Acta Geographica Sinica ›› 1997, Vol. 52 ›› Issue (2): 177-183.doi: 10.11821/xb199702011

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SOIL SURFACE RESISTANCE MODELS TO EVAPORATION AND FIELD MEASUREMENTS

Yang Bangjie, Blackewll PS,Nicholson DF   

  1. 1. Research Center for EcoEnvironmental Sciences, Academia Sinica, Beijing, 100085;
    2. Western Australian Dept.of Agriculture, Geraldton WA6530
  • Received:1994-09-01 Revised:1996-11-01 Online:1997-03-15 Published:1997-03-15

Abstract: Surface resistance to soil evaporation rs plays an important role in land surface energy models. The order of aerodynamic resistance is 10 1 and the rs is 10 0 to 10 3 and even more as the surface from saturation to air dry. Evaporation model is more sensitive to rs than ra. One layer, two layer theoretical models and an experimental model of soil surface resistance to evaporation are discussed and the field measurements in Western Australia for tillage research are presented to introduce the field measurement method. The one layer’s model considers the resistance resulted from vapor diffusion from water surface to land surface through the gradually increased top dry soil layer and maybe estimted by: rs=z(t)/Dv where z(t) is the depth of evaporation surface in the soil and Dv is vapor diffusivity in dry soil. The two layer’s model adds additional resistance from vapor cross water air interface. It is difficult to model such complex processes and a simple experimental model is used for tillage research: rs=a(θsl)b where a is the diffusive resistance across water air interface and b is the fitted parameter with measured rs data. The rs field measurement method with small lysimeters and calculating methods are introduced and the application of rs to estimate evaporation from ridge and furrows for tillage research are presented in the paper. The model is also used for regional water balance modeling.

Key words: evaporation, soil surface resistance, model, measurement

CLC Number: 

  • S152