MIDTERM Flashcards
study of the occurrence, movement,
distribution, and quality of water throughout the earth.
Hydrology
Branch of physical geography which is concerned
with the origin, distribution, and properties of the
waters of the earth.
HYDROLOGY
study the physical processes in the
atmosphere, specifically weather and climate.
METREOLOGY
Meteorological approach to
hydrologic problem
HYDROMETEOROLOGY
Importance of Hydrology
(1) Estimating reservoir storage capacity
(2) Planning water resources projects, the peak discharge
and its volume of flood.
(3) Estimating the impact of watershed management on the
quantity and quality of the surface and the groundwater
resources.
(4) Planning an integrated water resources development
master plan for a basin.
(5) Trans-boundary river water allocation problems, and
(6) Delineation of probable flood levels to plan protection
of settlements and projects from flooding or to promote
better zoning.
study of the transfer of water and
energy between land and water body surfaces and the
lower atmosphere
HYDROMETREOLOGY
study of the hydrologic processes
that operate at or near the Earth’s surface.
Rivers, dams, lakes
Issues on eroding soils and streams due to surface
flow
Surface Hydrology
“geohydrology”, study of the presence
and movement of water in aquifers and shallow porous
media.
Hydrogeology
drain basin management;
covers water storage and flood protection.
Watershed Management –
chemistry of water in rivers and lakes,
both of pollutants and natural solutes.
Water Quality
– study of chemical characteristics of
water.
Chemical Hydrology
Study of ecological processes in the
hydrologic cycle.
Ecohydrology –
Adaptation of information technology
to hydrology and water resources applications
Hydroinformatics
– study of the isotopic signatures of
water.
Isotope Hydrology
Continues chain of movement and
interchange of water between oceans, atmosphere and
land surface and below the land surface.
Hydrologic Cycle –
Four Basic Components
Evaporation and
transpiration
Precipitation
Groundwater
Runoff
water vapor is discharged to the
atmosphere as a result of —— from the soil.
. Evaporation –
– process by which water is changed from
vapor to liquid.
Condensation
discharge of water, in liquid or solid state,
out of the atmosphere, generally upon a land or water
surface.
. Precipitation –
release of water from plant leaves. Every
day, an actively growing plant transpires 5 to 10 times as
much water as it can hold at once. 10% of the moisture
found in the atmosphere is released by plants.
Transpiration –
Tinier dust, salt, or smoke particles in
which water droplets must condense with for precipitation
to happen.
Condensation Nuclei –
is precipitation trapped by vegetation
instead of falling directly onto the soil.
Interception –
when the rainfall is heavy and the soil saturated,
water flows over the land called _____
Runoff –
– Precipitation runoff which travels
over the soil surface to the nearest stream channel.
Surface Runoff
water getting infiltrate into
previous soil mass making it ways towards the rivers and
lakes
Subsurface Runoff –
movement of water in a natural channel, such
as river
Streamflow –
downward movement of water from the land
surface into soil or porous rock
Infiltration –
downward movement of groundwater
through cracks, joints and pores in soil and rocks until it
reaches the water table where it becomes groundwater.
Percolation
lateral movement of groundwater.
Seepage
movement of water out of the
ground.
Groundwater Discharge
water existing for long
periods below the
Earth’s surface.
Groundwater storage –
level at
which water stands in a
shallow well.
Water Table –
water fills all the spaces in the
rock.
Zone of Saturation –
water does not fully saturate the
pores.
Zone of Aeration –
divides one zone from the other
Water Table –
geologic formation which contains water and
transmits it at a rate sufficient to be economically
developed for pumping;
Aquifer –
occurs in two ways:
When precipitation exceeds the infiltration rate
When the soil is saturated
Overland flow
water flowing through the soil in natural pipes
percolines (lines of concentrated water flow between
horizons).
Throughflow –
movement of water within the zone of aeration.
BASEFLOW
flow of water within the zone of saturation
INTERFLOW
structure or volume in space enclosed
by a boundary that accepts water and other inputs,
operates on them internally and produces them as output.
Hydrologic System –
Six (6) Major Components of Hydrologic Cycle
- Precipitation
- Infiltration
- Evaporation
- Transpiration
- Surface Runoff
- Groundwater
part of the atmospheric moisture that falls
back on the earth surface.
Precipitation –
Brought about by one or more of the following reasons:
- Adiabatic Cooling
- Mixing of air masses if varying temperatures
- Radiation Cooling
- Contact Cooling
3 Ways to Form Precipitation
3 Ways to Form Precipitation
1. Convection
2. Cyclonic
3. Orographic
particles of
ocean salt, products of combustion and oxides of nitrogen
with 0.1 to 10 µm in diameter.
Condensation or Sublimation (Freezing) Nuclei –
– fusion of water droplets as a result
of their coming in contact through air movement and
gravitational pull
Coalescence process
vapor pressure around water droplets
is higher than that over ice crystals, resulting in the
condensation of moisture over ice crystals.
Ice Crystals process –
tiny liquid water
droplets, 0.1 to 0.5 mm Φ.
Drizzle or Mist –
.liquid water drops > 0.5 mm Φ.
. Rain –
refers to amount of liquid
precipitation
RAINFALL
Ice coating, generally
clear and smooth, formed on
exposed surfaces by the freezing
of super cooled water deposited
by rain or drizzle. Specific gravity…
GLAZE - ≈ 0.8 to 0.9
white, opaque deposit of
ice granules separated by
trapped air and formed by rapid
freezing of supercooled water
dropsSpecific gravity
RIME - ≈ 0.2 to 0.3
composed of ice crystals,
chiefly in complex, branched
hexagonal form, and often
agglomerated into snowflakes
(may reach 100 mm Φ).
Average specific gravity
≈ 0.1
SNOW
balls of ice produced in
convective clouds
HAIL
– spheroidal, conical or
irregular in shape (specific gravity
Hailstones ≈
0.8)
transparent, globular, solid grains
of ice formed by the freezing or raindrops
or refreezing of melted ice crystals as it falls
in a layer of subfreezing air near the
surface
SLEET
amounts and intensity of rainfall
are important since most estimates of runoff rates are
based on rainfall data
Measurement of Rainfall –
average rainfall depth
that falls per time increment.
Rainfall Intensity (usually in mm/hr) –
high intensity storms generally last for short period
of time.
Duration –
very intense storms are not necessarily more
frequent the infrequent combination of high intensity and
long duration gives larger total amount of rainfall.
Frequency –
probabilistic analysis of
hydrologic processes deals with the estimation of the
chance or likelihood of occurrence of a given event by
determining the frequency curve of best fit to samples of
hydrologic data
Hydrologic Frequency Analysis –
– it realtes the
magnitude of a variable to its frequency of occurrence.
Frequency Curves
a tool that
characterizes an area’s rainfall pattern.
Intensity-Duration-Frequency (IDF) Curve –
most hydrologic and agronomic
problems require the estimation of the average rainfall
depth over an area such as a watershed and cropped
area
Areal Precipitation –
the simplest of the area averaging
methods.
Arithmetic Averages –
assumes that the rainfall in an area
may be taken as similar to that recorded in the nearest
gaging station
THISSEN METHOD
the rainfall depths recorded in all the
stations in and around an area of interest are plotted on a
map of desirable scale.
Isohyetal Method –
consist of the root zone
(soil water), intermediate zone and transition layer to the
zone of saturation.
Zone of Aeration (Vadose zone) –
– all voids are filled with
water.
Zone of Saturation (Phreatic zone)
divides the two major subsurface
zones
Water Table –
local saturated zones
above impervious layer; of limited extent.
Perched Groundwater –
contains water and transmits it at rate sufficient to
be economically develop for pumping.
Aquifer –
does not readily yield water, but may serve as a
storage unit for groundwater (e.g. sandy clay)
Aquitard –
geologic formation which contains water but
is not capable of transmitting (e.g. clay)
Aquiclude –
has no interconnected openings and cannot
hold nor transmit water.
Aquifuge –
has water table serving as upper
surface of the zone of saturation.
Unconfined Aquifer –
the water level in these
wells indicates the position of the water table
in the surrounding aquifer
Water table wells –
ground water is confined by
relatively impermeable layer
Confined or Artesian Aquifer –
the upper confining layer is leaky
or semi-permeable.
Semi-Confined Aquifer –
wells drilled into confined aquifers, water
rises to the piezometric level.
Artesian Wells –
wells drilled into confined aquifers wherein
the piezometric level is above ground.
Flowing Wells –
measure of the water retained by
the soil formation against the force of gravity
Specific Retention, Sr –
the water that can be extracted by
gravity flow
Specific Yield, Sy –
the fraction of the porosity of an aquifer
Specific Yield, Sy –
those with uniform hydraulic
conductivity
isotropic Aquifers –
those with varying k values.
Anisotropic Aquifers –
rate of flow of water at the
prevailing water temperature through a vertical strip of the
aquifer one foot wide extending the full saturated thickness
of the aquifer under a hydraulic gradient of 100%.
Coefficient of Transmissibility –
the rate at which water of the prevailing
kinematic viscosity is transmitted through unit width of the
aquifer under a unit hydraulic gradient.
Transmissibility, T –
the volume of
water released or added per unit area of aquifer per unit
drop or rise in head or pressure.
Storage Coefficient or Storativity, Sc –
