Irrigation and Hydrology – Key Vocabulary

A comprehensive set of 100 vocabulary flashcards covering fundamental concepts, devices, processes, and structures discussed in the lecture on irrigation and hydrology.

Irrigation

Artificial application of water to soil for raising crops.

Irrigation Engineering

Science of planning, designing, and managing economical water-supply systems for agriculture.

Flow Irrigation

Irrigation where water reaches fields by gravity from a source at higher elevation.

Lift Irrigation

Irrigation that requires pumping water to a higher level before distribution.

Perennial Irrigation

Continuous, controlled supply of water to crops throughout their growth period.

Inundation Irrigation

Irrigation by deep flooding and saturation of land, water later drained before planting.

Direct Irrigation

Diversion of river water directly to canals without intermediate storage.

Storage Irrigation

Use of a dam or weir to store excess flow in a reservoir for later irrigation.

Combined Storage-Diversion Scheme

System storing water upstream for power or regulation, then diverting flow downstream by a pick-up weir.

Rajasthan Canal

Major canal conveying water to arid regions of Rajasthan with <200 mm annual rainfall.

Kharif Crops

Monsoon-season crops grown during periods of natural rainfall.

Rabi Crops

Winter-season crops requiring supplemental irrigation in India.

Perennial Crops

Crops like sugarcane needing water supply year-round.

Controlled Water Supply

Distribution system delivering optimal water amounts at desired times to increase yield.

Increase in Food Production

Primary benefit of irrigation achieved through timely, adequate watering.

Famine Protection

Role of irrigation projects in providing employment and water security during droughts.

Cash Crops

High-value commercial crops made possible by reliable irrigation (e.g., cotton, tobacco).

Mixed Cropping Elimination

Shift from mixed to single-crop fields when irrigation reduces weather risk.

Hydro-Electric Power Generation

Electricity produced from river valley and canal falls integrated with irrigation schemes.

Inland Navigation

Use of large irrigation canals as waterways for transport of goods.

Canal Plantation

Tree growth along damp canal strips, adding timber value and reducing erosion.

Water-Logging

Raising of groundwater table by over-irrigation, saturating root zones.

Breeding Places for Mosquitoes

Stagnant water from leaks or excess irrigation encouraging malaria vectors.

Damp Climate Effect

Increase in local humidity and coldness induced by extensive irrigation in already damp areas.

Non-automatic Rain-Gauge

Device recording total rainfall only when manually measured; no time history.

Symon's Rain-Gauge

Standard 127 mm non-recording gauge used at Indian meteorological stations.

Automatic Rain-Gauge

Recording instrument producing a continuous rainfall trace or digital pulses.

Weighing Bucket Rain-Gauge

Recorder where rainfall weight moves a pen on a chart, showing intensity.

Tipping Bucket Rain-Gauge

Gauge with dual buckets tipping after fixed volume; each tip sends an electrical impulse.

Float Type Rain-Gauge

Recorder where rising water lifts a float; a syphon empties the chamber after full.

Hydrology

Science of occurrence, distribution, and movement of water on and below Earth’s surface and in the atmosphere.

Hydrologic Cycle

Continuous circulation of water between atmosphere, land, and oceans through evaporation, precipitation, and runoff.

Evaporation

Change of water from liquid to vapor below boiling point at a free surface.

Transpiration

Loss of water vapor from plant leaves through stomata.

Precipitation

Moisture falling from atmosphere to Earth as rain, snow, hail, etc.

Runoff

Portion of precipitation that flows over or through the land to streams and rivers.

Surface Runoff

Water moving across the ground surface to the nearest channel.

Sub-surface Runoff (Interflow)

Lateral movement of infiltrated water through upper soil layers to streams.

Groundwater Flow (Base Flow)

Stream discharge sustained by seepage from the saturated zone.

Infiltration

Process by which water enters the soil surface.

Saturation Vapour Pressure

Vapour pressure in air when it is fully saturated at a given temperature.

Dalton’s Law of Evaporation

Evaporation rate proportional to difference between saturation vapour pressure at water surface and actual vapour pressure of air.

Vapour Pressure Deficit

Difference eₛ − eₐ controlling potential evaporation rate.

Catchment Area

Land area from which precipitation drains to a common outlet.

Drainage Basin

Synonym for catchment; region contributing flow to a river system.

Watershed Ridge Line

Highest contour bounding a basin and separating adjacent drainage areas.

Stream

Natural channel conveying runoff from a basin to a larger water body.

Overland Flow

Sheet flow of water across land before concentrating into channels.

Drainage Density

Total length of streams divided by basin area.

Basin Recharge

Portion of rainfall retained as interception, depression storage, or soil moisture.

Depression Storage

Water held in small land surface depressions after rainfall.

Fan-Shaped Catchment

Basin with tributaries of similar length, producing synchronized peak flow.

Fern Leaf Catchment

Long narrow basin with hierarchic tributaries, producing spread-out runoff.

Effluent Stream

Channel receiving water from groundwater when it lies below water table.

Influent Stream

Channel losing water to the ground when water table lies below bed level.

Evaporation Pan

Instrument measuring open-water evaporation, basis for lake evaporative estimates.

IS:5973-1970 Pan

Indian standard class-A pan (1.22 m diameter) used for evaporation measurement.

Condensation

Change of water vapor to liquid droplets forming clouds.

Liquid Precipitation

Rainfall occurring as water droplets.

Frozen Precipitation

Moisture falling as snow, sleet, hail, or freezing rain.

Snow

Crystalline frozen precipitation forming flakes.

Sleet

Frozen raindrops or ice pellets formed in atmosphere.

Hail

Hard, rounded ice particles produced in thunderstorms.

Freezing Rain

Super-cooled raindrops that freeze on contact with surfaces.

Humidity

Amount of water vapor present in air.

Vapour Pressure

Partial pressure exerted by water vapor in the atmosphere.

Saturation Deficit

Shortfall of actual vapour pressure from saturation value at a given temperature.

Cloud

Visible mass of condensed water vapor suspended in atmosphere.

Solar Radiation

Sun’s energy driving evaporation and climatic processes.

Atmospheric Pressure

Force per unit area exerted by air column, influencing evaporation.

Wind Velocity

Speed of air movement affecting evaporation and rainfall measurement.

Evapo-transpiration

Combined water loss from soil evaporation and plant transpiration.

Interception

Rainfall captured by vegetation before reaching ground.

Percolation

Downward movement of water through soil to recharge groundwater.

Groundwater Table

Upper surface of saturated zone within the soil or rock mass.

Water Table Rise

Upward movement of groundwater level due to excess irrigation or rainfall.

Water Power Engineering

Branch of engineering dealing with hydroelectric energy harnessed from water.

River Canal Irrigation

Irrigation supplied by canals diverting flow directly from rivers.

Storage Weir

Overflow structure across a river forming a small reservoir for irrigation supply.

Diversion Weir

Low barrier that raises river water level just enough to divert flow into canals.

Barrage

Type of diversion weir with adjustable gates controlling river flow and canal supply.

Head Regulator

Gate structure at canal head controlling discharge from river or reservoir.

Cross Drainage Work

Structure carrying a canal over or under a natural drain or stream.

Aqueduct

Canal carried over a drainage channel on a bridge-like structure.

Superpassage

Natural drain carried over a canal in an inverted syphon arrangement.

Syphon Aqueduct

Aqueduct where the drain passes below canal water level through a syphon.

Canal Syphon

Canal carried under a drain using a pressure conduit.

Tail Escape

Outlet releasing surplus canal water back to a natural drain at channel end.

Tail Cluster

Group of fields or outlets located at the downstream end of a canal distribution system.

Marginal Bund

Embankment along river or canal edge preventing flood spill into adjacent land.

Pick-up Weir

Low downstream weir re-diverting water released from an upstream powerhouse.

Kota Dam

Storage structure on Chambal River forming part of a storage-cum-diversion scheme.

Kota Barrage

Downstream diversion structure on Chambal River supplementing Kota Dam operation.

Factors Affecting Runoff

Precipitation features, basin shape, topography, geology, meteorology, surface cover, and storage.

Meteorological Data

Information on precipitation, humidity, temperature, radiation, and wind for hydrologic analysis.

Measuring Glass (Rain-Gauge)

Graduated cylinder used to transfer collected rainfall and read depth to 0.1 mm.

Evaporation Loss Factors

Variables like area, depth, humidity, wind, temperature, and water quality influencing evaporation.

Period of Empiricism (Hydrology)

Era (~1850-1925 in India) focusing on empirical formulas and curves for water studies.

Period of Theorization

Hydrology phase (post-1950) emphasizing theoretical analysis and modeling of water processes.