Understanding the Resilience of Soil Moisture Regimes

Resilience of soil moisture regimes (SMRs) describes the stability of a particular SMR and its capability to withstand disturbances. This study quantifies the ecological and engineering resilience metrics for a generic stochastic dynamical system with its stationary probability distribution. Following that, the arid, semi-arid, semi-wet and wet status of SMRs are examined and the resilience metrics are quantified, with the stationary probability distribution of soil moisture dynamics derived by Rodriguez-Iturbe et al. [1999] and Laio et al. [2001a]. In the context of engineering resilience, the recovery rate performs as a convex function of expected soil moisture ― the recovery rate reaches its minimum value at intermediate soil moisture status, and it is higher for drier and wetter status. In the context of ecological resilience, threshold hydrological condition and its hysteresis provide insights on the transitions across SMRs. Specifically, the threshold infiltration conditions for the transition between arid and semi-arid SMRs are expected to be useful for controlling the desertification prevention and soil erosion. Moreover, the influences of marginal soil-drying capability, soil porosity and root zone depth on the engineering resilience indicate that appropriate choices of soil and vegetation types help to improve the resistance of SMRs to disturbance. Therefore, the quantified resilience metrics are meaningful in maintaining the SMRs suitable for agricultural planning.