Paper Information

Journal:   JOURNAL OF AGRICULTURAL SCIENCES   Fall 2003 , Volume 9 , Number 3; Page(s) 81 To 98.
 
Paper: 

ESTIMATION OF UNSTEADY EVAPORATION FROM BARE SOILS IN THE PRESENCE OF SHALLOW GROUND WATER-TABLE BASED ON CAMPBELLS SOIL WATER RELEASE CHARACTERISTICS FUNCTION

 
 
Author(s):  ZAREEI GH., LIAGHAT A.M., HOMAEI M.
 
* 
 
Abstract: 

Evaporation from bare soils plays a significant role in hydrological cycle, particularly in arid and semi-arid regions. In such areas, a large amount of the water that enters into the soil returns to the atmosphere through evaporation. Although, in the vegetated areas, depends on the irrigation method and the growing stage of the plants, over 10 to 61 percent of the total evapotranspiration belongs to evaporation alone. In these regions, there are some areas with shallow groundwater table, evaporating a considerable amount of water into the atmosphere and accumulating salts at the upper parts of the soil profile. Thus, the evaporation phenomenon not only is responsible for water loss but also is a major reason for soil Stalinization. One major difficulty for accurate estimating of evaporation in the field conditions arises from the lack of simple function with less needed input parameters. The main purpose of this study was to develop and verify an analytical solution for one-dimensional non-steady upward flow from shallow ground water table with minimum input data. Consequently, an analytical solution was developed based on the Richards" equation with the initial and boundary conditions governing evaporation process. In this solution, the amount and instant of evaporation from the soil surface can be estimated as function of water table drawdown, impermeable layer depth, and soil hydraulic functions. The solution is based on the Campbell’s parametric equation for water release curve. Nine-soil column experiments consisting of three disturbed sandy Loam, Silty Clay Loam, and Silty Clay soils were conducted to evaluate the analytical solutions. The results indicate a reasonable agreement between the data collected and the theoretical solution. As well the analytical model underestimates the evaporation and water table drawdown in a certain period. Also the solution seems to be applicable for different soil types, requiring only few accessible input parameters.

 
Keyword(s): BARE SOIL EVAPORATION, NONSTEADY EVAPORATION, ANALYTICAL SOLUTION, WATER TABLE DRAWDOWN, SOIL DRYING, NONSTEADY UPWARD FLOW, RECHARDES' EQUATION
 
References: 
  • ندارد
 
  Persian Abstract Yearly Visit 64
 
Latest on Blog
Enter SID Blog