Effect of Vertical and Horizontal Hydraulic Conductivity on Soil Moisture Response

The uncertainty associated with traditional ET based irrigation scheduling contributes to over or under water application. The lack of reliability in ET based irrigation scheduling is motivating researchers to develop on-site soil moisture-based irrigation scheduling. While soil moisture can be considered a direct measurement of available water in a soil column and hence the required amount of water to be applied to a field, the resource constraints always limit the number of soil moisture sensors to be installed in an agricultural field. Hence the simplification and linearization of the soil type and stratification are assumed. The gain due to soil moisture-based irrigation can be diminished due to this oversimplification. This study set up a numerical model to simulate soil type and stratification to investigate the effect of vertical and horizontal hydraulic conductivity on soil moisture response. Two types of experiments; first with vertical hydraulic conductivity only and second, with vertical and horizontal hydraulic conductivity combined with different numerical values have been conducted. The results from the first group of experiment are compared with the results from the second group of experiment to observe the effects. Model simulates local soil type and stratification conditions in the Central Valley of California. Once the model calibrated, the soil moisture obtained from the model can be used to identify the number of soil moisture sensors and the locations where the sensors are to be installed. Additionally, the model will provide with the information to optimize irrigation schedule for its frequency, amount, time of the day, and duration.