2. Systems science An approach to hydrological studies in this unit

3. PrecipitationEvapotranspiration Pond Storage Overland Flow Throughfall Interception Interception Storage Infiltration Soil moisture storage Interflow Throughflow Groundwater recharge Groundwater storage Baseflow Return flow Channel storage Runoff Groundwater discharge

4. Koeppen classification BoM => Climate Services => Climate data online => Climate maps

5. Definition: –All forms of moisture being released from the atmosphere Snow, hail, sleet, drizzle, rainfall Rainfall primary mechanism for Australia/Jordan ClassDefinition: according to the UKMO (UK Meteo. office) RainLiquid water droplets – 0.5-0.7mm diameter DrizzleRain, but with droplets <0.5 SleetFrozen raindrops (snow and rain) SnowIce crystals joined together HailBalls of ice – 5-125mm in diameter Precipitation

6. Satellite images Precipitation BoM => Satellite => Full disk

7. 0 30 20 10 20 10 30 40 Air Temperature o C Amount of water vapour cm 3 /m 3 Saturation level Precipitation

8. 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

9. What controls where rain falls? Highly variable distribution –At all scales – country to backyard variation Altitude, aspect, slope, ocean temperature Cooler airWeather directionMeasurement, angle of rain

10. 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 (m 3 ) = 1000 litres One millimetre depth over one hectare = 10m 3 10cm depth over one hectare = 1000m 3 = 1Megalitre (ML) Rainfall and evaporation are also by rate (mm/hour, mm/day, mm/year)

11. Measuring precipitation

12. Standard rain gauge Pluviometer World Meteorological Organisation (WMO)

15. Tipping Bucket Rain Gauge

16. Data logger connects to computer and www or phone line or telemetry Automated temporal measurement

17. Automated recording of several measurements Phone or telemetry reading

18. Optical rain gauge Measures intensity by rainfall passing through a light beam

19. Radar Temporal distribution - Intensity - Duration Spatial distribution - Aerial - Virga? or fall? - Fire? Insects?

21. Evaporation Pan

22. 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

25. Transpiration Type and age of plant: Leaf area Leaf orientation Leaf surface Stomata Environment: Humidity Temperature Light intensity Wind Soil moisture

26. Measuring eddies Ventilated chamber Sap flow Porometer

27. Portable, widely used in horticultural industry and reasonably easily calibrated

28. Sap flow measurement Uses thermocouple device Measures sap flow in both directions Xylem (flows up) Phloem (flows down) Widely used in forestry industry

32. Interception, Interception storage, Stem flow, Throughfall (the hard ones to accurately measure)

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

34. Lysimeters

35. Direct measurements Weight changes Deep drainage

36. E T = S i + P R + I R –S f - D E E T = Evapotranspiration in a given time period S i = Initial soil water volume S f = Final soil water volume P R = Precipitation into lysimeter I R = Irrigation water into lysimeter D E = Drainage of water from lysimeter I – O = ΔS Hydrologic equation