Land Cover Change and Its Impact on Soil-Moisture-Field Evolution

This study evaluates how the change of land cover has an impact on soil-moisture-field evolution. Generally, soil moisture is known to be affected by regional climate, soil properties, and land cover, etc., among which the land cover may be the most crucial factor determining short-term and eventually long-term evolution of the soil moisture fields. This change is mainly due to deforestation and urbanization, which also affect the local soil climate. In this study, the impact of land cover change on soil-moisture-field evolution is investigated by use of a simple model of soil moisture dynamics described by Entekhabi and Rodriguez-Iturbe (1994). Statistical characterization of the soil moisture field, model parameter estimation, and example application are given utilizing the Washita ʹ92 soil moisture data. Also, the Monsoon ʹ90 data are used for implementing the temporal statistics of the soil moisture field. The impact of land cover change is evaluated through a simulation study by applying various parameter sets with different second-order statistics. As a result of the study, we found that (1) as the variability of land cover increases, the soil moisture field dries up faster, (2) the variability of the soil moisture field becomes highest during rainfall, but rapidly recovers its original variability as time elapses, and (3) the diffusion effect is limited to the period of surface runoff, and is also very small compared with that of the loss rate.