Estimating soil hydraulic and thermal properties using publicly available soil information for future prediction of soil temperature and water content

Abstract

Determining the soil hydraulic and thermal properties is necessary for computations in predicting the future soil temperature and water content. However, it requires a long time, enormous effort, and considerable expense, including soil sampling from the target site, laboratory testing, and optimization processing based on field observations. This study estimated soil hydraulic and thermal properties using publicly available soil information and pedotransfer functions, and examined their usefulness. Soil information was extracted from the Japanese Soil Inventory, and several pedotransfer functions were tested. The results of soil temperature and water content computations using the estimated soil hydraulic and thermal properties were compared with the computations using soil hydraulic and thermal obtained from previous studies. The estimation approach that minimized the error between the two was selected as the optimal approach. Then, the future soil temperature and water content were computed using the soil hydraulic and thermal properties obtained by the optimal estimation approach and compared with the results of previous studies. The predictions of volumetric water content and soil temperature differed due to the estimated soil hydraulic and thermal properties, but there was no significant difference in the amount of future change from the present to the future. This indicates that estimating soil hydraulic and thermal properties using publicly available soil information and pedotransfer functions may be acceptable if the estimation is limited to evaluating future changes.