Meteorology Precipitation Evaporation Transpiration Evapotranspiration

1. Meteorology Precipitation Evaporation Transpiration Evapotranspiration

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

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

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

5. Precipitation • Definition: • All forms of moisture being released from the atmosphere • Snow, hail, sleet, drizzle, rainfall • Rainfall primary mechanism for Australia/Jordan

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

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

8. Cloud formation Precipitation Convection Warm air rises from warm land mass Frontal Warm air rises over cold front Orographic Warm air rises over topographic high

9. 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

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 (m3) = 1000 litres One 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)

11. Measuring precipitation

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

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 Evaporation conversion to Evapotranspiration Pan reading over 24 hours (minus rainfall input) ET = Pan reading x Pan factor Pan factor ~ 0.5 to 0.8 usually ~ 0.75

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 Porometer Sap flow Ventilated chamber

27. Porometer 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. ET = Si + PR + IR –Sf - DE ET = Evapotranspiration in a given time period Si = Initial soil water volume Sf = Final soil water volume PR = Precipitation into lysimeter IR = Irrigation water into lysimeter DE = Drainage of water from lysimeter Hydrologic equation I – O = ΔS