Hydrology

treatments of waters of the earth, occurrence, circulation and physical properties, their reaction to environment

Hydrology

atmospheric phenomenon, produce atmosphere

Meteorology

means and extremes of weather phenomenon

Climatology

agency concerned with weather conditions

PAG-ASA

PAG-ASA

Philippine Atmospheric Geophysical and Astronomical Services Administration

Allied Sciences

Meteorology and Climatology, Physical Geography, Agronomy and Forestry, Geology and Soil Sciences, Oceanography and Hydraulics

Hydrologic Features

Rain, Snow, Evaporation, Heat, Cold and Wind

It is affected materially by the physical features of the earth’s surface

Hydrology - under of Physical Geography

Obtained of mountains, steep slopes

Geography

Distribution of vegetables cover in locality

Hydrology - under of Agronomy and Forestry

ability of the soil cover to infiltrate water

Vegetation

composition of earth’s crust

Geology and Soil Sciences

nature’s reservoirs

Oceanography

overlap, matter of opinion

under of hydraulics - purely hydrology, and purely hydraulic

steady flow of water, transmission of flood waves

uner of hydraulics - hydraulics principles

The most important use of Hydrology in …. is in the structural and hydraulic design of water control structures

Water Resources Engineering

Unending circulation of water

Hydrologic Cycle

liquid to vapor state

Evaporation

bringing

Lifting

vapor to liquid state

Condensation

fall of moisture or water

Precipitation

suspension of the precipitation by vegetation

Interception

due to the action of gravity

run-off

downward movement of water

percolation

underground movement of water

infiltration

moisture is released into the air

transpiration

accumulation of water

Storage

expressed as the depth of liquid water

precipitation

run offs to the streams, cause of most floods

liquid precipitation

remains where it falls for a long time before it melts

frozen precipitation

over 0.5 mm

rain

under 0.5 mm

drizzle

condensation of water vapor

dew

tiny drops of water that form on cool surfaces at night

dew

water droplets so small, restricts visibility

fog

adhere and coalesce with other droplets that will form a large drop to fall on the ground

fog drips

drizzle or rain frozen as it comes in contact

glaze

frozen raindrops cooled to ice stage

sleet

hexagonal crystals

snow

form of a number of ice crystals fused together

snow flakes

upward movement of the air; spotty; formation of most thunderstorms

convective precipitation

mountain barrier

orographic precipitation

another term for orographic precipitation

mountain type precipitation

depressions or cyclones; LPA

cyclonic precipitation

gas

water vapor

total moisture

1/2

Altitude

2000 meters

retain a large amount of moisture

warm air

air is saturated

dew point

wetness of the air

relative humidity

precipitation disposal depents on the amount, intensity, occurrence

under of meteorological conditions - precipitation

being the minimum during winter and maximum during summer

under of meteorological conditions - temperature

more less inversely proportional to humidity

under of meteorological conditions - relative humidity

affects the amount of evaporation and interception losses

under of meteorological conditions - wind

area-tributary

drainage area / river basin / catchment / watershed

slopes of the land surface

under of drainage-area characteristics - topography

character of the surface and subsurface conditions

under of drainage-area characteristics - geology

whether it is bare, vegetated or cultivated

under of drainage-area characteristics - conditions of surface area

water losses below the ground surface

Soil Evaporation

another method wherein water is lost from the soil

transpiration

building of plant tissues

transpiration

transpiration rate is determined by

potometer / phytometer

percentage of interception losses is highest, nearly …. in light showers and about …. under heavy rain

100%, 25%

interception is measured by

interceptometers

Hydrologic Cycle

Evaporation, Lifting, Condensation, Precipitation, Interception, Run-off, Percolation, Infiltration, Transpiration, Storage

Forms of Precipitation

Mainly Two Forms: Liquid Precipitation, and Frozen Precipitation
Others: Rain, Drizzle, Dew, Fog, Glaze, Sleet, Snow, Snow Flakes

Kinds of Precipitation / Lifting

Convective Precipitation, Orographic Precipitation, Cyclonic Precipitation

Precipitation that reaches the surface of the earth is disposed off by:

run-off, evaporation, percolation

factors that affect the disposal of precipitation

meteorological conditions, drainage-area characteristics, storage characteristics

meteorological conditions

precipitation, temperature, relative humidity, wind

drainage-area characteristics

topography, size and shape of catchment, geology, conditions of surface area

Evaporation is affected by

vapor pressure difference, temperature of the air and water, relative humidity, atmospheric pressure, wind velocity, water depth, water surface area, water quality

Soil Evaporation depends upon the ff.:

land surface condition, soil & subsoil characteristics, temperature, relative humidity, wind velocity, and slope of the ground.