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Review of WA02 - Practical Lessons on Water Accounting

Review of WA02 - Practical Lessons on Water Accounting. Jeff Davids TU Delft | S4W | H2oTech. “You can’t manage a resource you don’t measure.” - Lord Kelvin. Water Accounting (WA).

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Review of WA02 - Practical Lessons on Water Accounting

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  1. Review of WA02 - Practical Lessons on Water Accounting Jeff Davids TU Delft | S4W | H2oTech

  2. “You can’t manage a resource you don’t measure.” - Lord Kelvin

  3. Water Accounting (WA) Source: Molden and Sakthivadivel 1999 and http://www.ruralwaterresources.com/wp-content/uploads/2013/09/Hydrological-Cycle.jpg

  4. Outline • Measuring or Estimating Fluxes and Changes in Storage • Partitioning Between WA Categories • Uncertainty in WA

  5. Outline • Measuring or Estimating Fluxes and Changes in Storage • Partitioning Between WA Categories • Uncertainty in WA

  6. Source: http://science.sciencemag.org/content/313/5790/1068.full

  7. Precipitation • Mechanisms of precipitation include: • Stratiform • Convective • Orographic Source:https://en.wikipedia.org/wiki/Precipitation

  8. Stratiform - Cold Front Source:http://apollo.lsc.vsc.edu/classes/met130/notes/chapter11/graphics/cf_xsect.jpg

  9. Stratiform - Warm Front Source:http://www.atmos.washington.edu/~hakim/101/fronts/ahrens_0818.jpg

  10. Convective Source:https://i.ytimg.com/vi/T9cKm8T_DD0/maxresdefault.jpg

  11. Orographic Source:https://i.ytimg.com/vi/T9cKm8T_DD0/maxresdefault.jpg

  12. S4W-Nepal Manual Gauges Onset Tipping Bucket DHM CoCoRaHS

  13. Radar (Doppler) • High energy microwave radio • Reflectivity measures intensity • Doppler shift measures velocity • Topography limits Source:weather.gov

  14. Remote Sensing • TRMM/GPM • GPM Microwave Imager (GMI) • Dual-Frequency Precipitation Radar (DPR) • Unprecedented data Source: https://www.nasa.gov/mission_pages/GPM/overview/index.html

  15. Streamflow Measurements • Water stage measurements + stage-discharge • Direct velocity measurements • Mechanical meters • Hydroacoustics • Surface radar velocimetry • Numerical modeling (e.g. rainfall - runoff) • Remote sensing

  16. Source: https://www.waterlog.com/

  17. Projects – GCID Gradient Facility and Drain Flow Measurements

  18. Evapotranspiration Measurements • Reference ET * Crop Coefficient (FAO 56) • Dependent on good land use land cover (LULC) data • Eddy Covariance • Lysimeters • DTS Bowen Ratio • Remote Sensing (e.g. SEBAL, METRIC, ETLook, etc.)

  19. FAO56 (Reference ET * Crop Coefficient) Source: www.fao.org/3/a-f2430e.pdf

  20. Lysimeters Source:https://commons.wikimedia.org/wiki/File:Lysimeter_g1.svg

  21. Vegetative index (e.g. NDVI, etc.) Sourcehttps://earthobservatory.nasa.gov/Features/MeasuringVegetation/measuring_vegetation_2.php

  22. Energy balance (e.g. SEBAL, MOD16, etc.) Source: WGM Bastiaanssen, M Menenti, RA Feddes, AAM Holtslag Journal of hydrology 212, 198-212

  23. Picture from NaarPhu and Tarai

  24. Change in Storage • Changes in groundwater storage, soil moisture, reservoirs, snow/ice, etc. • Measurements of groundwater table, reservoir levels, snow/ice depth, etc. • Measure pumping rates, recharge, etc.

  25. What Happens When Pump a Well? • Concept of Capture as formulated by Theis (1940) in his “The Source Of Water Derived From Wells.” • Well water comes from a combination of: • Change in Storage • Induced Recharge • Reduced Discharge • Capture = Sum of Induced Recharge and Reduced Discharge • Sustainable Capture: Concepts for Managing Stream Aquifer Systems (Davids and Mehl 2014) Source: Theis, 1940

  26. Groundwater - Surface Water Source: The Nature Conservancy

  27. Groundwater Storage - Storativity • “Storativity - the volume of water released from storage per unit decline in hydraulic head in the aquifer, per unit area of the aquifer.” Source:http://www.kgs.ku.edu/HighPlains/atlas/porfig.gif

  28. Groundwater Flow - Darcy’s Law • Q = K x A x dh/dl • Where: • K = Hydraulic conductivity (m/day) • A = Cross-sectional Area (m2) • dh = change in head (vertically) (m) • dl = horizonal distance (m) Source:http://blogs.egu.eu/network/geosphere/2013/09/

  29. Outline • Measuring or Estimating Fluxes and Changes in Storage • Partitioning Between WA Categories • Uncertainty in WA

  30. Partitioning Between WA Categories Process Non-Proc Beneficial Depleted Non-Ben Inflow Committed Outflow + = ΔS Non-Com Utilizable Outflow Non-Util Source: Molden and Sakthivadivel 1999

  31. Partitioning Between WA Categories Inflow (90) Depleted (60) Beneficial (40) Process (25) Gross Inflow Non-Process (15) Available Net Inflow Non-Beneficial (20) Outflow (40) Utilizable (10) • Uncommitted (20) Non-Utilizable (10) Committed (20) ΔS (10) Source: Molden and Sakthivadivel 1999

  32. Outline • Measuring or Estimating Fluxes and Changes in Storage • Partitioning Between WA Categories • Uncertainty in WA

  33. Uncertainty in Water Balances • To properly interpret Water Balances (WA), understanding uncertainty is critical! • Uncertainty in all measured/estimated fluxes propagates through to the “closure” term • Garbage In = Garbage Out • Uncertainty depends on data availability, methodology, etc.

  34. Uncertainty in Water Balances • Key Sources of Uncertainty • Measurement uncertainty (human and instrument) • Theoretical or empirical uncertainty (lack of complete understanding of processes) • Spatial uncertainty • Temporal uncertainty • Uncertainty can be random and systematic

  35. Questions and Discussion

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