Abstract:
The unsaturated hydraulic functions are key input data in numerical models of vadose zone processes. The direct measurement
of soil moisture at different suction heads requires detailed analysis of soil samples with sophisticated instruments which can be
replaced with the help of pedotransfer functions (PTFs) which are empirical relationships between the soil hydraulic properties
and the more easily obtainable basic soil properties. The CalcPTF software has been used to compute the parameters of the
most commonly used models of Brooks and Corey (BC) and Van Genuchten (VG) from PTFs for determination of soil water
retention curves on seventeen sites in the commands of Benisagar and Rangawan reservoirs in Chhatarpur district (MP), India.
The parameters of sixteen PTFs have been estimated and results have been compared with observed data using root mean square
error (RMSE), coefficient of determination (R2), 𝑅
2
adj, and graphical representation.The PTF of BC model suggested by Rawls and
Brakensiek, 1985 (BC-RB), has been found to be the best-fit PTF for sites 1, 2, 5, 6, 10, 11, 14, 15, and 17, where BCmodel by Saxton et
al., 1986 (BC-SEL), can be used formodeling the soil moisture for sites 3, 4, 9, 12, and 16. Itmay be concluded that the PTF suggested
by Rawls and Brakensiek, 1985 (BC-RB), or Saxton et al., 1986 (BC-SEL), can be used for computation of soil moisture retention
curves in the region.
