1 / 67

Measuring and Modeling Transpiration, or What the Flux is Hydrology? ChEAS Workshop

Measuring and Modeling Transpiration, or What the Flux is Hydrology? ChEAS Workshop. Scott Mackay UW-Madison. Outline. (A) Basic Hydrologic Concepts A.1 Water Resources and Global Terrestrial Ecosystems A.2 Hydrologic budgets and conservation

shanon
Download Presentation

Measuring and Modeling Transpiration, or What the Flux is Hydrology? ChEAS Workshop

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Measuring and Modeling Transpiration,or What the Flux is Hydrology?ChEAS Workshop Scott Mackay UW-Madison Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  2. Outline (A) Basic Hydrologic Concepts A.1 Water Resources and Global Terrestrial Ecosystems A.2 Hydrologic budgets and conservation A.3 Evapotranspiration as a residual: the traditional hydrologic approach (B) Transpiration B.1 Direct measurements of transpiration B.2 Indirect measurements of transpiration B.3 Sapflux instrumentation and flux measurements in N. Wisconsin (C) Water Flux Modeling C.4 Groundwater / surface water interactions C.2 Incorporating spatial variation in water fluxes C.3 Incorporating physiology C.4 Results from N. Wisconsin (D) Future Directions? Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  3. Future Directions? • Suggested question: • How does landscape fragmentation affect transpiration and carbon flux rates? • Your mission: • Develop a 1 (2 max) page micro proposal that addresses the above question or one of your choosing; • Your proposal should state questions or hypotheses, objectives, how you would conduct the work, and what the anticipated results would be. Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  4. Outline (A) Basic Hydrologic Concepts A.1 Water Resources and Global Terrestrial Ecosystems A.2 Hydrologic budgets and conservation A.3 Evapotranspiration as a residual: the traditional hydrologic approach (B) Transpiration B.1 Direct measurements of transpiration B.2 Indirect measurements of transpiration B.3 Sapflux instrumentation and flux measurements in N. Wisconsin (C) Water Flux Modeling C.4 Groundwater / surface water interactions C.2 Incorporating spatial variation in water fluxes C.3 Incorporating physiology C.4 Results from N. Wisconsin (D) Future Directions? Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  5. Water and Global Vegetation Precipitation (mm) 500 4500 Deserts Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  6. Outline (A) Basic Hydrologic Concepts A.1 Water Resources and Global Terrestrial Ecosystems A.2 Hydrologic budgets and conservation A.3 Evapotranspiration as a residual: the traditional hydrologic approach (B) Transpiration B.1 Direct measurements of transpiration B.2 Indirect measurements of transpiration B.3 Sapflux instrumentation and flux measurements in N. Wisconsin (C) Water Flux Modeling C.4 Groundwater / surface water interactions C.2 Incorporating spatial variation in water fluxes C.3 Incorporating physiology C.4 Results from N. Wisconsin (D) Future Directions? Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  7. Hydrologic Cycle a – evaporation, non-vegetation b – evapotranspiration c – lateral transport d – precipitation e – runoff f – ground water recharge Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  8. Streamflow Discharge Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  9. Groundwater Flow Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  10. Sand and Gravel Aquifer Price County Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  11. Outline (A) Basic Hydrologic Concepts A.1 Water Resources and Global Terrestrial Ecosystems A.2 Hydrologic budgets and conservation A.3 Evapotranspiration as a residual: the traditional hydrologic approach (B) Transpiration B.1 Direct measurements of transpiration B.2 Indirect measurements of transpiration B.3 Sapflux instrumentation and flux measurements in N. Wisconsin (C) Water Flux Modeling C.4 Groundwater / surface water interactions C.2 Incorporating spatial variation in water fluxes C.3 Incorporating physiology C.4 Results from N. Wisconsin (D) Future Directions? Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  12. Watershed Boundary Stream Divide Stream junction Stream Orders First Evapotranspiration as a Residual P + GIN - (Q + E + GOUT) = 0 E = P - Q Assumes GIN = GOUT Nested Watershed Hillslope Second Third Watershed Outlet Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  13. Hillslope Profile (or Catena) Hillslope Hydrology Precipitation Evapotranspiration Throughfall and stemflow Infiltration Drainage Runoff Groundwater flow Streamflow Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  14. Outline (A) Basic Hydrologic Concepts A.1 Water Resources and Global Terrestrial Ecosystems A.2 Hydrologic budgets and conservation A.3 Evapotranspiration as a residual: the traditional hydrologic approach (B) Transpiration B.1 Direct measurements of transpiration B.2 Indirect measurements of transpiration B.3 Sapflux instrumentation and flux measurements in N. Wisconsin (C) Water Flux Modeling C.4 Groundwater / surface water interactions C.2 Incorporating spatial variation in water fluxes C.3 Incorporating physiology C.4 Results from N. Wisconsin (D) Future Directions? Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  15. Direct Transpiration Measurements 1) leaf level gas exchange a) direct measurement b)interrupts ambient environment c)large number of samples needed to scale up Pearcy et al. (1989); Schulze et al. (1982) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  16. Direct Transpiration Measurements 2) tree level xylem sap flow a) large number of measurements b)does not interrupt ambient environment c)requires appropriate scaling in time and space Cermak and Kucera (1973); Granier (1987); Schulze and Fichtner (1988) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  17. Direct Transpiration Measurements 3) lysimeters a) most accurate method b)large disturbance to soil environment c)difficult to measure large trees d) difficult to field replicate van Bevel and Meyers (1962); Fritschen et al. (1973) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  18. 4) micrometeorological techniques a) direct ecosystem level measurement b)requires appropriate site conditions c)can not separate ecosystem components directly Direct Transpiration Measurements Campbell and Unsworth (1979); Kaimal (1979); Wyngaard (1981) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  19. Outline (A) Basic Hydrologic Concepts A.1 Water Resources and Global Terrestrial Ecosystems A.2 Hydrologic budgets and conservation A.3 Evapotranspiration as a residual: the traditional hydrologic approach (B) Transpiration B.1 Direct measurements of transpiration B.2 Indirect measurements of transpiration B.3 Sapflux instrumentation and flux measurements in N. Wisconsin (C) Water Flux Modeling C.4 Groundwater / surface water interactions C.2 Incorporating spatial variation in water fluxes C.3 Incorporating physiology C.4 Results from N. Wisconsin (D) Future Directions? Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  20. Indirect Evapotranspiration Estimation • Temperature-Based • Cannot resolve time intervals less than monthly • Ignore processes • Energy Balance • Simple • Relies on differences between uncertain quantities • Unreliable for large vapor pressure gradients • Mass Transfer • Uses reliable micrometeorological measurements • Data collection difficult for multiple measurement sites • Combination Methods • Combines benefits of energy balance and mass transfer • Data intensive Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  21. Thornthwaite (1949)Temperature-Based Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  22. Indirect Evapotranspiration Estimation • Temperature-Based • Cannot resolve time intervals less than monthly • Ignore processes • Energy Balance • Simple • Relies on differences between uncertain quantities • Unreliable for large vapor pressure gradients • Mass Transfer • Uses reliable micrometeorological measurements • Data collection difficult for multiple measurement sites • Combination Methods • Combines benefits of energy balance and mass transfer • Data intensive Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  23. Energy Balance Method Rn H LE G B = 0.1 (tropical oceans), 0.4 to 0.8 (temperate forests), 10.0 (deserts) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  24. Indirect Evapotranspiration Estimation • Temperature-Based • Cannot resolve time intervals less than monthly • Ignore processes • Energy Balance • Simple • Relies on differences between uncertain quantities • Unreliable for large vapor pressure gradients • Mass Transfer • Uses reliable micrometeorological measurements • Data collection difficult for multiple measurement sites • Combination Methods • Combines benefits of energy balance and mass transfer • Data intensive Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  25. Mass Transfer (Ideal Gas Law) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  26. Mass Transfer: Vertical Transport Vapor LE H Pressure Temperature Gradient Gradient Z Wind Speed LE H LE H Eddy Currents LE H M Frictional Drag LE = latent heat of evaporation M = momentum H = sensible heat Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  27. Mass Transfer: Vertical Transport Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  28. Indirect Evapotranspiration Estimation • Temperature-Based • Cannot resolve time intervals less than monthly • Ignore processes • Energy Balance • Simple • Relies on differences between uncertain quantities • Unreliable for large vapor pressure gradients • Mass Transfer • Uses reliable micrometeorological measurements • Data collection difficult for multiple measurement sites • Combination Methods • Combines benefits of energy balance and mass transfer • Data intensive Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  29. Combination Formula (Penman, 1948) Energy Vertical Transport Mass Transfer Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  30. Penman-Monteith (Monteith,1965) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  31. Priestley and Taylor (1972) • works best for low VPD; • crude for low canopy • conductance (<20mm/s) Deardorff (1978); Maufouf and Noilhan (1991) • sensitive to stability; • soil resistance not easy • to calculate; • numerous variants are • available Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  32. Outline (A) Basic Hydrologic Concepts A.1 Water Resources and Global Terrestrial Ecosystems A.2 Hydrologic budgets and conservation A.3 Evapotranspiration as a residual: the traditional hydrologic approach (B) Transpiration B.1 Direct measurements of transpiration B.2 Indirect measurements of transpiration B.3 Sapflux instrumentation and flux measurements in N. Wisconsin (C) Water Flux Modeling C.4 Groundwater / surface water interactions C.2 Incorporating spatial variation in water fluxes C.3 Incorporating physiology C.4 Results from N. Wisconsin (D) Future Directions? Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  33. Types of Tree Level Xylem Sap Flow Xylem flow velocity with heat pulses V=D/T Hard to determine true distances due to wall friction, anastomising flow paths and other problems Measurement of xylem sap mass flow (Cermak and Kucera-type sensors) 1) Null balance method maintains a constant pre-selected temperature (4 C) between temperature measurement points a) power requirements minimal because power is proportional to flow b) little empiricism c) can not determine within tree flow paths 2) Constant heating method (Granier-type sensors) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  34. Granier-Type Sap Flux Measurements Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  35. Granier-Type Sap Flux Measurements Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  36. Granier-Type Sap Flux Measurements 1)Appropriate thermal protection (Ewers and Oren 2000) a) minimize thermal gradients b) do not overinsulate 2) Sapwood estimation (Waring, et al. 1982. Whitehead et al. 1984, Ewers et al. 1999, Oren et al. 1999, Schafer et al. 2000) a) use stem cores or cross sections b) computer tomography 3) Spatial scaling within trees (Phillips et al. 1996, Ewers and Oren 2000, Oren et al. 1999, Clearwater et al. 1999, Lu et al. 2000, Ewers et al. 2002, James et al. 2002) a) need to measure both circumferential and radial trends b) appropriate use of tree allometric relations 4) Environmental measurements 5) Time lags (Kostner et al. 1992, Martin et al. 1997, Phillips et al. 1997, Ewers and Oren 2000) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  37. Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  38. Granier-Type Sap Flux Measurements 1) Appropriate thermal protection (Ewers and Oren 2000) a) minimize thermal gradients b) do not overinsulate 2) Sapwood estimation (Waring, et al. 1982. Whitehead et al. 1984, Ewers et al. 1999, Oren et al. 1999, Schafer et al. 2000) a) use stem cores or cross sections b) computer tomography 3) Spatial scaling within trees (Phillips et al. 1996, Ewers and Oren 2000, Oren et al. 1999, Clearwater et al. 1999, Lu et al. 2000, Ewers et al. 2002, James et al. 2002) a) need to measure both circumferential and radial trends b) appropriate use of tree allometric relations 4) Environmental measurements 5) Time lags (Kostner et al. 1992, Martin et al. 1997, Phillips et al. 1997, Ewers and Oren 2000) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  39. Sapwood Estimation Inner extent of sapwood Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  40. Granier-Type Sap Flux Measurements 1) Appropriate thermal protection (Ewers and Oren 2000) a) minimize thermal gradients b) do not overinsulate 2) Sapwood estimation (Waring, et al. 1982. Whitehead et al. 1984, Ewers et al. 1999, Oren et al. 1999, Schafer et al. 2000) a) use stem cores or cross sections b) computer tomography 3) Spatial scaling within trees (Phillips et al. 1996, Ewers and Oren 2000, Oren et al. 1999, Clearwater et al. 1999, Lu et al. 2000, Ewers et al. 2002, James et al. 2002) a) need to measure both circumferential and radial trends b) appropriate use of tree allometric relations 4) Environmental measurements 5) Time lags (Kostner et al. 1992, Martin et al. 1997, Phillips et al. 1997, Ewers and Oren 2000) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  41. Circumferential Trends Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  42. Allometric Relations Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  43. Granier-Type Sap Flux Measurements 1) Appropriate thermal protection (Ewers and Oren 2000) a) minimize thermal gradients b) do not overinsulate 2) Sapwood estimation (Waring, et al. 1982. Whitehead et al. 1984, Ewers et al. 1999, Oren et al. 1999, Schafer et al. 2000) a) use stem cores or cross sections b) computer tomography 3) Spatial scaling within trees (Phillips et al. 1996, Ewers and Oren 2000, Oren et al. 1999, Clearwater et al. 1999, Lu et al. 2000, Ewers et al. 2002, James et al. 2002) a) need to measure both circumferential and radial trends b) appropriate use of tree allometric relations 4) Environmental measurements 5) Time lags (Kostner et al. 1992, Martin et al. 1997, Phillips et al. 1997, Ewers and Oren 2000) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  44. Canopy Environmental Measurements Environmental measurements (VPD) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  45. Granier-Type Sap Flux Measurements 1) Appropriate thermal protection (Ewers and Oren 2000) a) minimize thermal gradients b) do not overinsulate 2) Sapwood estimation (Waring, et al. 1982. Whitehead et al. 1984, Ewers et al. 1999, Oren et al. 1999, Schafer et al. 2000) a) use stem cores or cross sections b) computer tomography 3) Spatial scaling within trees (Phillips et al. 1996, Ewers and Oren 2000, Oren et al. 1999, Clearwater et al. 1999, Lu et al. 2000, Ewers et al. 2002, James et al. 2002) a) need to measure both circumferential and radial trends b) appropriate use of tree allometric relations 4) Environmental measurements 5) Time lags (Kostner et al. 1992, Martin et al. 1997, Phillips et al. 1997, Ewers and Oren 2000) Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  46. Diurnal Time Lags and Daily Fluxes Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  47. Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  48. Canopy Transpiration – N. Wisconsin Notes: All species show exponential EC rise to a maximum with respect to vapor pressure deficit; Stomatal control exhibits similar function across species; Maximum stomatal conductance varies 2-3 fold among species Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  49. Outline (A) Basic Hydrologic Concepts A.1 Water Resources and Global Terrestrial Ecosystems A.2 Hydrologic budgets and conservation A.3 Evapotranspiration as a residual: the traditional hydrologic approach (B) Transpiration B.1 Direct measurements of transpiration B.2 Indirect measurements of transpiration B.3 Sapflux instrumentation and flux measurements in N. Wisconsin (C) Water Flux Modeling C.4 Groundwater / surface water interactions C.2 Incorporating spatial variation in water fluxes C.3 Incorporating physiology C.4 Results from N. Wisconsin (D) Future Directions? Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

  50. Recall: Groundwater Flow Ecosystem Hydrology Modeling Group email: dsmackay@facstaff.wisc.edu http://ra.forest.wisc.edu/ehmg

More Related