Assessment of the gravimetric method to determine isothermal soil water diffusivity

Moisture transport in porous media is a fundamental subject in soil physics and civil engineering and therefore it is necessary to understand its mechanisms and processes involved. In this paper, the isothermal moisture diffusion, is estimated with gravimetric method for loamy sand, silty loam and clay loam soils. The basis of the method is to measure the amount of water absorbed by the small soil columns with different heights as a function of time. To evaluate the accuracy of the obtained diffusivity data they were compared with those obtained from BruceKlute method. Considering calculated logarithmic RMSE between two mentioned methods, it was confirmed the gravimetric technique may be more reliable to estimate the isothermal moisture diffusivity especially in finer texture soils. Moreover, this technique is quite simple and may be carried out with minimum laboratory facilities. Moreover, the results showed that the gravimetric method somewhat underestimated moisture diffusion D(?) as compared to Bruce-Klute method, and the difference between the two methods increased with increasing at moisture content which will be discussed in the current paper