Abstract
Evapotranspiration is a major component of both the energy and water balances of wetland tundra environments during the thaw season. Reliable estimates of evapotranspiration are required in the analysis of climatological and hydrological processes occurring within a wetland and in interfacing the surface climate with atmospheric processes. Where direct measurements are unavailable, models designed to accurately predict evapotranspiration for a particular wetland are used.
This paper evaluates the performance, sensitivity and limitations of three physically-based, one-dimensional models in the simulation of evaporation from a wetland sedge tundra in the Hudson Bay Lowland near Churchill, Manitoba. The surface of the study site consists of near-saturated peat soil with a sparse sedge canopy and a constantly varying coverage of standing water. Measured evaporation used the Bowen ratio energy balance approach, to which the model results were compared. The comparisons were conducted with hourly and daily simulations.
The three models are the Penman-Monteith model, the Shuttleworth-Wallace sparse canopy model and a modified Penman-Monteith model which is weighted for surface area of the evaporation sources.
Results from the study suggest that the weighted Penman-Monteith model has the highest potential for use as a predictive tool. In all three cases, the importance of accurately measuring the surface area of each evaporation source is recognized. The difficulty in determining a representative surface resistance for each source and the associated problems in modelling without it are discussed.
Similar content being viewed by others
Abbreviations
- BREB:
-
Bowen ratio energy balance
- P-M:
-
Penman-Monteith combination
- S-W:
-
Shuttleworth-Wallace combination
- W-P-M:
-
Weighted Penman-Monteith combination
- AE :
-
Available energy-all surfaces
- AE c :
-
Available energy-canopy (S-W, W-P-M)
- AE s :
-
Available energy-bare soil (S-W, W-P-M)
- AE w :
-
Available energy-open water (W-P-M)
- C p :
-
Specific heat of air
- D :
-
Vapor pressure deficit
- DAI:
-
Dead area index
- FAI:
-
Foliage area index
- LAI:
-
Leaf area index
- Q * :
-
Net radiation
- Q e :
-
Latent heat flux-total
- Q ec :
-
Latent heat flux-canopy (S-W, W-P-M)
- Q es :
-
Latent heat flux-bare soil (S-W, W-P-M)
- Q ew :
-
Latent heat flux-open water (W-P-M)
- Q g :
-
ground heat flux
- Q h :
-
Sensible heat flux
- S :
-
Proportion of area in bare soil
- W :
-
Proportion of surface in open water
- r a :
-
Aerodynamic resistance (P-M, W-P-M)
- r c :
-
Canopy resistance
- r s :
-
Generalized optimized surface resistance
- r st :
-
Stomatal resistance
- r ac :
-
Bulk boundary layer resistance (S-W)
- r as :
-
Aerodynamic resistance below mean canopy level (S-W)
- r ss :
-
Soil surface resistance (S-W, W-P-M)
- β:
-
Bowen ratio
- γ:
-
Psychrometer constant
- ϱ:
-
Air density
- Δ:
-
Slope of saturation vapour pressure vs temperature curve
References
Bailey, W. G. and Davies, J. A.: 1981a, ‘The Effect of Uncertainty in Aerodynamic Resistance on Evaporation Estimates from the Combination Model’,Boundary-Layer Meteorol. 20, 187–199.
Bailey, W. G. and Davies, J. A.: 1981b, ‘Bulk Stomatal Resistance Control on Evaporation’,Boundary-Layer Meteorol. 20, 401–415.
Beven, K.: 1979, ‘A Sensitivity Analysis of the Penman-Monteith Actual Evapotranspiration Estimates’,J. Hydrol. 44, 169–190.
Choudhyry, B. J. and Monteith, J. L.: 1986, ‘Implications of Stomatal Response to Saturation Deficit for the Heat Balance of Vegetation’,Agric. and Forest Meteorol. 36, 215–225.
Cowell, D. W.: 1982, ‘Earth Sciences of the Hudson Bay Lowland: Literature Review and Annotated Bibliography’,Working Paper No. 18, Lands Directorate, Environment Canada, Burlington, Ontario, 309 pp.
Halliwell, D. H. and Rouse, W. R.: 1987, ‘Soil Heat Flux in Permafrost: Characteristics and Accuracy of Measurement’,J. Climatol. 7, 571–584.
Jacobs, C. M. J. and de Bruin, H. A. R.: 1992, ‘The Sensitivity of Regional Transpiration to Land-Surface Characteristics: Significance of Feedback’,J. Climate 5, 683–698.
Jarvis, P. G. and Morison, J. I. L.: 1981, ‘The Control of Transpiration and Photosynthesis by the Stomata’, in Jarvis, P. G. and Mansfield, T. A. (eds.),Stomatal Physiology, Cambridge University Press, Cambridge, pp. 247–279.
Johnson, K. L.: 1987, ‘Wildflowers of Churchill and the Hudson Bay Region’, Manitoba Museum of Man and Nature, Winnipeg, 400 pp.
Kaufmann, M. R. and Fiscus, E. L.: 1985, ‘Water Transport through Plants — Internal Integration of Edaphic and Atmospheric Effects’,Acta Horticulturae 171, 83–93.
Lafleur, P. M. and Rouse, W. R.: 1990, ‘Application of an Energy Combination Model for Evaporation from Sparse Canopies’,Agric. and Forest Meteorol. 49, 135–153.
McNaughton, K. G. and Jarvis, P. G.: 1983, ‘Predicting Effects of Vegetation Changes on Transpiration and Evaporation’, in Kozlowski, T. T. (ed.),Water Deficits and Plant Growth,7, Academic Press, New York, pp. 1–47.
Monteith, J. L.: 1965, ‘Evaporation and Environment’,Symp. Soc. Exp. Biol., XIX, Cambridge University Press, London, pp. 205–234.
Mortsch, L.: 1990, ‘Eastern Canadian Boreal and Subarctic wetlands: a Resource Document’,Climatol. Studies No. 22, Atmosph. Environ. Serv., Environ. Canada, 169 pp.
(NWWG) National Wetlands Working Group of the Canada Committee on Ecological Land Classification: 1987, ‘The Canadian Wetland Classification System’,Series No. 21, Lands Conservation Branch, Canadian Wildlife Service, Environ. Canada, 18 pp.
Penman, H. L.: 1948, ‘Natural Evaporation from Open Water, Bare Soil and Grass’,Proc. Roy. Soc. London, Series A193, 120–145.
Priban, K. and Ondok, J. P.: 1980, ‘The Daily and Seasonal Course of Evapotranspiration from a Central European Sedge-Grass Marsh’,J. Ecology 68, 547–559.
Rouse, W. R.: 1984, ‘Microclimate at the Arctic Treeline: 2. Soil Microclimate of Tundra and Forest’,Water Resources Res. 20, 67–73.
Rouse, W. R., Carlson, D. W. and Weick, E. J.: 1992, ‘Impacts of Summer Warming on the Energy and Water Balance of Wetland Tundra’,Climatic Change 22, 305–326.
Riley, J. L.: 1990, ‘The Vascular Plants of the Hudson Bay Lowland and their Postglacial Origins’, Ontario Ministry of Natural Resources Parks and Recreational Areas Section, Central Region, Richmond Hill, 222 pp.
Rutter, A. J.: 1975, ‘The Hydrological Cycle in Vegetation’, in Monteith, J. L. (ed.),Vegetation and the Atmosphere, Volume 1, Principles’, Academic Press, London, pp. 111–154.
Shuttleworth, W. J. and Gurney, R. J.: 1990, ‘The Theoretical Relationship between Foliage Temperature and Canopy Resistance in Sparse Crops’,Quart. J. R. Meteorol. 116, 497–519.
Shuttleworth, W. J. and Wallace, J. S.: 1985, ‘Evaporation from Sparse Crops — an Energy Combination Theory’,Quart. J. Roy. Meteorol. Soc. 111, 839–855.
Tan, C. S. and Black, T. A.: 1976, ‘Factors Affecting the Canopy Resistance of a Douglas-Fir Forest’,Boundary-Layer Meteorol. 10, 475–488.
Waggoner, P. E.: 1975, ‘Micrometeorological Models’, in Monteith, J. L. (ed.),Vegetation and the Atmosphere, Volume 1, Principles’, Academic Press, London, pp. 205–228.
Wallace, J. S., Roberts, J. M. and Sivakumar, M. V. K.: 1990, ‘The Estimation of Transpiration from Sparse Dryland Millet using Stomatal Conductance and Vegetation Area Indices’,Agric. and Forest Meteorol. 51, 35–49.
Wilmott, C. J. and Wicks, D. E.: 1980, ‘An Empirical Method for the Spatial Interpolation of Monthly Precipitation within California’,Phys. Geogr. 1, 59–73.
Weller, G. and Holmgren, B.: 1974, ‘The Microclimates of the Arctic Tundra’,J. Appl. Meteorol. 13, 854–862.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Wessel, D.A., Rouse, W.R. Modelling evaporation from wetland tundra. Boundary-Layer Meteorol 68, 109–130 (1994). https://doi.org/10.1007/BF00712666
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00712666