srh.noaa.gov
The Hydrology
of the Humid Tropics
Wohl, E., Barros, A., Brunsell,
N., Chappell, N. A., Coe, M.,
Giambelluca, T., ... & Og...
Review Article
Various perspectives from the international
scientific community
Examines the role hydrology plays in the
f...
Tropical Hydrology – summed up
“All aspects of tropical hydrology — from fluxes of energy
and water within the atmosphere,...
1. Overview of the Humid Tropics
Between ~ 25° Latitude North and South
1/5 of global land surface
Precip>evap for >270 da...
Atmospheric components
Image sources: serc.carleton.edu;
science.nasa.gov;
iac.ethz.ch
GLOBAL
LOCAL
MICRO
Land Components
stri.si.edu
• Hydrologic forcing
• Intense convection above
rainforests
• Atmospheric latent heating
along...
Moisture Cycling (compared to mid-
latitudes
Warmer and uniform
temps
Large inter-annual and
sub-seasonal variability
More...
Río Mameyes at Puente Roto, El Yunque
Image source: Jorge Ortiz
Image source: Jorge Ortiz
• Spatial and Temporal Gradients...
Moisture Cycling (cont.)
Greater water and
terrestrial material
fluxes
rapid weathering
greater river flows
and sediment
l...
Moisture Cycling (cont.)
Water and Land Cover
Water flow and energy/carbon exchange is tied to
vegetation type, amount, age, density
wikipedia.org
(Tropical) land cover
is highly dynamic
due to rapid shifts in
patterns of land use
at multiple scales
Global
Water and La...
Water and Land Cover
Local scales
Grau et al. 2003
www.prgap.org
Water and Land Cover (cont.)
Important feedbacks from land cover to climate and water
fluxes (and vice versa) at local and...
Fluxes of energy,
water, and carbon and
the dynamical
processes that alter
these fluxes
Increases in CO2
changes in climat...
2. Anthropogenic Modifications
earnthis.net
Anthropogenic Modifications (cont.)
Population increase/pressure
homosapienssaveyourearth.blogspot.com
globalchange.umich....
Anthropogenic Modifications (cont.)
Fragmentation and effects on hydrological fluxes
Alterations of mass and energy cyclin...
Anthropogenic Modifications (cont.)
Land use/cover changes
Small-scale shifting cultivation
• Large-scale industrial
agric...
Anthropogenic Modifications (cont.)
Significant impacts on local and regional hydrology,
stream form and function
Brazil: ...
Anthropogenic Modifications: Climate Change
Direct alteration of tropical precipitation regime and other
aspects of the hy...
Climate Change (cont.)
Global hydrological processes are expected to
accelerate as temps rise and air moisture increases
V...
Anthropogenic Modifications (cont.)
Future drivers of alterations to
tropical hydrosphere
Freshwater supply
Food productio...
3. Research Vision
Urgent need to characterize the ‘accelerated’ nature of the
tropical water cycle.
Image source: Alonso ...
Three Main Research Areas
Moisture cycling
Catchment processes
Long-term data acquisition and organization
Moisture Cycling
More vigorous hydrologic cycle due to precipitation
variability
Accelerated geomorphic and ecologic respo...
Tropical Hydrological Cycle
Wohl et al. 2012
Empirical/field based studies on input to humid tropical
streams, stream form and function across diverse sites
Environmen...
Catchment Processes (cont.)
Biogeochemical cycling in tropical streams
Magnitudes and rates of different flow pathways, tr...
Long-term Data Acquisition & Organization
Lack of high-quality hydrological data
from tropics
Need integrated data collect...
Positive attributes of the article
Well-written & easy to read
Extensively researched
Multi-faceted and multiple scales
Go...
Critiques
There’s so much, --
where to begin?
Where’s Luquillo?
What about urban
hydrology?
Link with coastal
processes?
Questions/
Comments?
Aliraqi.org
Literature cited
Bonan, G.B. 2008. Forests and climate change: forcings, feedbacks, and the climate benefits of
forests. S...
Hydrology of humid tropics Discussion
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Paper discussion of Wohl et al. 2012 by Chris Nytch, CIAM 6117, UPR Rio Piedras

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Hydrology of humid tropics Discussion

  1. 1. srh.noaa.gov
  2. 2. The Hydrology of the Humid Tropics Wohl, E., Barros, A., Brunsell, N., Chappell, N. A., Coe, M., Giambelluca, T., ... & Ogden, F. (2012). The hydrology of the humid tropics. Nature Climate Change 2(9): 655-662. Outcome of workshop held in Hilo, Hawaii in 2011 warnercnr.colostate.edu
  3. 3. Review Article Various perspectives from the international scientific community Examines the role hydrology plays in the functioning of the humid tropics in the anthropocene State of knowledge Critical research needs to aid in understanding tropical hydrology in context of rapid environmental change
  4. 4. Tropical Hydrology – summed up “All aspects of tropical hydrology — from fluxes of energy and water within the atmosphere, to those within vegetation, land surface and subsurface systems, to stream outputs of water, sediment and solutes — are distinguished from other regions of the globe by substantially greater spatial and temporal variability, higher magnitudes, pronounced spatial gradients, and consequently the potential for rapid and significant change in response to anthropogenic alterations and associated water fluxes.” (Wohl et al. 2012, p. 657)
  5. 5. 1. Overview of the Humid Tropics Between ~ 25° Latitude North and South 1/5 of global land surface Precip>evap for >270 days/yr Tropical storms due to wind and moisture patterns Greatest amount of runoff High intensity of land-cover disturbance through forest cutting Hydrological cycle with processes spanning wide range of spatial and temporal scales en.wikipedia.org
  6. 6. Atmospheric components Image sources: serc.carleton.edu; science.nasa.gov; iac.ethz.ch GLOBAL LOCAL MICRO
  7. 7. Land Components stri.si.edu • Hydrologic forcing • Intense convection above rainforests • Atmospheric latent heating along mountain ranges • Mountains modulate and harvest atmospheric moisture • Supplies water via rivers to human pops (e.g., 1.4 billion in southeast Asia) news.nationalgeographic.com
  8. 8. Moisture Cycling (compared to mid- latitudes Warmer and uniform temps Large inter-annual and sub-seasonal variability More intense precipitation and spatial gradients of precipitation Photo credit: Jorge Ortiz Photo credit: Jorge Ortiz srh.noaa.gov
  9. 9. Río Mameyes at Puente Roto, El Yunque Image source: Jorge Ortiz Image source: Jorge Ortiz • Spatial and Temporal Gradients (cont.) Moisture Cycling (cont.)
  10. 10. Moisture Cycling (cont.) Greater water and terrestrial material fluxes rapid weathering greater river flows and sediment loads and nutrient transport Wohl et al. 2012
  11. 11. Moisture Cycling (cont.)
  12. 12. Water and Land Cover Water flow and energy/carbon exchange is tied to vegetation type, amount, age, density wikipedia.org
  13. 13. (Tropical) land cover is highly dynamic due to rapid shifts in patterns of land use at multiple scales Global Water and Land Cover (cont.) Foley et al. 2005
  14. 14. Water and Land Cover Local scales Grau et al. 2003 www.prgap.org
  15. 15. Water and Land Cover (cont.) Important feedbacks from land cover to climate and water fluxes (and vice versa) at local and global scales empowermagazine.com
  16. 16. Fluxes of energy, water, and carbon and the dynamical processes that alter these fluxes Increases in CO2 changes in climate patterns tropical vegetation responses hydrologic fluxes Water and Land Cover (cont.) Bonan 2008
  17. 17. 2. Anthropogenic Modifications earnthis.net
  18. 18. Anthropogenic Modifications (cont.) Population increase/pressure homosapienssaveyourearth.blogspot.com globalchange.umich.edu
  19. 19. Anthropogenic Modifications (cont.) Fragmentation and effects on hydrological fluxes Alterations of mass and energy cycling, more intense at local level and point source emissions
  20. 20. Anthropogenic Modifications (cont.) Land use/cover changes Small-scale shifting cultivation • Large-scale industrial agriculture en.wikipedia.org • Selective felling
  21. 21. Anthropogenic Modifications (cont.) Significant impacts on local and regional hydrology, stream form and function Brazil: Reduced evapotranspiration, shifts in rainfall phenology, dry season extended, increased discharge Increased sediment yield with commercial forestry, road construction and mining. Wohl et al. 2012, Figure 3: Example of how evapotranspiration rates in disturbed rainforests in the dry season are related to land-use history. Wohl et al. 2012, Figure 4: Schematic of local and regional hydrological response to deforestation.
  22. 22. Anthropogenic Modifications: Climate Change Direct alteration of tropical precipitation regime and other aspects of the hydrological cycle www.ucar.edu
  23. 23. Climate Change (cont.) Global hydrological processes are expected to accelerate as temps rise and air moisture increases Variable regional/local responses of precipitation patterns to climate change across tropics Diverse implications for geomorphic and hydrologic patterns and the associated human activities (e.g., agriculture) IPCC 2007
  24. 24. Anthropogenic Modifications (cont.) Future drivers of alterations to tropical hydrosphere Freshwater supply Food production Energy development Modifications of local land surface will propagate from deep groundwater to troposphere Impacts are variable across regions in time and space Dynamics best explained in the context of coupled human-natural systems. social and economic motivations governing land-use change environment.nationalgeographic.com wiki.resalliance.org
  25. 25. 3. Research Vision Urgent need to characterize the ‘accelerated’ nature of the tropical water cycle. Image source: Alonso Ramirez Holistic framework for observing and monitoring moisture cycling Emphasis on subsurface to troposphere interactions across strong physiographic and ecological gradients
  26. 26. Three Main Research Areas Moisture cycling Catchment processes Long-term data acquisition and organization
  27. 27. Moisture Cycling More vigorous hydrologic cycle due to precipitation variability Accelerated geomorphic and ecologic responses Difficult to project nonlinear feedbacks between atmospheric humidity and associated water fluxes Models that include groundwater dynamics Role of land- cover patterns on water fluxes and predicting influences of future change In context of warming climate Cross-scale assessment of spatial and temporal variability Emphasis on integrated measuring, modeling and quantification of water fluxes across the land- atmosphere continuum and between moisture reservoirs
  28. 28. Tropical Hydrological Cycle Wohl et al. 2012
  29. 29. Empirical/field based studies on input to humid tropical streams, stream form and function across diverse sites Environmental effect on spatial distribution of precipitation (and consequently runoff and sediment transport) How human landscape alterations affect evapotranspiration and runoff ratio in different environments Catchment Processes Bisley Watershed 1 Research tracts in the Luquillo Experimental Forest (Scatena 1989)
  30. 30. Catchment Processes (cont.) Biogeochemical cycling in tropical streams Magnitudes and rates of different flow pathways, transport and cycling of carbon and other nutrients Microbial processing rates and food web responses Chemical inputs from precipitation, at variable time scales Role of dust inputs Anthropogenic alterations Integrated study of chemical, physical, and biological processes that shape earth’s surface Role of floods and sediment loads during cyclonic events
  31. 31. Long-term Data Acquisition & Organization Lack of high-quality hydrological data from tropics Need integrated data collection from deep subsurface through troposphere Need long-term monitoring to catch low- frequency dynamics Need network of coordinated, concurrent experiments, open-platform databases Need more micro-meterological tower sites across all regions, coupled with remote sensing Satellite-based monitoring and radar imagery Synthesis of technologies in hydrological models of atmospheric/ecosystem interactions
  32. 32. Positive attributes of the article Well-written & easy to read Extensively researched Multi-faceted and multiple scales Good examples and supporting figures Focus on detailed research themes/questions Emphasis on cross-site coordination and infrastructure needs
  33. 33. Critiques There’s so much, -- where to begin? Where’s Luquillo? What about urban hydrology? Link with coastal processes?
  34. 34. Questions/ Comments? Aliraqi.org
  35. 35. Literature cited Bonan, G.B. 2008. Forests and climate change: forcings, feedbacks, and the climate benefits of forests. Science 320(5882):1444-1449. Foley, J.A., R. DeFries, G.P. Asner, C. Barford, G. Bonan, S.R. Carpenter, F.S. Chapin, M.T. Coe, G.C. Daily, H.K. Gibbs, J.H. Helkowski, T. Holloway, E.A. Howard, C.J. Kucharik, C. Monfreda, J.A. Patz, I.C. Prentice, N. Ramankutty, and P.K. Snyder. 2005. Global Consequences of Land Use. Science 309:570 - 574. Grau, H. R., T. M. Aide, J. K. Zimmerman, J. R. Thomlinson, E. Helmer, and X. Zou. 2003. The ecological consequences of socioeconomic and land-use changes in postagricultural Puerto Rico. Bioscience 53:1159–1168. IPCC, 2007: Summary for Policymakers. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Milliman, J. D., & Meade, R. H. 1983. World-wide delivery of river sediment to the oceans. The Journal of Geology: 1-21. Scatena, F. N. 1989. An introduction to the physiography and history of the Bisley Experiment Watersheds in the Luquillo Mountains of Puerto Rico. General Technical Report SO-72:1–22. U.S. Department of Agriculture, Southern Forest Experiment Station, New Orleans. Wohl, E.; Barros, A.; Brunsell, N.; Chappell, N.A.; Coe, M.; Giambelluca, T.; Goldsmith, S.; Harmon, R.; Hendrickx, J.; Juvik, J.; McDonnell, J. J.; Ogden, F.. (2012). The hydrology of the humid tropics. Nature Climate Change 2(9): 655-662.

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