PRELIM Flashcards
means the science of water. It is the science that deals with the occurrence, circuation and distribution of water of the earth and earth’s atmosphere.
Hydrology
describes the continuous movement of water on, above and below the earth surface.
water cycle, also known as the hydrologic cycle
rives the water cycle, radiates solar energy on the oceans and land.
The sun
can sublimate directly into water vapor.
Ice and snow
water transpired from plants and evaporated from the soil.
Evapotranspiration
Rising air currents take the vapor up into the atmosphere where cooler temperatures cause it to ________ into clouds.
Condense
______________ move clouds around the globe, cloud particles collide, grow, and fall out of the sky as ____________
Air currents, Precipitation
Condensed water vapor that falls to the earth surface. Mostly occurs as rain but also includes snow, hail, fog drip. etc.
Precipitation
Variety of ways by which water moves across the land. As it flows, water may infiltrate into the ground, evaporate into the air, and become stored in lakes or reservoir, or be extracted for agricultural uses or other human uses.
Runoff
Flow of water from ground surface into the ground. Once infiltrated, water becomes soil moisture or groundwater.
Infiltration
Flow of water underground, it can return into the surface or seep into the ocean.
Subsurface flow
Transformation of water from liquid to gas, it moves from the ground or bodies of water into the overlying atmosphere.
Evaporation
is a very light, usually uniform, precipitation consisting of numerous minute droplets with diameters in excess of 0.1 mm but smaller than 0.5 mm.
Drizzle
precipitation consisting of water drops larger than 0.5 mm. It can be classified as light rain when the intensity is smaller than 2.5 mm/hr, moderate when it is between 2.5 and 7.5 mm/hr, and heavy when it exceeds 7.5 mm/hr.
Rain
precipitation in the form mainly of branched hexagonal or star-like ice crystals, resulting from direct reverse sublimation of the atmospheric water vapor; snow particles can reach the ground as single crystals, but more often than not they do so after agglomerating as snowflakes. These flakes tend to be larger at temperatures close to freezing.
Snow
(North American usage) is precipitation consisting of fairly transparent pellets or grains of ice, formed as a result of the passage of raindrops through a layer of colder air near the ground. In British usage the word sleet refers to precipitation consisting of melting snow or a mixture of snow and rain.
Sleet
is ice deposited by drizzle or rain on cold surfaces.
Glaze or Freezing rain
(also called granular snow or graupel) are a form of precipitation consisting of white, opaque, small grains with diameters between roughly 0.5 and 5 mm.
Snow pellets
consists of balls or irregular chunks of ice with diameters between 5 and 50 mm, or even larger. These lumps of ice can be transparent or they can consist of concentric layers of clear and opaque ice; such layered structure is the result of the alternating rising and falling movements during the hail formation. Hail usually falls during violent and prolonged convective storms under above-freezing temperature conditions near the ground; it can cause severe damage.
Hail
consists of moisture in the form of liquid drops on the ground surface and on the vegetation and other surface elements, as a result of direct condensation of atmospheric water vapor.
Dew
Rainfall Characteristics
Depth, Intensity, Duration
defined as the total amount of rain in an area.
Depth
period of time during which continuous rain is observed, or occurs, at a given point or within a given area.
Duration
is defined as the ratio of the total amount of rain (rainfall depth) falling during a given period to the duration of the period It is expressed in depth units per unit time, usually as mm per hour (mm/h).
Intensity
a meteorological instrument designed to measure precipitation in its liquid form in a specific area over a predetermined period of time.
Rain gauge
Also known as the standard rain gauge, the graduated cylinder rain gauge is a simple, measured glass cylinder. It is used by all professional weather services in manned stations and is the most accurate way of directly measuring rainfall. The water gets collected by a cylindrical funnel, from where it flows directly into the graduated cylinder, or captured by a container and then poured measured cylinder.
Graduated cylinder rain gauge
an automated rain meter that uses a “tipping bucket” mechanism to measure rainfall. It is used by professional weathers services’ remote weather stations, and is also popular and widely used in home weather stations. Like a standard rain gauge, it uses a collector funnel with a narrow pipe at the bottom to capture rainfall. From the pipe, the water drops onto a finely-balanced seesaw device with small buckets on each side.
Tipping bucket rain gauge
consists of receiving bucket mounted on a weighing device, usually a mechanical mechanism such as a spring. The rain accumulates in the container, and the increased weight compresses the springs. The amount of compression gets measured and used to calculate the weight of the water. The measurement can be recorded manually with a pen on a drum, or electronically with a data-logger, and send to the base weather station via landline or wireless connection.
weighing precipitation gauge
consists of a laser/infrared diode and photosensitive sensor situated in enclosed spaces on opposites sides and below a row of funnels that receive rainfall. Each funnel has a small opening at the bottom through which raindrop forms when enough precipitation accumulates inside the container. Once the waterdrop grows large enough, it falls from the funnel and though the space between the laser diode and photosensor.
Optical rain gauge
Also known as hydrophones, are used to measure the rainfall over large bodies of water like dams, lakes, and the ocean. The device itself gets place underneath the water’s surface. The hydrophone can sense and measure the impact of the raindrops, hitting the surface of the water.
Acoustic rain gauge
Can be done manually or by using GIS application.
Delineation of watershed
Also known as basin, river basin, or watershed. It is an extent of land where water from rain or snow melt drains downhill into a body of water such as river, lake, reservoir, etc.
Catchment area
The sun is the driving force for the hydrological cycle. Precipitation comes from water vapor generated by the solar radiation from land and ocean.
Atmospheric water
may be considered as falling bodies that subject to gravitational, buoyancy and air resistance effects.
Rain drop
are used collectively to estimates areal variability of rain and snow.
Point Precipitation Data
It assumes that at any point in a catchment, the rainfall is the same as that at the nearest rain gauges so the depth recorded at a given gauges is applied out to a distance halfway to the next gauge in any direction. Ans.
Theissen Polygon Method
The process of infiltration has been widely studied and represents an important mechanism for the movement of water into the soil under gravity and capillarity forces.
Infiltration
subtracted from a precipitation event in order to determine the net volume of rainfall, or rainfall excess, which is equivalent to the direct runoff from a watershed area.
Infiltration volume
Factors affecting infiltration
-precipitation
-soil types
-water content of the soil
-vegetation cover or land cover
-ground slope
determined from the size distribution of individual particles in a soil sample. Soil particles smaller than 2 mm are divided into three soil categories; sand silt and clay.
Soil texture
________________ of soil having the greatest effect on infiltration are bulk density, organic matter, and clay type. These properties are closely related to soil structure and soil surface area.
morphological properties
_______________________ of the soil are important because they affect the integrity of the soil aggregates (group of soil particles bound together). Chemical soil properties should be considered when they are outside normal ranges. Also, chemistry of the infiltrating water can have an effect on infiltration.
chemical properties
The higher the water content, the smaller the infiltration rate.
Soil water content
describes the soil’s ability to store and release water and is defined as the relationship between the soil water content and the soil suction.
Water retention characteristic
is the ability of soil to transmit water and depends upon both the properties of soil and the fluid. Total porosity, pore size distribution, and pore continuity are the important soil characteristics affecting hydraulic conductivity.
Hydraulic conductivity
the factors that affect the movement of water through the air-soil interface.
Surface factors
These are materials that protect soil surface. Lack of cover, or bare soil, is associated with the formation of a surface crust. The impact of raindrops can break down surface soil structure and cause the movement of soil fines into surface or near surface porosity.
Surface Cover
can be man-made or natural. Man-made configurations result from various kinds of tillage.
Surface configuration
results from interception and/or depressions. Interception is caused by vegetation or other types of surface cover.
Surface storage
is a device used to measure the rate of water infiltration into soil or other porous media. Commonly used _________________are single ring or double ring _____________________
Infiltrometer
has no disturbance to soil, close to true rainfall impact and much costly compared to infiltrometer.
Artificial Rain simulator
