Simulation of snow melt and soil frost depth for soil erosion modeling: Using an energy budget approach

Human-induced soil loss, as one of the most serious environmental and economical problems in the world, has been identified and studied since the early 20th century in the U.S. However, the process of soil erosion is not all the same in every climatic zone or geographical setting. In cold areas, the occurrence of snow and soil frost influences hydrology and, in turn, the mechanisms of erosion processes. For these areas, modeling the dynamics of snow and soil frost to predict runoff and erosion accurately under different management schemes is necessary for successful soil conservation planning. After the dynamics of snow and frost are reliably modeled, the simulation of hydrologic impacts, such as rapid snowmelt and high runoff rates, from these winter phenomena can be improved. Then schemes for predicting the rates and amounts of soil erosion by water can be established on a firm hydrological footing.; This dissertation examines the potential of an energy budget approach for simulating the magnitude and variations of snow and soil frost depths. This approach first quantifies energy components that are available from the surrounding environment to soil systems. After that, it is assumed that the net sum of all energy components is consumed or compensated by water phase changes, such as snow melting or soil freezing/thawing. Therefore, the second part of this approach is to estimate the timing and quantity of snowmelt and soil frost based on the net energy value. After being tested and verified, this approach was incorporated into an operational erosion prediction model, the Water Erosion Prediction Project (WEPP) of USDA-ARS, to serve as its winter hydrology subroutine. The results of this project show that this energy budget approach has promising potential to simulate winter hydrology and can be adapted to erosion prediction models. Moreover, this approach is simple but can be further developed in the future.