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-moi sture-field evolution. Generally, soil moisture is known to be affected by regional climate, soil properties, and land cover, etc., among which the la nd cover may be the most crucial factor determining short-term and eventual ly long-term evolution of the soil moisture fields. This change is mainly d ue to deforestation and urbanization, which also affect the local soil clim ate. 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 dynamic s described by Entekhabi and Rodriguez-Iturbe (1994). Statistical character ization of the soil moisture field, model parameter estimation, and example application are given utilizing the Washita '92 soil moisture data. Also, the Monsoon '90 data are used for implementing the temporal statistics of t he soil moisture field. The impact of land cover change is evaluated throug h a simulation study by applying various parameter sets with different seco nd-order statistics. As a result of the study, we found that (1) as the var iability of land cover increases, the soil moisture field dries up faster, (2) the variability of the soil moisture field becomes highest during rainf all, but rapidly recovers its original variability as time elapses, and (3) the diffusion effect is limited to the period of surface runoff, and is al so very small compared with that of the loss rate.