Simulation of linear and non-linear soil water deficit due to tree water uptake

Simulation of water uptake model is extremely important to anticipate the moisture content changes in the soil. it is very helpful for the development of geotechnical foundation and geo-environmental problem solving. there are several water uptake models that have been developed by previous researchers. however it is difficult to plot and to analyse the model. hence,this project focuses into the development of coding for linear and non-linear water uptake models. linear model and exponential model were simulated by using visual basic. the results were verified and showed a good match with the models. the sensitivity of the linear and the exponential model was investigated,followed by the comparison between both simulated models. the results show that the total water extraction of the linear model is not affected by rooting depth,but very sensitive to potential transpiration. for the exponential model,the increment of the total water extraction is equal to the increment of potential transpiration. besides,the extinction coefficient,b produces the least affect to the total water extraction. the total water extraction of the linear model is lower than that of the exponential model. for a common potential transpiration of 0.4 cm/day,the rate of the extraction is almost zero at 60% rooting depth and deeper when b value is 0.15/cm and higher. © 2015,penerbit utm press. all rights reserved.