PrecipitationEvapotranspiration

Pond Storage

Overland Flow

Throughfall

Interception

Interception Storage

Infiltration

Soil moisture storage Interflow

Throughflow

Groundwater recharge

Groundwater storage Baseflow

Return flow

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Systems science

An approach to hydrological studies in this unit

PrecipitationEvapotranspiration

Pond Storage

Overland Flow

Interception

Interception Storage

Infiltration

Soil moisture storage Interflow

Throughflow

Groundwater recharge

Groundwater storage Baseflow

Return flow

Cha

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Run

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Koeppen classificationBoM => Climate Services => Climate data online => Climate maps

• Definition: – All forms of moisture being released from the

atmosphere• Snow, hail, sleet, drizzle, rainfall

• Rainfall primary mechanism for Australia/Jordan

Class Definition: according to the UKMO (UK Meteo. office)

Rain Liquid water droplets – 0.5-0.7mm diameter

Drizzle Rain, but with droplets <0.5

Sleet Frozen raindrops (snow and rain)

Snow Ice crystals joined together

Hail Balls of ice – 5-125mm in diameter

Precipitation

Satellite images

PrecipitationBoM => Satellite => Full disk

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Air Temperature oC

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Saturation level

Precipitation

Cloud formation

Convection

Frontal

Orographic

Warm air rises from warm land mass

Warm air rises over cold front

Warm air rises over topographic high

Precipitation

What controls where rain falls?

• Highly variable distribution– At all scales – country to backyard variation

• Altitude, aspect, slope, ocean temperature

Cooler air Weather direction Measurement, angle of rain

About Units...Some hydrologic processes are measured by depth and others by volume.

Rainfall and evaporation are measured by depth (usually millimetres)

One cubic metre (m3) = 1000 litresOne millimetre depth over one hectare = 10m3 10cm depth over one hectare = 1000m3 = 1Megalitre (ML)

Rainfall and evaporation are also by rate (mm/hour, mm/day, mm/year)

Measuring precipitation

Measuring precipitation

Standard rain gauge

Pluviometer

World Meteorological Organisation(WMO)

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Apollo Bay & Weeaproinah 1900 - 2000

TippingBucket

RainGauge

Data loggerconnects tocomputer and www or phone line or telemetry

Automated temporal measurement

Automated recordingof several measurements

Phone or telemetry reading

Optical rain gauge

Measures intensityby rainfall passing

through a light beam

Radar

Temporal distribution- Intensity- Duration

Spatial distribution- Aerial- Virga? or fall?- Fire? Insects?

Evaporation Pan

Pan reading over 24 hours (minus rainfall input)

ET = Pan reading x Pan factor

Pan factor ~ 0.5 to 0.8 usually ~ 0.75

Pan Evaporation conversion to Evapotranspiration

Transpiration

Type and age of plant:• Leaf area• Leaf orientation• Leaf surface• Stomata

Environment: • Humidity• Temperature• Light intensity• Wind• Soil moisture

Measuringeddies

Ventilatedchamber

Sapflow

Porometer

PorometerPortable, widely used in horticultural industry and reasonably easily calibrated

Sap flow measurementUses thermocouple deviceMeasures sap flow in both directionsXylem (flows up)Phloem (flows down)Widely used in forestry industry

Interception, Interception storage, Stem flow, Throughfall

(the hard ones to accurately measure)

Stem flow is measured using interceptor drains around the trunk, Throughfall is measured using rain gauges under the tree canopy

Lysimeters

Direct measurementsWeight changesDeep drainage

ET = Si + PR + IR –Sf - DE

ET = Evapotranspiration in a given time periodSi = Initial soil water volumeSf = Final soil water volumePR = Precipitation into lysimeterIR = Irrigation water into lysimeterDE = Drainage of water from lysimeter

I – O = ΔSHydrologic equation