hang underneath the base of a cloud.

o Usually seen with cumulonimbus clouds that produce very strong storms. o Sometimes describes as looking like a field of tennis balls or melons, or like female human breasts.

o The name “mammatus” comes from the Latin word mamma, or breast.

CONTRAILS

o White streaks coming off high-flying jet airplanes are called contrails, a short term for condensation trails.

o Formed when water vapor condenses and freezes around small particles that exist in aircraft exhaust. The water vapor comes from the air around the plane and the exhaust of the aircraft.

o Some contrails evaporate quickly while others stay in the sky for a long time after the airplane is gone. These contrails can become human-made cirrus clouds.

SHORT-LIVED CONTRAILS

PERSISTENT NON-SPREADING CONTRAILS

PERSISTENT SPREADING CONTRAILS

3 TYPES OF CONTRAILS

SHORT LIVED CONTRAILS

– if the air is somewhat moist, a contrail will form right behind the airplane and make a bright white line that lasts for a short while.

PERSISTENT NON-SPREADING CONTRAILS

if the air is very moist, a contrail will form behind an airplane and stay in the sky for a long time. This type of contrail will stay in the sky long after the airplane has flown out of sight, can last for a few minutes or longer than a day, and it keeps its shape of a thin line.

PERSISTENT SPREADING CONTRAILS

these contrails form when a persistent contrail spreads out. They grow wider and fuzzier as time passes. Sometimes contrails will take on the characteristics of a natural cirrus cloud and no longer look like contrails, so they become human – made clouds.